CN1701110A - Cerium-based abrasive materials and their raw materials - Google Patents

Abstract

The present invention provides a cerium-based abrasive having excellent polishing characteristics such as less occurrence of scratches and having a higher polishing rate. The cerium-based abrasive material contains at least cerium oxide (CeO) as a rare earth oxide₂) Lanthanum oxide (La)₂O₃) And neodymium oxide (Nd)₂O₃) And fluorine (F) in an amount of 90 wt% or more in terms of Total Rare Earth Oxide (TREO), wherein the TREO contains cerium oxide in a weight ratio (CeO)₂the/TREO content is 50 to 65 wt%, and the weight ratio of neodymium oxide in TREO₂O₃the/TREO) is 10 to 16 weight percent. The use of the cerium-based abrasive enables a polished surface with less occurrence of polishing scratches to be obtained quickly.

Description

Cerium-based abrasive materials and their raw materials

technical field

The present invention relates to a so-called cerium-based abrasive material mainly composed of cerium oxide and its raw material.

Background technique

Briefly speaking, the cerium-based abrasive materials are produced, for example, by performing processes such as crushing, drying, sintering, crushing (crushing), and grading of ore raw materials such as bastnaesite concentrate, cerium lanthanum concentrate, and Chinese complex concentrate (refer to Japanese Patent Laid-Open No. 9-183966, Japanese Patent Laid-Open No. 2002-97457, and Japanese Patent Laid-Open No. 2002-224949). Among the exemplified raw materials, bastnaesite concentrate contains rare earth elements such as cerium, lanthanum, and neodymium, and fluorine elements, and is considered to be one of suitable raw materials for cerium-based abrasives.

For example, a typical bastnaesite concentrate has a weight ratio of about 68-73wt% in terms of total rare earth oxides (referred to as TREO below), about 6wt% of fluorine, and about 6wt% of fluorine, and about 20wt%, TREO contains about 50wt% of cerium oxide ( _CeO2 , etc.), about 35wt% of lanthanum oxide ( _{La2O3 ,} etc.), about 11wt% of neodymium oxide ( _{Nd2O3 ,} etc.), about 4wt% Praseodymium oxide (Pr ₆ O ₁₁ , etc.).

As an abrasive, it is required to be a material having excellent polishing properties, such as being less likely to cause polishing damage as much as possible. In addition, in order to efficiently manufacture products through the grinding process, it is desirable to shorten the time required for grinding as much as possible. Therefore, a material with a grinding speed as fast as possible (a material with a large grinding value) is sought as a cerium-based grinding material.

In recent years, cerium-based abrasives have been used in glass substrates for optical disks and magnetic disks, active matrix LCDs (Liquid Crystal Displays), color filters for LCD TVs, clocks, desktop electronic calculators, LCDs for cameras, and solar cells. Grinding of glass substrates for imaging, glass substrates for LSI photomasks, glass substrates such as optical lenses, and optical lenses. In this field, in particular, a cerium-based abrasive capable of performing surface polishing with higher precision and at a faster polishing rate has been demanded.

However, if the conventional cerium-based abrasives are used for grinding, large damage will occur due to the grinding accuracy required in the grinding of optical discs and magnetic disk glass substrates, etc. The speed drops sharply, so the grinding efficiency also drops sharply. Therefore, conventional cerium-based abrasives cannot fully meet the requirements of the above-mentioned fields.

disclosure of invention

In view of the above problems, an object of the present invention is to provide a cerium-based abrasive having excellent polishing properties such as less damage and a higher polishing rate.

The cerium-based abrasive material of the present invention 1 that solves the above-mentioned problems is a cerium-based abrasive material that contains at least cerium oxide, lanthanum oxide, and neodymium oxide as rare earth oxides, and contains fluorine. The material is characterized in that the total rare earth oxides The converted weight (TREO) is more than 90wt%, the weight ratio of cerium oxide in TREO (CeO ₂ /TREO) is 50wt% to 65wt%, and the weight ratio of neodymium oxide in TREO (Nd ₂ O ₃ /TREO) is 10wt% ~16 wt%.

When this cerium-based abrasive is used, there are few grinding damages, and a desired high-precision polished surface (surface to be polished) can be obtained. And it can prevent the grinding speed from dropping sharply after the grinding starts, and can maintain a higher grinding speed for a longer time. The reason for having such excellent polishing properties is not necessarily clear, but it is believed that the main reason is to increase the ratio of neodymium (neodymium oxide) in the abrasive. The proportion of neodymium oxide in TREO is about 5.0wt% in the conventional cerium-based abrasives. If such cerium-based abrasives are used for polishing, as mentioned above, damage will occur and the polishing rate will drop sharply.

In cerium-based abrasive materials, the amount of rare earth elements in the abrasive material is generally discussed by TREO. The abrasive material of the present invention is a material containing fluorine. Rare earth elements exist in the abrasive material in various forms such as oxides, oxyfluorides, or fluorides. If TREO is used, the rare earth elements in the abrasive material can be discussed relatively simply. Amount of class elements.

In the abrasive material of the present invention described above, TREO is at least 90 wt%, more preferably at least 92 wt%. When the proportion of each rare earth element in the grinding material is constant, the higher the proportion of TREO, the higher the proportion of cerium oxide that contributes most to grinding in the rare earth oxide, so a higher grinding speed can be ensured. In addition, the content of impurities, which is one of the causes of damage, is reduced, so that damage can be more reliably prevented.

However, the higher the weight ratio of cerium oxide in TREO (CeO ₂ /TREO), the more likely damage will occur. If the above upper limit is exceeded, unacceptable damage will easily occur in the aforementioned fields requiring high-precision polishing. On the other hand, the lower the ratio, the lower the polishing rate as described above, and if it is less than the above-mentioned lower limit, a sufficient polishing rate cannot be ensured. Considering these two aspects, the weight ratio of cerium oxide in TREO (CeO ₂ /TREO) is preferably 50wt%-60wt%.

In addition, the higher the weight ratio (Nd ₂ O ₃ /TREO) of neodymium oxide in TREO, the lower the polishing rate. If the above upper limit is exceeded, a sufficient polishing rate cannot be ensured. On the other hand, the lower the ratio of neodymium oxide, the more likely damage will occur, and if it is less than the above-mentioned lower limit, unacceptable polishing damage will easily occur in the aforementioned fields requiring high-precision polishing. Therefore, considering these two aspects, the weight ratio of neodymium oxide in TREO (Nd ₂ O ₃ /TREO) is preferably 11wt%-15wt%, more preferably 12wt%-14wt%.

In addition, in the above-mentioned cerium-based abrasive material of the present invention, the weight ratio of lanthanum oxide (La ₂ O ₃ /TREO) in terms of total rare earth oxides is preferably 22 wt % to 30 wt %. The higher the ratio of lanthanum oxide, the lower the polishing rate, and if it exceeds the above upper limit, a sufficient polishing rate cannot be ensured. It can be considered that if the proportion of lanthanum oxide increases, the increased portion will inevitably reduce the proportion of cerium oxide, thereby reducing the grinding speed. On the other hand, the lower the ratio of lanthanum oxide, the more likely damage will occur, and if it is lower than the above-mentioned lower limit, unacceptable polishing damage will easily occur in the aforementioned fields requiring high-precision polishing. Considering these two aspects, the proportion of lanthanum oxide in TREO is preferably 24wt%-28wt%.

In addition, the above-mentioned cerium-based abrasive material of the present invention contains praseodymium oxide, and the weight ratio of praseodymium oxide in TREO (Pr ₆ O ₁₁ /TREO) is preferably 2.0wt%-8.0wt%.

As mentioned above, not only cerium, but also lanthanum and even neodymium contribute to grinding in the grinding material, and the grinding state is different due to the different contents of lanthanum and neodymium. Therefore, the present invention 2, which is different from the above-mentioned present invention 1, was conceived when the relationship between the contents of lanthanum and neodymium and polishing was further investigated.

That is, the cerium-based abrasive material of the present invention 2 is a cerium-based abrasive material containing at least cerium oxide, lanthanum oxide, and neodymium oxide as rare earth oxides, and a cerium-based abrasive material containing fluorine element. The weight ratio of cerium oxide (CeO ₂ /TREO) in (TREO) is 45wt%～70wt%, and the weight ratio of lanthanum oxide (La ₂ O ₃ ) to neodymium oxide (Nd ₂ O ₃ ) in TREO (La ₂ O ₃ /Nd ₂ O ₃ ) is 1.4 to 2.8. Therefore, it is considered that the balance between the lanthanum and neodymium amounts of the abrasive having the weight ratio of lanthanum oxide and neodymium oxide in TREO within the above range is good, and as a result, the polishing characteristics are optimized.

If the weight ratio of lanthanum oxide to neodymium oxide (La ₂ O ₃ /Nd ₂ O ₃ ) in the abrasive of the present invention is too large or too small, the polishing rate will decrease and a sufficient polishing rate cannot be ensured. Therefore, the weight ratio (La ₂ O ₃ /Nd ₂ O ₃ ) is preferably 1.6 to 2.6.

Further, the total weight ratio of lanthanum oxide and neodymium oxide in TREO [(La ₂ O ₃ +Nd ₂ O ₃ )/TREO] is preferably 25wt%-50wt%. If the balance between lanthanum oxide and neodymium oxide is good, the suitable range of the total weight ratio of lanthanum oxide and neodymium oxide will be wider. The higher the ratio, the lower the polishing rate. If the above upper limit is exceeded, a sufficient polishing rate cannot be ensured, which is why this range is preferable. If the proportion of lanthanum oxide is increased, the increased portion will inevitably reduce the proportion of cerium oxide, thereby reducing the grinding speed. On the other hand, the lower the ratio, the more likely damage will occur, and if the ratio is less than the above-mentioned lower limit, unacceptable polishing damage will easily occur in the aforementioned fields requiring high-precision polishing. In consideration of these two points, the ratio [(La ₂ O ₃ +Nd ₂ O ₃ )/TREO] is more preferably 30 wt% to 45 wt%.

Based on the findings so far, the following cerium-based abrasives (Invention 3) are more preferable. That is, the material is a cerium-based abrasive material containing at least cerium oxide, lanthanum oxide, and neodymium oxide as rare earth oxides, and fluorine element, and its total rare earth oxide conversion weight (TREO) is 90 wt % or more, and oxidized in TREO The weight ratio of cerium (CeO ₂ /TREO) is 45wt% to 70wt%, the weight ratio of neodymium oxide in TREO (Nd ₂ O ₃ /TREO) is 10wt% to 16wt%, and the weight ratio of lanthanum oxide (La ₂ O ₃ ) to neodymium oxide (Nd ₂ O ₃ ) by weight (La ₂ O ₃ /Nd ₂ O ₃ ) is 1.4 to 2.8. The weight ratio of cerium oxide (CeO ₂ /TREO) in TREO of the abrasive material is more preferably 50wt% to 65wt%, and the weight ratio of lanthanum oxide in TREO (La ₂ O ₃ /TREO) is more preferably 22wt% to 30wt%, the weight ratio [(La ₂ O ₃ +Nd ₂ O ₃ )/TREO] of the sum of lanthanum oxide and neodymium oxide in TREO is more preferably 25wt%-50wt%.

In addition, discussing the problem of improving the grinding characteristics, the following results were obtained. That is, the abrasive material of each of the above-mentioned inventions is not limited to the abrasive material of any one of the inventions, and the weight ratio (F/TREO) of the fluorine element relative to the total rare earth oxide conversion weight is preferably 4.0wt% to 9.0wt%. . The higher the proportion of fluorine element, the rougher the grinding surface and the lower the grinding performance. If it exceeds the above upper limit, the grinding surface will have an unacceptable roughness in the aforementioned fields requiring high-precision grinding. If the amount of fluorine is too much, it is considered to be the result of strong chemical action. On the other hand, the lower the ratio of the fluorine element, the lower the polishing rate, and if it is less than the above-mentioned lower limit, a sufficient polishing rate cannot be ensured. It can be considered that when the fluorine element is small, the chemical action that contributes to polishing hardly occurs. When these two points are considered, the weight ratio (F/TREO) of the fluorine element to TREO is more preferably 5.0 wt % to 8.0 wt %. In addition, in the cerium-based abrasive material containing fluorine, part (or all) of the rare earth elements are present not as rare earth oxides but as oxyfluorides and fluorides. Therefore, the total rare earth oxide conversion weight (TREO) of the cerium-based abrasive containing fluorine element is the total rare earth oxide conversion weight obtained by converting all the rare earth elements as rare earth oxides. In addition, the amount of fluorine element mentioned here is the content of fluorine element in the cerium type abrasive material which is the measuring object of TREO.

In the cerium-based abrasives of each of the above inventions, the weight ratio [(U+Th)/TREO] of the total amount of uranium and thorium to the total rare earth oxide conversion weight is preferably 0.05 wt% or less. It is desirable that radioactive substances such as thorium and uranium contained in the cerium-based abrasive be as small as possible. Therefore, the weight ratio is preferably at most 0.005 wt%, more preferably at most 0.0005 wt%.

The weight ratio [(TREO+F)/abrasive weight] of the weight of the abrasive material to the total weight of the TREO and fluorine content of the abrasive material of the above inventions is preferably 95wt% to 105wt%. The higher the weight ratio, the rougher the polished surface and the lowered the polishing properties, and if the above upper limit is exceeded, the rough polished surface is formed which is not allowed in the aforementioned field. It is considered that this high weight ratio is due to the excess content of fluorine, which produces a strong chemical action and roughens the polishing surface. On the other hand, the lower the weight ratio, the more likely the abrasive damage will occur, and if it is less than the above-mentioned lower limit, the abrasive damage that is not allowed in the above-mentioned field will easily occur. The reason why the above-mentioned weight ratio is low is considered to be that many impurities are contained, and as a result, damage is easily generated. When these two points are considered, the said weight ratio is more preferably 98 wt% - 104 wt%.

The cerium-based abrasives of the above-mentioned inventions were examined by X-ray diffraction analysis, and the following results were obtained. The cerium-based abrasive materials of the above-mentioned inventions are preferably measured by the X-ray diffraction method using Cu-Kα line or Cu-Kα ₁ line as the X-ray source, in the range of 2θ (diffraction angle)=20° to 30° Among the X-ray diffraction peaks that appear, the X-ray diffraction peak intensity of rare earth oxide fluoride (LnOF), that is, the strongest X-ray diffraction peak intensity, and the X-ray diffraction peak intensity of cerium oxide (CeO ₂ ), that is, the strongest A material having an intensity ratio (LnOF/CeO ₂ ) of an X-ray diffraction peak intensity of 0.4 to 0.7.

The larger the X-ray diffraction peak intensity ratio is, the more likely the abrasive damage will occur. If the above-mentioned upper limit is exceeded, the abrasive damage that is not allowed in the aforementioned field will easily occur. On the other hand, the smaller the X-ray diffraction peak intensity ratio, the lower the polishing rate, and if it is less than the above-mentioned lower limit, a sufficient polishing rate cannot be ensured. Considering these two aspects, the X-ray diffraction peak intensity ratio is preferably 0.45 to 0.65.

The cerium-based abrasive materials of the above-mentioned inventions are preferably measured by the X-ray diffraction method using Cu-Kα line or Cu-Kα ₁ line as the X-ray source. Among the X-ray diffraction peaks that appear, at 2θ=24.2° The X-ray diffraction peak intensity of rare earth fluoride (LnF ₃ ), which appears within the range of ±0.5°, which is the strongest X-ray diffraction peak intensity, and the X-ray diffraction peak intensity of cerium oxide, which is the strongest X-ray diffraction peak A material whose strength ratio (LnF ₃ /CeO ₂ ) is 0.1 or less. Here, the rare earth fluoride (LnF ₃ ) is, for example, a fluoride obtained when a raw material contains a rare earth oxide and the raw material is fluorinated in the abrasive production stage.

Therefore, if the X-ray diffraction peak intensity ratio exceeds the above-mentioned upper limit, the conversion from the rare earth fluoride to the rare earth oxyfluoride may hardly proceed due to insufficient calcination, and the rare earth fluoride may remain. , or although the calcination is sufficient, the conversion from the rare earth fluoride to the rare earth oxyfluoride is limited, so the amount of fluorine element is excessive relative to the rare earth element, and the rare earth fluoride remains. An insufficiently roasted abrasive cannot secure a sufficient polishing rate, and thus is not preferable. On the other hand, although the calcination is sufficient, the abrasive with excess fluorine content is still unfavorable because it contains a relatively large amount of coarse particles that cause grinding damage. Abrasives containing a relatively excess amount of fluorine element, in the roasting stage of the abrasive material production, because the fluorine element makes the chemical action easy to play, so it can be considered that the coarse particles that cause grinding damage are generated due to excessive sintering of the abrasive material particles. Moreover, it can be considered that the abrasive material is relatively excessive in the amount of fluorine, so even if it is assumed that the coarse particles can be sufficiently reduced by pulverization and classification after roasting, if the abrasive is used for grinding, the grinding surface will bear the chemical action of excess fluorine. , so there is a rough grinding surface that is not allowed in the aforementioned fields that require high-precision grinding.

However, the X-ray diffraction peak of cerium oxide (CeO ₂ ) used in the calculation of the above-mentioned peak intensity ratio refers to the X-ray diffraction peak of rare earth oxides mainly composed of cerium, that is, it appears at 20=28.1°±1.0 ° X-ray diffraction peaks in the range.

The X-ray diffraction peak intensity of cerium oxide (CeO ₂ ) referred to here more specifically refers to the intensity of the diffraction X-ray diffraction peak of a cubic rare earth oxide (Ln _x O _y ) whose main component is cerium. Usually, x and _y of Ln _x O y satisfy 1.5≤y/x≤2, for example, it is confirmed as CeO ₂ , Ce _0..5 Nd _0.5 O _1.75 or Ce _0.75 Nd _0.25 O _1.875 . However, even an abrasive with a small Nd ₂ O ₃ /TREO is presumed to contain oxides of rare earth elements (such as La) other than Ce and Nd because it is confirmed to be a Ce—Nd—O compound. From the above findings, it is understood that cerium oxide (CeO ₂ ), such as CeO ₂ in TREO, has a different meaning from pure cerium oxide with respect to X-ray diffraction, and may not be pure cerium oxide.

The average particle size (D ₅₀ ) of the abrasive particles in the cerium-based abrasives of the above-mentioned inventions is preferably 0.7 μm to 1.6 μm. Here, the following values are used as the average particle diameter (D ₅₀ ). That is, in the particle size distribution of the cerium-based abrasive measured by the laser diffraction/scattering particle size distribution measurement method, the particle size of the particles whose cumulative volume from the small particle size side reaches 50 wt%. The larger the average particle diameter (D ₅₀ ), the more likely grinding damage will occur. If the above upper limit is exceeded, grinding damage that is not acceptable in the aforementioned field of high-precision polishing is likely to occur. On the other hand, as the average particle size (D ₅₀ ) becomes smaller, the polishing rate decreases, and if it is less than the above-mentioned lower limit, a sufficient polishing rate cannot be ensured. Taking these two aspects into consideration, the average particle diameter (D ₅₀ ) is more preferably 0.8 μm to 1.4 μm.

The BET method specific surface area of the cerium-based abrasives of the above inventions is preferably 2.0 m ² /g to 5.0 ^{m 2} /g. The larger the BET method specific surface area, the lower the polishing rate, and if the above-mentioned upper limit is exceeded, a sufficient polishing rate cannot be ensured. On the other hand, the smaller the BET method specific surface area is, the easier it is to cause damage, and if it is less than the above-mentioned lower limit, it is easy to cause unacceptable grinding damage in the aforementioned field requiring high-precision polishing. Considering these two aspects, the BET method specific surface area is more preferably 2.5m ² /g-4.0m ² /g.

Raw materials for cerium-based abrasives are discussed next.

In the above-mentioned abrasive material of the present invention, the weight ratio of total rare earth oxide conversion weight (TREO) is 90wt%, the proportion of cerium oxide in TREO (CeO ₂ /TREO) is 50wt% to 65wt%, and the proportion of neodymium oxide in TREO is A cerium-based abrasive (invention 1) with a ratio (Nd ₂ O ₃ /TREO) of 10 wt% to 16 wt%, whose raw material (invention 4) is a cerium-based abrasive containing at least cerium, lanthanum, and neodymium as rare earth elements Raw materials for materials, characterized in that the weight ratio of cerium oxide in TREO (CeO ₂ /TREO) is 50wt% to 65wt%, and the weight ratio of neodymium oxide in TREO (Nd ₂ O ₃ /TREO) is 10wt% -16 wt%, the weight ratio [(U+Th)/TREO] of the total amount of uranium and thorium to TREO is 0.05 wt% or less.

In the raw material of the cerium-based abrasive material, as the ratio of cerium oxide in TREO (CeO ₂ /TREO) increases, the prepared abrasive material becomes a material that is prone to damage. Unacceptable grinding damage is prone to occur in the aforementioned field of high-precision grinding. On the other hand, the lower the ratio of cerium oxide, the lower the polishing rate of the resulting abrasive, and if it is less than the above lower limit, it will be difficult to ensure a sufficient polishing rate. Therefore, considering these two aspects, the weight ratio of cerium oxide in TREO (CeO ₂ /TREO) is preferably 50wt%-60wt%. On the other hand, the higher the weight ratio of neodymium oxide, the lower the polishing rate of the resulting abrasive, and if it exceeds the above upper limit, it will be difficult to ensure a sufficient polishing rate. Conversely, the lower the ratio of neodymium oxide, the prepared abrasive material will become a material that is prone to damage. If it is less than the above-mentioned lower limit, unacceptable grinding damage will easily occur in the aforementioned fields that require high-precision grinding. Therefore, considering these two aspects, the weight ratio of neodymium oxide in TREO (Nd ₂ O ₃ /TREO) is preferably from 11 wt% to 15 wt%, more preferably from 12 wt% to 14 wt%.

It is desirable that the radioactive substances such as uranium and thorium in the cerium-based abrasive be as small as possible, which is why the weight ratio [(U+Th)/TREO] of the total weight of uranium and thorium to TREO is within the above-mentioned range. Ores such as bastnaesite concentrate, bastnaesite concentrate, and China complex concentrate (especially bastnaesite concentrate and China complex concentrate) contain more thorium, and are used as raw materials for grinding materials without removing uranium and thorium is bad. Therefore, the weight ratio [(U+Th)/TREO] is preferably not more than 0.005 wt%, more preferably not more than 0.0005 wt%.

In addition, the weight ratio of lanthanum oxide in TREO (La ₂ O ₃ /TREO) is preferably 22wt%-30wt%. More preferably, the proportion is 24wt% - 28wt% of the material. The lower the ratio of lanthanum oxide, the easier it is to increase the amount of release of fluorine during firing. If it is less than the above-mentioned lower limit, it will be too easy to release, and the amount of fluorine in the cerium-based abrasive material will be released during firing. Control becomes difficult.

In the abrasive material of the present invention described above, the weight ratio (CeO ₂ /TREO) of cerium oxide (CeO ₂ ) to the total rare earth oxide conversion weight (TREO) is 45 wt % to 70 wt %, and lanthanum oxide (La ₂ O ₃ ) to neodymium oxide (Nd ₂ O ₃ ) weight ratio (La ₂ O ₃ /Nd ₂ O ₃ ) is 1.4 to 2.8 cerium-based abrasives (invention 2), the raw material (invention 5) is as A raw material for a cerium-based abrasive material containing at least cerium, lanthanum, and neodymium as a rare earth element, wherein the raw material is characterized in that the weight ratio of cerium oxide in TREO (CeO ₂ /TREO) is 45 wt% to 70 wt%, and the ratio of lanthanum oxide and The weight ratio (La ₂ O ₃ /Nd ₂ O ₃ ) of neodymium oxide is 1.4 to 2.8.

The raw material of this cerium series grinding material, along with the raising of the weight ratio (CeO ₂ /TREO) of cerium oxide in TREO, the grinding material that makes becomes the material that easily produces damage, if exceed above-mentioned upper limit value, then in requirement Unacceptable grinding damage is prone to occur in the aforementioned field of high-precision grinding. On the other hand, the lower the ratio of cerium oxide, the lower the polishing rate of the resulting abrasive, and if it is less than the above-mentioned lower limit, it will be difficult to ensure a sufficient polishing rate. Therefore, considering these two aspects, the weight ratio of cerium oxide in TREO (CeO ₂ /TREO) is preferably 50wt%-60wt%. In addition, regardless of whether the weight ratio of lanthanum oxide to neodymium oxide (La ₂ O ₃ /Nd ₂ O ₃ ) is too large or too small, the polishing speed of the resulting abrasive decreases, and a sufficient polishing speed cannot be ensured. Therefore, the weight ratio of lanthanum oxide to neodymium oxide (La ₂ O ₃ /Nd ₂ O ₃ ) in TREO is more preferably 1.6 to 2.6.

In addition, the weight ratio [(U+Th)/TREO] of the total weight of uranium and thorium as raw materials to TREO is preferably at most 0.05 wt%, because radioactive substances such as uranium and thorium are preferably as small as possible. Ores such as bastnaesite concentrate, bastnaesite concentrate, and China complex concentrate (especially bastnaesite concentrate and China complex concentrate) contain more thorium, and are used as raw materials for grinding materials without removing uranium and thorium is bad. Therefore, it is more preferable that the weight ratio [(U+Th)/TREO] is not more than 0.005% by weight, and this value is more preferably not more than 0.0005% by weight.

In addition, the total weight ratio [(La ₂ O ₃ +Nd ₂ O ₃ )/TREO] of lanthanum oxide and neodymium oxide in TREO is preferably 25 wt % to 50 wt %. The lower the ratio, the easier it is to increase the amount of fluorine released during firing. If it is less than the above-mentioned lower limit, it will be released too easily, and the amount of fluorine in the cerium-based abrasive material will be reduced during firing. Control becomes difficult.

In the above-mentioned abrasive material of the present invention, the total rare earth oxide converted weight (TREO) is 90 wt% or more, the weight ratio of cerium oxide in TREO (CeO ₂ /TREO) is 45 wt% to 70 wt%, and the percentage of neodymium oxide in TREO is The weight ratio (Nd ₂ O ₃ /TREO) is 10wt% to 16wt%, the weight ratio of lanthanum oxide (La ₂ O ₃ ) to neodymium oxide (Nd ₂ O ₃ ) in TREO (La ₂ O ₃ /Nd ₂ O ₃ ) The cerium-based abrasive (invention 3) containing at least cerium oxide, lanthanum oxide, and neodymium oxide as rare earth oxides and containing fluorine element (invention 3) whose raw material (invention 6) contains at least Raw materials for cerium-based abrasive materials of cerium, lanthanum, and neodymium, wherein TREO is more than 90 wt%, the weight ratio of cerium oxide in TREO (CeO ₂ /TREO) is 45 wt% to 70 wt%, and the weight ratio of neodymium oxide in TREO is (Nd ₂ O ₃ /TREO) is 10wt% to 16wt%, and the weight ratio of lanthanum oxide (La ₂ O ₃ ) to neodymium oxide (Nd ₂ O ₃ ) in TREO (La ₂ O ₃ /Nd ₂ O ₃ ) is 1.4 ~2.8 raw materials. More preferably, the weight ratio of cerium oxide in TREO (CeO ₂ /TREO) of the raw material is 50wt% to 65wt%, and the weight ratio of lanthanum oxide in TREO (La ₂ O ₃ /TREO) is 22wt% to 30wt %, the proportion of the total weight of lanthanum oxide and neodymium oxide in TREO [(La ₂ O ₃ +Nd ₂ O ₃ )/TREO] is 25wt%-50wt%. In addition, based on the same reason as above, the weight ratio [(U+Th)/TREO] of the total weight of uranium and thorium to TREO of the raw material is preferably at most 0.05 wt%, more preferably at most 0.005 wt%, most preferably It is 0.0005 wt% or less.

And, the above-mentioned raw materials for cerium-based abrasive materials of the present invention are not limited to any one of the raw materials of the invention, and it is better that the weight ratio (Pr ₆ O ₁₁ /TREO) of praseodymium oxide in TREO is 2.0wt%～8.0wt% raw materials.

As mentioned above, radioactive substances such as uranium and thorium contained in raw materials, in addition to this, sometimes also contain a lot of calcium (Ca), barium (Ba), iron (Fe), phosphorus ( P) and other elements. Abrasives produced from ores (raw materials) containing so many elements contain a large amount of the above components as impurities. If a grinding material containing a large amount of such impurities is used, grinding damage will easily occur and the grinding speed will decrease. Therefore, if these impurities (especially iron) remain on the polishing surface, etc., the electrical and magnetic properties of the object to be polished may be lowered. This just means, no matter be the raw material of above-mentioned which one invention, the weight ratio [(Ca+ Ba+Fe+P)/TREO] is preferably not more than 2.0 wt%, more preferably not more than 1.0 wt%, most preferably not more than 0.5 wt%. The same is true for the raw materials, and the weight ratio [(Ca+Ba+Fe+P)/TREO] is preferably 2.0 wt% or less, more preferably 1.0 wt% or less, most preferably 0.5 wt% or less.

The production method of the raw material for cerium-based abrasives is briefly described as follows (raw material production method 1).

First, decompose bastnaesite concentrate and other concentrates by sulfuric acid decomposition method and alkali decomposition method, and then carry out precipitation and separate dissolution treatment respectively to reduce and remove impurities such as uranium, thorium, calcium, barium, iron, phosphorus, etc. A rare earth solution is obtained. Then, the composition of the rare earth component of the obtained rare earth solution is adjusted (adjustment of the rare earth composition). Then, the rare earth solution with the adjusted composition is mixed with a precipitating agent (such as ammonium bicarbonate, ammonium carbonate, sodium bicarbonate, sodium carbonate, ammonia, oxalic acid, ammonium oxalate, sodium oxalate, urea, etc.) to generate a rare earth compound ( For example, precipitates such as carbonates, basic carbonates, monohydroxycarbonates, hydroxides, oxalates, etc.) are filtered and washed with water to obtain the raw material for cerium-based abrasives of the present invention.

In the production of raw materials for cerium-based abrasives, solvent extraction and addition are examples of methods for reducing and removing impurities and then adjusting the composition of the rare earth solution. Solvent extraction method is to reduce impurities other than rare earth elements to a certain extent through appropriate methods. In addition, the solvent extraction method and the addition method may be implemented in combination.

First, the solvent extraction method will be described. For example, as the ratio of neodymium in the solution before solvent extraction (Nd ₂ O ₃ /TREO) is high, and the weight ratio of lanthanum oxide to neodymium oxide in the solution (La ₂ O ₃ /Nd ₂ O ₃ ) As for the solvent extraction method used in small cases, the following two methods can be exemplified. That is, a method of extracting a part of neodymium from an aqueous solution of rare earths to an organic solvent; and after the rare earth elements are almost completely extracted into an organic solvent, the organic solvent is brought into contact with an aqueous solution for back extraction, and a part of neodymium remains in the organic solvent. In the solvent, the method of back-extracting most of the other rare earth elements into the aqueous solution. In this way, the ratio of neodymium is reduced and adjusted to a ratio suitable for the present invention. Conversely, as the ratio of neodymium in the solution before solvent extraction (Nd ₂ O ₃ /TREO) is low, and the weight ratio of lanthanum oxide to neodymium oxide in the solution (La ₂ O ₃ /Nd ₂ O ₃ ) As for the solvent extraction method used in larger cases, the following methods can be exemplified. That is, leaving a part of lanthanum and cerium in the aqueous solution, extracting the other rare earth elements into the organic solvent, and then contacting the aqueous solution for back extraction, and back extracting almost all the rare earth elements extracted in the organic solvent into the aqueous solution method in . In this way, the proportion of neodymium can be increased and adjusted to a suitable proportion for the present invention.

The solvent extraction methods described here use organic solvents that are easier to extract as heavy rare earth elements, but organic solvents that are easier to extract lighter rare earth elements may also be used. And, the extraction amount and the back extraction amount of the target substance in each extraction step and the back extraction step of the above-mentioned solvent extraction method can be appropriately carried out according to different conditions such as which raw material for the abrasive material to be manufactured is the raw material of the present invention. selected.

Next, the addition method will be described. When the ratio of neodymium (Nd ₂ O ₃ /TREO) in the solution before rare earth composition adjustment is high and the weight ratio of lanthanum oxide to neodymium oxide in the solution before solvent extraction (La ₂ O ₃ /Nd ₂ O ₃ ) The addition method used when it is small is to add and mix an aqueous solution containing more lanthanum and neodymium compounds as rare earth elements [such as dissolving carbonates, hydroxides, chlorides, oxides, etc. in acids such as hydrochloric acid ( Chloride water also can) the solution that obtains after] to reduce the ratio of neodymium, and adjust to the method for the ratio that the present invention is applicable. On the contrary, when the ratio of neodymium (Nd ₂ O ₃ /TREO) in the solution before rare earth composition adjustment was low and the weight ratio of lanthanum oxide to neodymium oxide in the solution before solvent extraction (La ₂ O ₃ /Nd The addition method used when _{the 2} O ₃ ) is large is a method of adding and mixing an aqueous solution containing a compound containing a large amount of neodymium as a rare earth element to increase the ratio of neodymium and adjust it to a ratio suitable for the present invention.

The addition amount of the aqueous solution in the above addition method can be appropriately selected depending on different conditions such as which raw material for abrasives to be produced is the raw material of the present invention.

The following method (raw material manufacturing method 2) can also be employed as a method for producing the raw material for the cerium-based abrasive.

For example, in the above-mentioned abrasive material of the present invention, if the converted weight of total rare earth oxides (TREO) is more than 90 wt%, and the weight ratio of cerium oxide in TREO (CeO ₂ /TREO) is 50 wt% to 65 wt%, In the case of a cerium-based abrasive having a weight ratio of neodymium oxide in TREO (Nd ₂ O ₃ /TREO) of 10 wt% to 16 wt% (Invention 1), first, the following materials were prepared as raw materials for the abrasive. Specifically, the content of elements such as uranium, thorium, potassium, barium, iron, and phosphorus has been sufficiently reduced, but the values of (CeO ₂ /TREO) and (Nd ₂ O ₃ /TREO) may not be within the above-mentioned appropriate ranges. materials (e.g., carbonates, hydroxycarbonates, monohydroxycarbonates, hydroxides, oxalates, oxides, etc.). Then, the above-mentioned plural kinds of materials (raw materials for abrasive materials) were mixed to adjust the content of cerium and neodymium (mixing step) to obtain the raw material for cerium-based abrasive materials of the present invention.

For example, in the above-mentioned abrasive material of the present invention, if the weight ratio (CeO ₂ /TREO) of cerium oxide (CeO ₂ ) relative to the total rare earth oxide conversion weight (TREO) is 45 wt % to 70 wt %, TREO In the case of _a cerium-based abrasive material (invention 2) in _which the weight ratio (La ₂ O ₃ /Nd 2 O 3 ) of lanthanum oxide (La ₂ O ₃ ) to neodymium oxide (Nd ₂ O ₃ ) is 1.4 to 2.8 (invention 2), first , Prepare the following materials as raw materials for grinding materials. Specifically, the content of elements such as uranium, thorium, potassium, barium, iron, and phosphorus are sufficiently reduced, but the values of (CeO ₂ /TREO) and (La ₂ O ₃ /Nd ₂ O ₃ ) may not be within the above-mentioned appropriate materials (eg, carbonates, hydroxycarbonates, monohydroxycarbonates, hydroxides, oxalates, oxides, etc.). Then, the above-mentioned plural kinds of materials (raw materials for abrasive materials) were mixed to adjust the content of cerium and neodymium (mixing step) to obtain the raw material for cerium-based abrasive materials of the present invention.

The mixing step described in the production method 2 should be performed before the firing step for producing the cerium-based abrasive. That is, this mixing step is a step that can be performed at any stage in the production process of the raw material for cerium-based abrasives. For example, the above-mentioned plural kinds of raw materials (raw materials for abrasive materials) are pulverized separately, fluorinated, and then mixed. In addition, as a plurality of raw materials (raw materials for abrasive materials) to be mixed, one or more kinds of high-purity raw materials whose ratio of one kind of rare earth oxide in TREO is 99 wt % or more may be used. Although composition adjustment can be easily performed using high-purity raw materials, high-purity raw materials are expensive.

Various raw materials for abrasive materials have been described above, but the sintered product obtained by calcining the raw materials for cerium-based abrasive materials (such as calcined rare earth carbonates, basic carbonates, monohydroxy carbonates, hydroxides, etc.) , oxalate and other raw materials) and intermediates of the oxide and its raw materials) can also be used as the raw material for the cerium-based abrasive material of the present invention. The raw material for abrasives mentioned here refers to a raw material that must be subjected to a roasting step in the preparation of abrasives when it is used as a raw material to prepare abrasives. That is, the raw materials for cerium-based abrasives mentioned here include raw materials before the crushing process performed in the initial stage of abrasive production, and raw materials (intermediate raw materials) before the roasting process during the production of cerium-based abrasives. Therefore, the above-mentioned raw materials for grinding materials have been pulverized and/or fluorinated raw materials, the raw materials that have been further dried and/or pulverized, and the raw materials that have been roasted to become cerium-based grinding materials (that is, in the grinding materials The raw materials before the firing step of the production) are all the above-mentioned raw materials (intermediate raw materials) for cerium-based abrasive materials.

In addition, in the raw materials for cerium-based abrasive materials and the cerium-based abrasive materials of the above-mentioned inventions, [F/TREO], [(U+Th)/TREO], and [(Ca+Ba+Fe+P)/TREO] are relatively The weight ratio of the weight of [F], the weight of [U+Th] or the weight of [Ca+Ba+Fe+P] in terms of the weight [TREO] of the total rare earth oxides of the abrasive material and the abrasive material, and It is not the weight ratio of [F], [U+Th], [Ca+Ba+Fe+P] in [TREO]. [TREO] does not contain [F], [U+Th], [Ca+Ba+Fe+P], [F], [U+Th], [Ca+Ba+Fe+P] in [TREO] The weight ratio in is basically 0% by weight. Therefore, when calculating [F/TREO], [(U+Th)/TREO] or [(Ca+Ba+Fe+P)/TREO] of the raw materials for abrasive materials and abrasive materials, the raw materials for abrasive materials and the The weight of [TREO (total rare earth oxide conversion weight)], [F], [U+Th] and [Ca+Ba+Fe+P] of the abrasive is calculated by converting [TREO] into 100 wt%. For example, [TREO] of the grinding material is 90wt%, and when the [F] of the grinding material is 6.3wt%, the [F/TREO] of the grinding material is 6.3(wt%)÷90.0(wt%)×100(wt%) ) = 7.0 (wt%).

The best way to practice the invention

Preferred embodiments of the cerium-based abrasive of the present invention will be described below.

Embodiment 1

First, rare earth chloride (made in India) was prepared. Its composition is 46.0 wt% in terms of total rare earth oxides (hereinafter referred to as TREO), 50.3 wt% in CeO ₂ /TREO, 23.7 wt% in La ₂ O ₃ /TREO, and 20.0 wt% in Nd ₂ O ₃ /TREO %, Pr ₆ O ₁₁ /TREO is 5.2 wt%, (U+Th)/TREO is less than 0.0005 wt%, and (Ca+Ba+Fe+P)/TREO is 0.6 wt%. The rare earth chloride is sequentially crushed from cerium lanthanum concentrate (produced in India), alkaline decomposition with concentrated NaOH aqueous solution (140°C, 3 hours), hot water treatment for dissolving the phosphoric acid component in the aqueous solution, filtration, and pH Hydrochloric acid adjusted to 3.5 to 4.0 is obtained by dissolving (dissolving rare earth elements, uranium (U) and thorium (Th) remaining in the hydroxide precipitate), filtering, solvent extraction, evaporating and concentrating, and then cooling and solidifying. .

Example 1

Raw materials for cerium-based abrasives (intermediate raw materials) are produced from the prepared rare earth chlorides. First, mix and dissolve the prepared rare earth chloride and 0.1mol/L dilute hydrochloric acid to prepare a rare earth chloride solution, filter the prepared solution, and perform solvent extraction on the filtered solution. The solvent extraction uses an extractant (PC-88A: manufactured by Daihachi Chemical Industry Co., Ltd.) and a diluent (イプゾ-ル: manufactured by Idemitsu Petrochemical Co., Ltd.) that are easier to extract as the heavier rare earth elements are used. Agent) is the solvent obtained by mixing the ratio of 1/2 as an organic solvent. Then, make this organic solvent and chloride rare earth solution (TREO 210g/L) be the state of 8/1 to carry out countercurrent multistage contact (30 sections) with flow ratio (organic solvent/chlorine rare earth solution), rare earth element is extracted to in organic solvents. In this step, in the countercurrent multi-stage extraction process with the organic solvent used, in order to almost completely extract the rare earth elements in the rare earth chloride solution, a necessary amount of aqueous sodium hydroxide solution needs to be added. Then, make the organic solvent containing rare earth element and 3mol/L hydrochloric acid aqueous solution be the state of 8/1.4 to carry out counter-current multistage contact (30 sections) with flow rate ratio (organic solvent/hydrochloric acid aqueous solution), a part of praseodymium and neodymium and the ratio of neodymium Most of the rare earth elements [heavy rare earths starting from samarium (Sm) and yttrium (Y)] that are easier to extract to organic solvents remain in organic solvents, and most of lanthanum and cerium and part of praseodymium and neodymium are back-extracted to A rare earth solution (refined solution) was obtained in an aqueous hydrochloric acid solution.

After solvent extraction, mix the obtained rare earth solution and ammonium bicarbonate aqueous solution (precipitating agent) to generate the precipitation of rare earth carbonate, then filter and wash (washing) with a centrifuge to obtain the raw material for cerium-based grinding materials ( Intermediate raw materials), that is, rare earth carbonates. Its composition is 44% by weight of TREO. The weight ratio of each rare earth element in TREO was the same as that of the obtained cerium-based abrasive (see Table 1). In addition, F/TREO is less than 0.1 wt%, (U+Th)/TREO is less than 0.0005 wt%, and (Ca+Ba+Fe+P)/TREO is less than 0.4 wt%.

The above-prepared rare earth carbonate (intermediate raw material) is mixed with pure water of 2 times the weight of the raw material, and wet pulverized for 8 hours in a wet ball mill (the pulverizing medium is a zirconia ball with a diameter of 5 mm), to obtain Raw pulp. D ₅₀ of the obtained pulverized product was 0.8 μm. Then, a 10 wt% hydrofluoric acid aqueous solution was added to the obtained slurry to adjust the weight ratio (F/TREO) of the fluorine element component in the slurry, and a stirring treatment was performed for 30 minutes (hereinafter simply referred to as fluorination treatment). [F/TREO] after the fluorination treatment was 8.0 wt%. The determination of fluorine element concentration adopts the method of alkaline melting, warm water extraction and fluoride ion electrode. Then, the solid components are allowed to settle and the supernatant liquid is skimmed off, and pure water is added to carry out so-called re-slurry washing, and the washed slurry is filtered with a filter press. The obtained filter cake was dried at 140° C. for 48 hours. Next, the obtained dry cake was pulverized with a sample mill, and the obtained pulverized product was calcined (calcination temperature: 1000° C., calcining time: 12 hours). The calcined product obtained after roasting was pulverized with a sample mill, and classified with a turbo classifier (the classification point was set at 5 μm) to obtain a cerium-based abrasive material.

Example 2, 3

In these examples, the flow ratio of the organic solvent and the hydrochloric acid aqueous solution (organic Solvent/hydrochloric acid aqueous solution) is different from embodiment 1. The flow ratio (organic solvent/hydrochloric acid aqueous solution) in Example 2 was 8/1.3, and the flow ratio (organic solvent/hydrochloric acid aqueous solution) in Example 3 was 8/1.2. Conditions other than that are the same as in Example 1, and are omitted here. The TREO of the rare earth carbonate (intermediate raw material) prepared in Example 2 was 46 wt%, and the TREO of the rare earth carbonate (intermediate raw material) prepared in Example 3 was 43 wt%. The ratio by weight of each rare earth element in TREO is the same as that of the finally obtained cerium-based abrasive in any of the examples (see Table 1). Also, in any of the examples, F/TREO was less than 0.1 wt%, (U+Th)/TREO was less than 0.0005 wt%, and (Ca+Ba+Fe+P)/TREO was less than 0.4 wt%. .

Comparative example 1

Bastnaesite concentrate produced in the United States was prepared as a raw material. Its composition (weight ratio ₎ is 70wt% for TREO, 49.3wt% for _CeO2 /TREO, 34.0wt% for _La2O3 /TREO, 11.3wt% for _Nd2O3 /TREO _, and _11.3wt % for _Pr6O11 /TREO 4.0 wt%, F/TREO is 8.0 wt%, (U+Th)/TREO is 0.1 wt%, (Ca+Ba+Fe+P)/TREO is 6.8 wt%. Then, mix the prepared raw material (bastnaesite concentrate) with pure water twice the weight of the raw material, and carry out wet grinding in a wet ball mill (the grinding medium is a zirconia ball with a diameter of 5mm) for 8 hours to obtain a raw material slurry . Then, the obtained raw material slurry is sequentially subjected to the steps of repulping and washing, filtering, drying, roasting, pulverizing and classifying to obtain the cerium-based abrasive material. The conditions of each process after resizing and washing are the same as in Example 1.

Comparative example 2, 3

In these comparative examples, the conditions of the process of back-extracting rare earth elements such as lanthanum into the aqueous hydrochloric acid solution are different from those in Example 1 in that the organic solvent containing rare earth elements is contacted with 3 mol/L hydrochloric acid aqueous solution in countercurrent multistage. In comparative example 2, the flow ratio (organic solvent/hydrochloric acid aqueous solution) of organic solvent and hydrochloric acid aqueous solution is 8/1.6, almost all of the rare earth elements in the organic solvent are back-extracted in hydrochloric acid aqueous solution to obtain rare earth solution (purified solution) . The flow rate ratio (organic solvent/hydrochloric acid aqueous solution) in Comparative Example 3 was 8/1.1. Other conditions were the same as in Example 1. The TREO of the rare earth carbonate (intermediate raw material) produced in Comparative Example 2 was 42 wt%, and the TREO of the rare earth carbonate (intermediate raw material) produced in Comparative Example 3 was 46 wt%. The ratio by weight of each rare earth element in TREO was the same as that of the finally obtained cerium-based abrasive in any of the comparative examples (see Table 1). In addition, in any of the comparative examples, F/TREO was less than 0.1 wt%, (U+Th)/TREO was less than 0.0005 wt%, and (Ca+Ba+Fe+P)/TREO was less than 0.4 wt%. .

Embodiment 4～7

Except for the different conditions of the fluoridation treatment in each example, the other conditions are the same as in Example 2 to obtain cerium-based abrasive materials. [F/TREO] after fluorination treatment, embodiment 4 is 4.0wt%, embodiment 5 is 5.5wt%, embodiment 6 is 11wt%, embodiment 7 is 15wt%,

Example 8, 9

In each example, except the calcination temperature in the calcination process is different, other conditions are the same as Example 2, and cerium-based abrasive materials are obtained. Calcination temperature, embodiment 8 is 850 ℃, and embodiment 9 is 1100 ℃.

Table 1 shows the fluorine element content of the cerium-based abrasives obtained from the above-mentioned Examples and Comparative Examples, TREO, and the weight ratio of each rare earth oxide in TREO. (Ca+Ba+Fe+P)/TREO, the abrasive of Comparative Example 1 was 6.2 wt%, and the other abrasives were all less than 0.4 wt%.

Table 1 F content of grinding material (wt%) TREO of abrasive material (wt%) The weight ratio (wt%) of each rare earth oxide in TREO La ₂ O ₃ /Nd ₂ O ₃ F(wt%)+TREO(wt%) F/TREO (wt%) U+Th/TREO(wt%) _CeO2 La ₂ O ₃ Pr ₆ O ₁₁ Nd ₂ O ₃ La ₂ O ₃ +Nd ₂ O ₃ Comparative example 1 6.1 87.8 48.3 34.6 4.0 11.3 45.9 3.06 93.9 6.9 0.10 Comparative example 2 6.6 94.0 50.3 23.7 5.2 20.0 43.7 1.19 100.6 7.0 <0.0003 Example 1 6.5 93.7 53.4 25.1 5.0 15.9 41.0 1.58 100.2 6.9 <0.0003 Example 2 6.5 93.8 55.2 26.1 4.9 13.2 39.3 1.98 100.3 6.9 <0.0003 Example 3 6.4 93.7 57.7 27.0 4.7 10.5 37.5 2.57 100.1 6.8 <0.0003 Comparative example 3 6.4 93.9 59.4 28.0 4.9 7.1 35.1 3.94 100.3 6.8 <0.0003 Example 4 3.0 96.3 55.2 26.1 4.9 13.2 39.3 1.98 99.3 3.1 <0.0003 Example 5 4.4 95.4 55.2 26.1 4.9 13.2 39.3 1.98 99.8 4.6 <0.0003 Example 2 6.5 93.8 55.2 26.1 4.9 13.2 39.3 1.98 100.3 6.9 <0.0003 Example 6 8.2 92.5 55.2 26.1 4.9 13.2 39 3 1.98 100.7 8.9 <0.0003 Example 7 10.5 91.3 55.2 26.1 4.9 13.2 39.3 1.98 101.8 11.5 <0.0003 Example 8 6.7 93.7 55.2 26.1 4.9 13.2 39.3 1.98 100.4 7.2 <0.0003 Example 2 6.5 93.8 55.2 26.1 4.9 13.2 39.3 1.98 100.3 6.9 <0.0003 Example 9 6.3 93.8 55.2 26.1 4.9 13.2 39.3 1.98 100.1 6.7 <0.0003

Using the cerium-based abrasives obtained in Examples and Comparative Examples, the average particle diameter (D ₅₀ ), BET method specific surface area (BET) and diffracted X-ray intensity (Intensity) were measured. In addition, polishing tests were carried out using the cerium-based abrasives obtained in Examples and Comparative Examples to evaluate the polishing value (polishing speed), damage evaluation of the obtained polished surface, and adhesion (cleaning property). The measurement methods, polishing test methods, and evaluation methods of various polishing characteristics will be described below. The measured values and evaluation results are shown in Table 2 below.

Average particle size (D ₅₀ ) determination

The particle size distribution of the cerium-based abrasive was measured using a laser diffraction/scattering particle size distribution measuring device [manufactured by Shimadzu Corporation: SALD-2000A], and the average particle diameter (D ₅₀ : accumulated volume from the small particle diameter side) was obtained. Particle size at 50 wt%).

BET method specific surface area (BET)

According to JIS R 1626-1996 (method for measuring specific surface area by gas adsorption BET method of fine ceramic powder) [6.2 flow method (3.5)-point method], in this case, helium gas is used as carrier gas Mixed gas with nitrogen as adsorbate gas.

X-ray Diffraction Determination

The X-ray diffraction analysis of the cerium-based abrasive was performed using an X-ray diffractometer [Mack Systems Co., Ltd. product, MXP18], and the diffracted X-ray intensity was measured. In this measurement, a copper (Cu) target was used to analyze peaks appearing in a diffraction angle (2θ) range of 20° to 30° in a diffraction X-ray pattern of Cu-Kα ₁ line obtained by irradiating Cu-Kα ray. Other measurement conditions are tube voltage 40kV, tube current 150mA, measurement range 2θ=5°-80°, sampling width 0.02°, and scanning speed 4°/min. Then, based on the obtained X-ray diffraction measurement results, the X-ray diffraction peak intensity of cerium oxide (CeO ₂ ), the X-ray diffraction peak intensity of lanthanide oxyfluoride (LnOF), and the X-ray diffraction peak intensity of lanthanide fluoride (LnF ₃ ) were read. The X-ray diffraction peak intensity was obtained, and the intensity ratio (LnOF/CeO ₂ , LnF ₃ /CeO ₂ ) of each X-ray diffraction peak was obtained.

grinding test

A grinding tester [HSP-2I type, manufactured by Taito Seiki Co., Ltd.] was prepared as a grinding machine. This polishing tester is a machine that polishes the surface of the polishing object on the polishing pad while supplying the polishing material slurry to the polishing object. The polishing pad is made of polyurethane, and it is replaced with a new one every time the polishing test is performed (the polishing time is about 24 hours). Then, glass for a flat plate of 65 mmφ as a polishing object was prepared. Separately, powdery cerium-based abrasive powder and pure water were mixed to prepare 50 L of abrasive slurry having a solid content concentration of 15% by weight. The surface of the glass for a flat panel is polished with this abrasive slurry. In this grinding test, the abrasive material slurry was supplied at a rate of 5 liters/minute, and the abrasive material slurry was recycled. In addition, the pressure of the polishing pad against the polishing surface was 9.8 kPa (100 g/cm ² ), and the rotational speed of the polishing tester was set at 100 rpm.

Evaluation of grinding value (grinding speed)

30 minutes after the start of polishing, the glass for a flat plate to be polished was replaced. The replaced glass for a flat plate is glass whose weight has been measured. Grind for 10 minutes after replacing the glass for flat plate, and calculate the amount of glass weight reduction due to grinding, and obtain "grinding value 1" from this value. The grinding value of the grinding material of Comparative Example 1 was taken as a benchmark (100).

After the first 30 minutes and the subsequent 10 minutes of grinding for a total of 40 minutes, the glass for a flat plate was replaced with a new glass for a flat plate, polished for 23 hours and 20 minutes (24 hours in total), and then the glass for a flat plate to be polished was replaced. The replaced glass for a flat plate is glass whose weight has been measured. Grind for 10 minutes after replacing the glass for the flat panel, and calculate the amount of glass weight reduction due to grinding, and calculate the "grinding value 2" from this value. Here, the grinding value 2 was obtained with the grinding value 1 of the abrasive of Comparative Example 1 as a reference (100).

Calculate the "grinding value ratio (grinding value 2/grinding value 1)" based on "grinding value 1" and "grinding value 2", and evaluate cerium based on "grinding value 1", "grinding value 2" and "grinding value ratio" The grinding value (grinding speed) of the grinding material.

Evaluation of grinding damage

After polishing, the polished glass for a flat plate was washed with pure water, and the polished surface dried in a dust-free state was evaluated for damage. The damage evaluation was carried out by observing the glass surface with a reflection method using a 300,000 lux halogen lamp as a light source, scoring the number of large flaws and microscopic flaws, and performing a deduction evaluation on a scale of 100 points. This damage evaluation is based on the polishing accuracy required for fine polishing of glass substrates for hard disks or LCDs. Specifically, in Tables 2 and 5, "◎" indicates a score of 98 or more (very suitable for fine grinding of glass substrates for HD and LCD), and "○" indicates a score of less than 98 but a score of 95 or more (applicable For fine grinding of glass substrates for HD and LCD), "△" means less than 95 points but more than 90 points (can be used for fine grinding of glass substrates for HD and LCD), "×" means less than 90 points (It cannot be used for fine grinding of glass substrates for HD and LCD).

Adhesion test

Next, a test of adhesion (detergency) of abrasives was performed. In this test, firstly, the washed and dried smooth glass for optical microscope observation is immersed in the abrasive slurry, immediately taken out and temporarily dried at 50°C, and then immersed in a container filled with pure water for 5 days. Minute ultrasonic cleaning, after ultrasonic cleaning, rinse the smooth glass taken out of the container with pure water to obtain the smooth glass as the observation object. Then, the remaining amount of abrasive particles remaining on the smooth glass surface was observed with an optical microscope to evaluate the adhesion. Specifically, in Table 2 and Table 5, "○" indicates that the residue of abrasive particles is not observed and is very suitable for fine grinding, "△" indicates that a small amount of abrasive particles is observed and is suitable for fine grinding, " "×" indicates that the observed abrasive particles remain very much and are not suitable for fine grinding.

Table 2 Abrasive material properties X-ray diffraction peak intensity Grinding properties _D50 (μm) BET(m ² /g) LnOF/CeO ₂ LnF ₃ /CeO ₂ grinding value 1 grinding value 2 Grinding Value Ratio Damage assessment Adhesion evaluation Comparative example 1 1.23 3.0 0.82 <0.10 100 twenty three 0.23 △ △ Comparative example 2 1.10 3.8 0.76 <0.10 107 32 0.30 △ △ Example 1 1.13 3.5 0.62 <0.10 122 82 0.67 ○ ○ Example 2 1.18 3.3 0.55 <0.10 138 107 0.78 ◎ ○ Example 3 1.20 3.2 0.48 <0.10 132 87 0.66 ○ ○ Comparative example 3 1.22 3.0 0.33 <0.10 115 37 0.32 △ △ Example 4 0.73 4.2 0.30 <0.10 88 62 0.70 ◎ △ Example 5 0.95 3.7 0.46 <0.10 119 88 0.74 ◎ ○ Example 2 1.18 3.3 0.55 <0.10 138 107 0.78 ◎ ○ Example 6 1.29 2.8 0.63 0.10 151 110 0.73 ○ ○ Example 7 1.52 2.4 0.83 0.21 161 106 0.66 △ △ Example 8 0.91 4.0 0.47 <0.10 113 83 0.73 ◎ △ Example 2 1.18 3.3 0.55 <0.10 138 107 0.78 ◎ ○ Example 9 1.41 2.6 0.61 <0.10 154 111 0.72 ○ ○

As shown in Table 2, the grinding value (grinding value 1) of the grinding materials of Examples 1 to 3 is high immediately after the grinding starts (after 30 minutes), and also has a higher grinding value even after long-term cyclic use (grinding value 2), the decrease in grinding value due to use is relatively small (grinding value ratio = 0.66-0.78). That is, it is possible to prevent a sharp decrease in the polishing value after the polishing is started, and to maintain a higher polishing value for a longer period of time. The abrasive materials of Examples 1 to 3 also showed the advantages of being less prone to grinding damage and less likely to be adsorbed on the grinding surface. Moreover, as shown in Table 2, the abrasive materials of the examples all have excellent grinding properties, and the abrasive material of Example 2 has the best grinding properties. Correspondingly, the grinding values 2 of the abrasives of Comparative Examples 1 to 3 were remarkably low, and the grinding force dropped sharply after use (the grinding value ratio = 0.23 to 0.32). In addition, it was found that polishing damage is likely to occur, and defects such as easy adsorption on the polishing surface are found.

Therefore, discussing the data of each example and comparative example shown in Table 1, the following problems were solved.

As the cerium-based abrasive material, TREO is preferably 90 wt% or more, more preferably 92 wt% or more. The weight ratio of cerium oxide in TREO (CeO ₂ /TREO) is preferably 50 wt% or more. In addition, according to each example and comparative example 2, as a cerium-based abrasive material, the weight ratio of neodymium oxide in TREO (Nd ₂ O ₃ /TREO) is preferably 16 wt% or less. Furthermore, according to the examples and comparative example 3, as the cerium-based abrasive material, the weight ratio of neodymium oxide in TREO (Nd ₂ O ₃ /TREO) is preferably at least 10 wt%.

As the cerium-based abrasive material, the weight ratio of lanthanum oxide in TREO (La ₂ O ₃ /TREO) is preferably 30 wt% or less.

In addition, after comparing the data (Table 1) of each example and comparative example from other viewpoints, it can be seen that as a cerium-based abrasive material, the weight ratio of lanthanum oxide (La ₂ O ₃ ) to neodymium oxide (Nd ₂ O ₃ ) ( La ₂ O ₃ /Nd ₂ O ₃ ) is preferably 1.4 or more (comparison between each example and Comparative Example 2), and preferably 2.8 or less (comparison between each example and Comparative Examples 1 and 3).

Furthermore, as the cerium-based abrasive material, the total weight ratio [(La ₂ O ₃ +Nd ₂ O ₃ )/TREO] of lanthanum oxide and neodymium oxide in TREO is preferably 25 wt % to 50 wt %. In addition, comparison between Example 2 and Examples 4-7 shows that, as the cerium-based abrasive material, the weight ratio of TREO to fluorine element content (F/TREO) is preferably 4.0wt%-9.0wt%.

As the cerium-based abrasive, the weight ratio [(U+Th)/TREO] of the total weight of uranium and thorium to TREO is preferably 0.05 wt% or less. Comparing Examples 1-3 with Comparative Examples 1-3, it can be seen that the intensity ratio (LnOF/CeO ₂ ) of the above-mentioned X-ray diffraction peaks is preferably 0.4-0.7.

According to the examples, the average particle size (D ₅₀ ) of abrasive particles is preferably 0.7 μm to 1.6 μm, and the BET method specific surface area is preferably 2.0 m ² /g to 5.0 m ² /g.

As shown in Table 2, any of the abrasive materials of Example 2 and Examples 4 to 7 has a high grinding value 1, and has a relatively high grinding value 2, and the reduction of the grinding value due to use is relatively small (grinding value ratio = 0.66 to 0.78). That is, it is possible to prevent a sharp drop in the polishing value after the polishing is started, and to maintain a higher polishing value for a longer period of time. However, when comparing the abrasive material of Example 4 with Example 2, etc., it can be seen that the grinding value 1 and the grinding value 2 are slightly lower, and there is a slight adhesion. This is considered to be because the weight ratio (F/TREO) of the amount of TREO to the amount of fluorine element is smaller and the intensity ratio (LnOF/CeO ₂ ) of the X-ray diffraction peak is smaller than in Example 2 and the like. In addition, when the abrasive material of Example 7 is compared with Example 2 etc., grinding|polishing damage is a little easy to generate|occur|produce, and it has a little adhesiveness. This is considered to be because the intensity ratios (LnOF/CeO ₂ and LnF ₃ /CeO ₂ ) of the X-ray diffraction peaks were larger than in Example 2 and the like.

As shown in Table 2, the abrasive materials of Examples 2, 8 and 9 have high grinding value 1 and relatively high grinding value 2, and the decrease in grinding value due to use is relatively small (the grinding value ratio=0.72～0.78). That is, it is possible to prevent a sharp decrease in the polishing value (polishing speed) after the polishing is started, and to maintain a higher polishing value for a longer period of time. Its result shows, when using the raw material for abrasive material of the present invention to manufacture abrasive material, if calcination temperature is 800 DEG C～1200 DEG C (preferably 850 DEG C～1100 DEG C), then can make grinding value (grinding rate) Abrasive material with less reduction (larger grinding value ratio).

Embodiment 2

Next, an example and a comparative example in which cerium carbonate, lanthanum carbonate, praseodymium carbonate, and neodymium carbonate are separately calcined (roasted), mixed and prepared as raw materials, and used to manufacture cerium-based abrasives will be described.

First, prepare high-purity cerium carbonate (TREO: 45wt%, _CeO2 /TREO: 99.9wt% or more), lanthanum carbonate (TREO: 45wt%, _{La2O3 /} TREO: 99.9wt% or more), praseodymium carbonate (TREO : 45wt%, Pr ₆ O ₁₁ /TREO: 99.9wt% or more), neodymium carbonate (TREO: 45wt%, Nd ₂ O ₃ /TREO: 99.9wt% or more), were calcined (calcined) respectively. The calcination temperature is 600°C, and the calcination time is 12 hours. Cerium carbonate sinter (TREO: 83wt%, CeO ₂ /TREO: 99.9wt% or more, ignition loss: 17wt%), lanthanum carbonate sinter (TREO: 85wt%, La ₂ O ₃ /TREO: 99.9wt% or more, loss on ignition: 15wt%), sintered product of praseodymium carbonate (TREO: 86wt%, Pr ₆ O ₁₁ /TREO: more than 99.9wt%, loss on ignition: 14wt%), sintered product of neodymium carbonate ( TREO: 82 wt%, Nd ₂ O ₃ /TREO: 99.9 wt% or more, loss on ignition: 18 wt%).

The sintered products obtained above were mixed to prepare cerium-based abrasive materials (intermediate materials) used in Examples and Comparative Examples described below. Table 3 shows the composition of the cerium-based abrasive raw material (intermediate raw material) used in each example and each comparative example. In addition, the (U+Th)/TREO weight ratio of these 5 kinds of intermediate raw materials prepared by mixing was less than 0.0005 wt%, and the (Ca+Ba+Fe+P)/TREO weight ratio was less than 0.1 wt%.

table 3 The weight ratio (wt %) of each rare earth oxide in the TREO of raw material La ₂ O ₃ /Nd ₂ O _{3 CeO2} La ₂ O ₃ Pr ₆ O ₁₁ Nd ₂ O ₃ La ₂ O ₃ +Nd ₂ O ₃ Comparative example 6 55.0 32.0 5.0 8.0 40.0 4.00 Example 10 55.0 29.0 5.0 11.0 40.0 2.64 Example 11 55.0 27.0 5.0 13.0 40.0 2.08 Example 12 55.0 25.0 5.0 15.0 40.0 1.67 Comparative Example 7 55.0 22.0 5.0 18.0 40.0 1.22 Comparative Example 8 43.0 34.5 4.5 8.0 52.5 1.92 Example 13 46.0 33.0 4.0 17.0 50.0 1.94 Example 14 68.0 19.0 4.0 9.0 28.0 2.11 Comparative Example 9 72.0 16.5 3.5 8.0 24.5 2.06

Examples 10-14 and Comparative Examples 6-9

The prepared raw material for cerium-based grinding materials [intermediate raw material=rare earth carbonic acid sinter (mixture)] is mixed with pure water twice the weight of the raw material, and mixed in a wet ball mill (the grinding medium is a zirconia ball with a diameter of 5mm). Wet pulverization was performed for 8 hours to obtain a raw material slurry. D ₅₀ of the obtained pulverized product was 0.8 μm. The resulting slurry was then subjected to a fluorination treatment (the same treatment as in Example 1). [F/TREO] after the fluorination treatment was 8.0 wt%. Then, the solid components are allowed to settle and the supernatant liquid is skimmed off, and pure water is added to carry out so-called re-slurry washing, and the washed slurry is filtered with a filter press. Then, the obtained raw material slurry is dried, calcined, pulverized, and classified in order to obtain a cerium-based abrasive material. The conditions of each process after drying are the same as in Example 1.

Table 4 shows the fluorine content of the cerium-based abrasives obtained in Examples 10 to 14 and Comparative Examples 6 to 9, TREO, and the ratio by weight of each rare earth oxide in TREO. The (Ca+Ba+Fe+P)/TREO weight ratio of these abrasive materials is less than 0.1 wt%.

Table 4 F content of grinding material (wt%) TREO of abrasive material (wt%) The weight ratio (wt%) of each rare earth oxide in TREO La ₂ O ₃ /Nd ₂ O ₃ F(wt%)+TREO(wt%) F/TREO (wt%) U+Th/TREO(wt%) _CeO2 La ₂ O ₃ Pr ₆ O ₁₁ Nd ₂ O ₃ La ₂ O ₃ +Nd ₂ O ₃ Comparative example 6 6.4 94.1 55.0 32.0 5.0 8.0 40 4.00 100.5 6.8 <0.0003 Example 10 6.2 94.2 55.0 29.0 5.0 11.0 40 2.64 100.4 6.6 <0.0003 Example 11 6.5 94.3 55.0 27.0 5.0 13.0 40 2.08 100.8 6.9 <0.0003 Example 12 6.4 94.2 55.0 25.0 5.0 15.0 40 1.67 100.6 6.8 <0.0003 Comparative Example 7 6.3 94.0 55.0 22.0 5.0 18.0 40 1.22 100.3 6.7 <0.0003 Comparative Example 8 7.0 93.2 43.0 34.5 4.5 18.0 52.5 1.92 100.2 7.5 <0.0003 Example 13 6.7 93.6 46.0 33.0 4.0 17.0 50.0 1.94 100.3 7.2 <0.0003 Example 14 6.0 94.5 68.0 19.0 4.0 9.0 28.0 2.11 100.5 6.3 <0.0003 Comparative Example 9 5.7 94.5 72.0 16.5 3.5 8.0 24.5 2.06 100.2 6.0 <0.0003

The average particle diameter (D ₅₀ ), BET method specific surface area (BET) and diffracted X-ray intensity (Intensity) were measured using the cerium-based abrasives obtained in Examples and Comparative Examples. In addition, polishing tests were carried out using the cerium-based abrasives obtained in Examples and Comparative Examples to evaluate the polishing value (polishing speed), damage evaluation of the obtained polished surface, and adhesion (cleaning property). The measurement method and test method are as described above. Table 5 shows the measured values and evaluation results.

table 5 Abrasive material properties X-ray diffraction peak intensity Grinding properties _D50 (μm) BET(m ² /g) LnOF/CeO ₂ LnF ₃ /CeO ₂ grinding value 1 grinding value 2 Grinding Value Ratio Damage assessment Adhesion evaluation Comparative Example 6 1.15 3.9 0.83 <0.10 111 33 0.30 △ △ Example 10 1.19 3.6 0.65 <0.10 128 87 0.68 ○ ○ Example 11 1.24 3.5 0.53 <0.10 140 110 0.79 ◎ ○ Example 12 1.25 3.5 0.48 <0.10 131 88 0.67 ○ ○ Comparative Example 7 1.29 3.0 0.32 <0.10 116 37 0.32 △ △ Comparative Example 8 0.99 4.3 0.69 <0.10 85 26 0.31 △ x Example 13 1.04 4.0 0.59 <0.10 98 68 0.69 ◎ △ Example 14 1.33 2.5 0.49 <0.10 135 90 0.67 ○ △ Comparative Example 9 1.37 2.2 0.42 <0.10 142 92 0.65 x △

As shown in table 5, the grinding material of each embodiment has a high grinding value (grinding value 1) in the unused state, and also has a relatively high grinding value (grinding value 2) in the state after use, due to use. The reduction of the grinding value is relatively small (grinding value ratio = 0.67 ~ 0.79). The abrasive materials of the various examples also show the advantages of being less prone to grinding damage and less likely to be adsorbed on the grinding surface. Among Examples 10 to 14, the abrasive material of Example 11 had the best abrasive properties. Correspondingly, the grinding value 2 of the grinding materials of each comparative example was significantly low, and the grinding value (polishing speed) decreased sharply due to use (except for comparative example 9). In addition, it was found that polishing damage is likely to occur, and defects such as easy adsorption on the polishing surface are found.

Therefore, the data shown in Table 4 is compared with each embodiment and Comparative Examples 8-9, and it is considered that as a cerium-based abrasive material, the weight ratio (CeO ₂ /TREO) of cerium oxide in TREO is 45wt%-70wt%. good. In addition, from the comparison of each example and Comparative Examples 6 and 7, as a cerium-based abrasive material, the weight ratio of neodymium oxide in TREO (Nd ₂ O ₃ /TREO) is preferably 10wt%-16wt%. In addition, as shown in Table 5, as the cerium-based abrasive, the intensity ratio (LnOF/CeO ₂ ) of the X-ray diffraction peak is preferably 0.4 to 0.7.

In addition, after comparing the data of the examples and comparative examples shown in Table 4 from other viewpoints, it can be seen that the weight ratio of lanthanum oxide (La ₂ O ₃ ) to neodymium oxide (Nd ₂ O ₃ ) in TREO (La ₂ O ₃ /Nd ₂ O ₃ ) is preferably 1.4wt% or more from the comparison between Examples and Comparative Example 7, and preferably 2.8 or less from Example and Comparative Example 6. From Examples 13 and 14, if the weight balance of lanthanum oxide and neodymium oxide is adjusted, even if the weight ratio of neodymium oxide in TREO (Nd ₂ O ₃ /TREO) is 9wt% or 17wt%, practical grinding materials can be obtained.

Possibility of industrial use

As described above, the cerium-based abrasive of the present invention has less damage and can maintain a high polishing force for a long time. Therefore, by using the cerium-based abrasive of the present invention, a high-quality abrasive surface with less damage and less abrasive adsorption can be obtained in a shorter period of time. That is, according to the present invention, it is possible to provide a suitable cerium-based abrasive in fields requiring high-precision surface polishing performance, such as polishing of glass substrates for optical disks and magnetic disks.

Claims (11)

1. A cerium-based abrasive material, which is a cerium-based abrasive material containing at least cerium oxide, lanthanum oxide, and neodymium oxide as a rare earth oxide, and a cerium-based abrasive material containing fluorine, wherein the total rare earth oxide conversion weight (TREO) is More than 90wt%, the weight ratio of cerium oxide (CeO ₂ /TREO) in the conversion weight of total rare earth oxides is 50wt% to 65wt%, and the weight ratio of neodymium oxide in conversion weight of total rare earth oxides (Nd ₂ O ₃ /TREO) is 10wt% to 16wt%. 2 . The cerium-based abrasive material according to claim 1 , further characterized in that the weight ratio (La ₂ O ₃ /TREO) of lanthanum oxide in the converted weight of total rare earth oxides is 22wt%˜30wt%. 3. A cerium-based abrasive material, which is a cerium-based abrasive material containing at least cerium oxide, lanthanum oxide, and neodymium oxide as a rare earth oxide, and a cerium-based abrasive material containing fluorine, wherein the total rare earth oxide equivalent weight (TREO) is The weight ratio of cerium oxide (CeO ₂ /TREO) is 45wt% to 70wt%, and the weight ratio of lanthanum oxide (La ₂ O ₃ ) to neodymium oxide (Nd ₂ O ₃ ) in the conversion weight of the total rare earth oxides (La ₂ O ₃ /Nd ₂ O ₃ ) is 1.4 to 2.8. 4. The cerium-based abrasive material as claimed in claim 3, further characterized in that the total weight ratio of lanthanum oxide and neodymium oxide in the conversion weight of total rare earth oxides [(La ₂ O ₃ +Nd ₂ O ₃ ) /TREO] is 25 wt% to 50 wt%. 5. The cerium-based abrasive material according to any one of claims 1 to 4, further characterized in that, the weight ratio (F/TREO) of the fluorine element amount relative to the total rare earth oxide conversion weight is 4.0wt% ~9.0 wt%. 6. The cerium-based abrasive material according to any one of claims 1 to 5, further characterized in that the weight ratio [(U+Th) /TREO] is 0.05 wt% or less. 7. The cerium-based grinding material according to any one of claims 1 to 6, further characterized in that, by measuring with the X-ray diffraction method using Cu-K α line or Cu-K α ₁ line as X-ray source, in Among the X-ray diffraction peaks that appear in the range of 2θ (diffraction angle) = 20° to 30°, the intensity of the X-ray diffraction peak of the rare earth oxyfluoride (LnOF), that is, the strongest X-ray diffraction peak intensity, is comparable to that of cerium oxide (CeO ₂ ) The X-ray diffraction peak intensity, that is, the intensity ratio (LnOF/CeO ₂ ) of the strongest X-ray diffraction peak intensity is 0.4 to 0.7. 8. The cerium-based abrasive according to any one of claims 1-7, further characterized in that the average particle diameter (D ₅₀ ) of the abrasive particles is 0.7 μm-1.6 μm. 9. The cerium-based abrasive material according to any one of claims 1 to 8, further characterized in that the BET method specific surface area is 2.0 m ² /g to 5.0 m ² /g. 10. A raw material for a cerium-based abrasive material, which is a raw material for a cerium-based abrasive material containing at least cerium oxide, lanthanum oxide, and neodymium oxide as rare earth oxides, wherein the ratio of cerium oxide to the total rare earth oxide conversion weight is The weight ratio (CeO ₂ /TREO) is 50wt% to 65wt%, and the weight ratio of neodymium oxide in the conversion weight of the total rare earth oxides (Nd ₂ O ₃ /TREO) is 10wt% to 16wt%, relative to the total rare earth oxides The weight ratio [(U+Th)/TREO] of the total amount of uranium and thorium in terms of material conversion weight is 0.05 wt% or less. 11. A raw material for a cerium-based abrasive material, which is a raw material for a cerium-based abrasive material containing at least cerium oxide, lanthanum oxide, and neodymium oxide as rare earth oxides, wherein the proportion of cerium oxide in the total rare earth oxide conversion weight is The weight ratio (CeO ₂ /TREO) is 45wt% to 70wt%, and the weight ratio of lanthanum oxide (La ₂ O ₃ ) to neodymium oxide (Nd ₂ O ₃ ) (La ₂ O ₃ /Nd ₂ O ₃ ) is 1.4 to 2.8.