TWI711687B - Method for preparing zinc tin spinel fluorescent powder - Google Patents

Abstract

A method for preparing zinc-tin spinel fluorescent powder, comprising the following steps: step (1), preparing a precursor liquid, and the precursor liquid contains zinc salt, tin alkoxide and a solvent; step (2), adding to the precursor liquid Urea is hydrolyzed to obtain a transparent sol, wherein the molar ratio of urea to tin alkoxide is not higher than 5; step (3), subject the transparent sol to a condensation polymerization reaction to obtain a transparent gel; and (4) Dry the transparent gel, and perform annealing treatment at a temperature not lower than 700°C to obtain zinc-tin spinel phosphor powder, and the experimental formula of the zinc-tin spinel phosphor powder is Zn ₂ Sn _{1 –X} Ti _x O ₄ , 0≦x≦0.1.

Description

Method for preparing zinc tin spinel fluorescent powder

The present invention relates to a method for preparing zinc-tin spinel fluorescer powder, in particular to a method for preparing zinc-tin spinel fluoresce powder by a sol-gel method.

White light emitting diode (WLED) has the advantages of low power consumption, small size, long life, no mercury, no heat radiation, and good response speed. It has gradually replaced traditional light bulbs and has become the mainstream of lighting equipment development. .

The existing commercial WLED is a GaN blue light emitting diode (LED) coated with cerium-doped yttrium aluminum garnet (Y ₃ Al ₅ O ₁₂ : Ce) phosphor. It uses the blue light generated by the LED to excite the cerium-doped yttrium aluminum garnet phosphor powder to make the yttrium aluminum garnet phosphor powder produce yellow fluorescence, and then the blue light and the yellow phosphor are complementary mixed to produce white light, but the aforementioned commercial WLED Due to the lack of green and red light, it has the disadvantage of low color rendering. Although there is a combination of ultraviolet light or ultraviolet light chip and RGB three primary color phosphor powder to form white light with high color rendering recently, its luminous efficiency is poor, and mixing multiple phosphor powders will cause different decay rates for each phosphor powder. And produce the problem of color cast. Therefore, if a single-body phosphor powder with white light emission characteristics can be found, the aforementioned color shift problem should be improved.

Zinc-tin spinel (Zn ₂ SnO ₄ ) or zinc stannate spinel has an inverse spinel structure and a wide energy gap (~3.6 eV), and has been found to have photoluminescence properties in recent years and is suitable for application Various photoelectric or sensing devices (such as gas and humidity sensors, UV sensors, lithium battery electrode materials, dye-sensitized solar cells, etc.). Zinc-tin spinel has been found to have white light emission characteristics, which is very suitable for making white light emitting diodes. The current method for preparing zinc-tin spinel is mainly the thermal evaporation method [see Journal of Crystal Growth, vol.267 (2004), p.177-183] or the hydrothermal method [see Journal of Alloys and Compounds, vol.577(2013), p.131-137], among them, thermal evaporation or hydrothermal method is to prepare nanowires or nanoflower morphology, there is still a lack of powder materials preparation, and the radiation band is 400 ~600 nm or 350~500 nm, there is also the disadvantage of low white light color rendering.

The Republic of China Patent No. I638776 discloses a method for preparing zinc stannate spinel fluorescent powder by colloidal particle sol-gel method, which can synthesize zinc stannate spinel fluorescent powder with white light emission characteristics, and solve the aforementioned white light color rendering properties. Low problem. However, the aforementioned method requires the addition of ethylene glycol methyl ether, which belongs to the second type of toxic chemical substance, as a gelling agent, and the polycondensation reaction time (gelling time) is too long (~38 hours). In addition, the white light emission intensity of the zinc stannate spinel phosphor powder prepared by the aforementioned method has room for improvement.

Therefore, how to improve the preparation method of the existing zinc-tin spinel phosphor powder, find a method that does not need to add glycol methyl ether as a gelling agent, can reduce the polycondensation reaction time, and the obtained zinc-tin spinel phosphor powder will have better The method of high luminous intensity has become the direction of current research.

Therefore, the purpose of the present invention is to provide a method for preparing zinc-tin spinel phosphor powder. The preparation method of the zinc tin spinel fluorescent powder of the present invention does not need to add glycol methyl ether as a gelling agent, can reduce the polycondensation reaction time (ie, gel time), and the prepared zinc tin spinel fluorescent powder will have Higher luminous intensity.

Therefore, the method for preparing zinc-tin spinel phosphor powder of the present invention includes the following steps: step (1) preparing a precursor liquid, and the precursor liquid contains zinc salt, tin alkoxide and a solvent; step (2) in the precursor liquid Adding urea and performing a hydrolysis reaction to obtain a transparent sol, wherein the molar ratio of the urea to the tin alkoxide is not higher than 5; step (3) performing a condensation polymerization reaction on the transparent sol to obtain a transparent gel; And step (4) dry the transparent gel, and perform annealing treatment at a temperature not lower than 700° C. to obtain zinc-tin spinel fluorescer powder, and the experimental formula of the zinc-tin spinel fluorescer powder is Zn ₂ Sn _1–x Ti _x O ₄ , 0≦x≦0.1.

The effect of the present invention is: because the preparation method of the present invention uses the tin alkoxide as the tin source and a specific amount of urea is added as a hydrolysis aid in the process (the molar ratio of urea to tin alkoxide is not higher than 5), Therefore, the hydrolysis reaction can be promoted to greatly improve the dispersibility and homogeneity of the sol, so that the preparation method of the present invention does not need to add ethylene glycol methyl ether as a gelling agent and can promote the progress of the condensation polymerization reaction to shorten the gelation time, and the prepared The obtained zinc-tin spinel fluors powder has a lower chance of agglomeration and a smaller average particle size, which can increase the near-white light luminous intensity of the zinc-tin spinel fluors powder, and the preparation method of the present invention adds a specific amount as an activator Titanium salt can further refine the particle size of the zinc-tin spinel phosphor powder, increase its luminous intensity, and further increase the near-white color rendering of the zinc-tin spinel phosphor powder.

The content of the present invention will be described in detail below.

[step 1)]

The step (1) of the preparation method of the present invention is to prepare a precursor liquid, which contains zinc salt, tin alkoxide and solvent.

The zinc salt can be used alone or in combination of multiple types, and the zinc salt is, for example, but not limited to, zinc nitrate [Zn(NO ₃ ) ₂ ] or zinc acetate [Zn(CH ₃ COO) ₂ ]. Preferably, the zinc salt is selected from zinc nitrate, zinc acetate or a combination of the foregoing.

The tin alkoxide is, for example, but not limited to, tetramethoxytin [Sn(OCH ₃ ) ₄ ].

Preferably, the molar ratio of the zinc salt to the tin alkoxide is 2.

The solvent can be used alone or in a mixture of multiple types, and the solvent is, for example, but not limited to, an alcohol solvent. Preferably, the solvent is selected from methanol, ethanol or a combination of the foregoing.

Preferably, this step (1) is to first mix zinc salt, tin alkoxide and solvent and stir to form the precursor liquid. More preferably, this step (1) is to stir at 25-30°C. More preferably, this step (1) involves stirring for 1 to 2 hours.

[Step (2)]

Step (2) of the preparation method of the present invention is to add urea to the precursor liquid and conduct a hydrolysis reaction to obtain a transparent sol, wherein the molar ratio of urea to tin alkoxide is not higher than 5.

Preferably, the molar ratio of urea to tin alkoxide ranges from 2.5 to 3.5.

Preferably, this step (2) is to carry out the hydrolysis reaction at 25-30°C.

Preferably, the time for the hydrolysis reaction in this step (2) is 1 to 2 hours.

Preferably, this step (2) is to carry out the hydrolysis reaction in the presence of a titanium salt.

Preferably, the titanium salt is, for example, but not limited to, titanium isopropanol [Ti{OCH(CH ₃ ) ₂ } ₄ ].

Preferably, the molar ratio of the titanium salt to the tin alkoxide is in the range of 0.005 to 0.05. More preferably, the molar ratio of the titanium salt to the tin alkoxide ranges from 0.01 to 0.05. More preferably, the molar ratio of the titanium salt to the tin alkoxide is 0.03.

[Step (3)]

Step (3) of the preparation method of the present invention is to subject the transparent sol to a condensation polymerization reaction to obtain a transparent gel.

Preferably, this step (3) is to carry out the polycondensation reaction at 25-30°C.

Preferably, this step (3) is to carry out the condensation polymerization reaction at a relative humidity of 50-80%.

Preferably, this step (3) is to carry out the condensation polymerization reaction for 7-15 hours.

[Step (4)]

The step (4) of the preparation method of the present invention is to dry the transparent gel and anneal at a temperature not lower than 700° C. to obtain the zinc tin spinel phosphor powder.

Preferably, this step (4) is drying at a temperature of 100 to 150°C.

Preferably, this step (4) is annealing at a temperature greater than 800°C. More preferably, this step (4) is annealing at a temperature of 1000 to 1200°C.

Preferably, this step (4) is annealing for 2-6 hours.

Preferably, after the zinc tin spinel fluor powder is excited by excitation light with a wavelength of 328 nm, the X coordinate value of the CIE chromaticity coordinate is in the range of 0.321 to 0.382 and the Y axis coordinate value is in the range of 0.323 to 0.373. Radiate light.

The present invention will be further described with reference to the following embodiments, but it should be understood that this embodiment is only illustrative and should not be construed as a limitation of the implementation of the present invention.

Table 1 Urea concentration (U/Sn)* (mole/mole) Titanium salt addition amount** (mole/mole) Annealing temperature (℃) Annealing time (hours) Example 1 3 0 1200 2 Example 2 3 0 1000 2 Example 3 3 0 800 2 Example 4 3 0 700 2 Comparative example 1 3 0 600 2 Comparative example 2 3 0 500 2 Comparative example 3 3 0 400 2 Comparative example 4 0 0 600 2 Comparative example 5 0 0 700 2 Comparative example 6 0 0 800 2 Comparative example 7 0 0 1000 2 Comparative example 8 0 0 1200 2 Comparative example 9 0 0.01 1200 2 Comparative example 10 0 0.03 1200 2 Comparative example 11 0 0.05 1200 2 Example 5 0.5 0 1200 2 Example 6 1 0 1200 2 Example 7 5 0 1200 2 Comparative example 12 7 0 1200 2 Comparative example 13 10 0 1200 2 Example 8 3 0.03 1000 2 Example 9 1 0.01 1200 2 Example 10 1 0.03 1200 2 Example 11 1 0.05 1200 2 Example 12 3 0.005 1200 2 Example 13 3 0.01 1200 2 Example 14 3 0.02 1200 2 Example 15 3 0.03 1200 2 Example 16 3 0.04 1200 2 Example 17 3 0.05 1200 2 Example 18 3 0.07 1200 2 Example 19 3 0.1 1200 2 Example 20 3 0.03 1200 4 Example 21 3 0.03 1200 6 *: Urea concentration is the molar ratio of urea to tetramethoxytin. **: The amount of titanium salt added is the molar ratio of titanium isopropanol to tetramethoxytin.

＜ Example 1~7 , Comparative example 1~3 , Comparative example 12~13＞

The powder products of Examples 1 to 7, Comparative Examples 1 to 3 and Comparative Examples 12 to 13 are prepared according to the urea concentration (U/Sn), annealing temperature, annealing time and the following steps in Table 1 above: Step (1): Dissolve 0.4 mol of zinc nitrate and 0.2 mol of tetramethoxytin in ethanol (solvent), and stir at 25° C. for 2 hours to form a precursor solution. Step (2): After adding urea to the precursor solution and performing a hydrolysis reaction at 25° C. for 1 hour, a transparent sol is obtained. Step (3): The transparent sol is subjected to a condensation polymerization reaction at 25° C. and a relative humidity of 50% for 7 to 15 hours to obtain a transparent gel. Step (4): the transparent gel is dried at 120°C and refined into colloidal powder. Then, the colloidal powder was annealed for 2 hours and then cooled to room temperature to obtain the powder products of Examples 1 to 7, Comparative Examples 1 to 3, and Comparative Examples 12 to 13.

＜ Example 8~19＞

The preparation method of Examples 8 to 19 is similar to that of Example 1, except that the step (2) of Examples 8 to 19 is to add titanium salt to the precursor solution, then add urea, and conduct hydrolysis at 25°C After 2 hours of reaction, a transparent sol was obtained. Among them, the urea concentration (U/Sn), the addition amount of titanium salt (the molar ratio of titanium isopropanol to tetramethoxide tin), annealing temperature and annealing time of Examples 8-19 are shown in Table 1 above.

＜ Example 20~21＞

The preparation method of Examples 20-21 is similar to that of Example 15, the difference is that the annealing time of step (5) of Examples 20-21 is 4 hours (Example 20) and 6 hours (Example 21), respectively.

＜ Comparative example 4~8＞

The preparation methods of Comparative Examples 4 to 8 are similar to those of Example 1, except that step (2) of Comparative Examples 4 to 8 is that no urea is added to the precursor solution, and the hydrolysis reaction is carried out at 25°C for 1 hour. Obtain the sol. Among them, the annealing temperature and annealing time of Comparative Examples 4 to 8 are as shown in Table 1 above.

＜ Comparative example 9~11＞

The preparation method of Comparative Examples 9-11 is similar to that of Example 9, the difference is that the step (2) of Comparative Examples 9-11 is that no urea is added to the precursor solution and the hydrolysis reaction is carried out at 25°C for 2 hours. Obtain the sol. Among them, the addition amount of titanium salt (the molar ratio of titanium isopropanol to tetramethoxytin), annealing temperature and annealing time of Comparative Examples 9-11 are as shown in Table 1 above.

＜ Polycondensation reaction ( Gelatinization ) Time, appearance comparison of sol and gel ＞

Test method: prepared according to the steps (1) to (3) of the foregoing Example 1 and the various urea concentration (U/Sn) conditions listed in Table 2 below (the ratio of urea to tetramethoxytin in moles) Sol and gel. Next, observe the appearance of the sol and gel prepared under different conditions, and record the polycondensation reaction time (ie, gel time) in step (3). The results are summarized in Table 2 below.

Table 2 Urea concentration (U/Sn) (mole/mole) Gel time (hr) Sol appearance Gel appearance 0 7 Clear translucent 1 8 Clear Transparent 3 9 Clear Transparent 5 11 Clear Transparent 7 13 Clear translucent 10 15 turbid White (opaque)

Results and discussion: From the results in Table 2, it can be seen that the sol and gel obtained by adding urea and the molar ratio (U/Sn) of urea to tetramethoxytin not higher than 5 are clear and clear in appearance. Transparent. However, the sols and gels obtained without adding urea during the manufacturing process, although the appearance of the sols are all clear, the appearance of the gel is translucent. In addition, from the results in Table 2, it can be seen that although urea is added in the process but the molar ratio of urea to tetramethoxytin is higher than 5, the sol and gel obtained have a clear appearance (U/Sn=7) Or it is turbid (U/Sn=10), and its gel appearance is translucent (U/Sn=7) or white (U/Sn=10) rather than transparent. In addition, it needs to be supplemented that there is a preparation method in which urea is added and U/Sn is not higher than 5 in the process of the present invention. The addition of titanium salt has no obvious effect on the gelation time, and the appearance of the sol and gel is clear and transparent. . It can be seen from the previous paragraph that there is a preparation method in the process of the present invention where urea is added and U/Sn is not higher than 5. The appearance of the sol and gel is clear and transparent, indicating that urea can promote the dispersibility of the hydrolysis reaction (that is, it can uniformly hydrolyze ), and then a clear sol and transparent gel can be obtained later. In addition, it can be seen from the gelation time in Table 2 that compared with the Republic of China Patent No. I638781, it needs to add glycol methyl ether as a gelling agent and the polycondensation reaction time (gelling time) is ~38 In the hourly method, the present invention uses tin alkoxide, adds urea in the process and the U/Sn is not higher than 5 without additional gelling agent and can shorten the gelling time (not higher than 15 hours).

＜X- Light diffraction (X-ray diffraction, XRD) analysis ＞

Analytical method

The powder products obtained in Examples 1 to 4, 13, 15, and 17 and Comparative Examples 1 to 8 were subjected to X-ray diffraction analysis, and the obtained results are shown in Figures 1 to 3. Among them, Figure 1 is the X-ray diffraction spectra of Examples 1 to 4 and Comparative Examples 1 to 3; Figure 2 is the X-ray diffraction spectra of Comparative Examples 4 to 8; Figure 3 is Examples 1, 13, and 15 , 17 X-ray diffraction spectrum.

Results and discussion From Figure 1 and Figure 2, it can be found that regardless of whether urea is added during the preparation process, the powder products prepared at annealing temperatures below 700°C (Comparative Examples 1 to 4) are all ZnO and SnO ₂ dual phases. Crystallization, and the annealing temperature is not less than 700 ℃ (Examples 1 to 4 and Comparative Examples 5 to 8) produced powder products will have Zn ₂ SnO ₄ crystals, and when the annealing temperature is 1000 ~ 1200 ℃ ( In Examples 1 to 2 and Comparative Examples 7 to 8), the prepared powder products are mainly Zn ₂ SnO ₄ crystalline phase. According to the foregoing description, it is confirmed that the preparation method of the present invention with an annealing temperature of not less than 700 ℃ can indeed produce Zinc-tin spinel phosphor powder with Zn ₂ SnO ₄ structure is produced, and the powder product obtained by the preparation method with annealing temperature lower than 700 ℃ is ZnO/SnO ₂ powder, which is similar to the powder prepared by the present invention. The body product structure is completely different. It can also be found from Figure 1 and Figure 2 that the powder of Example 1 shows homogeneous Zn ₂ SnO ₄ crystals, while the powder of Comparative Example 8 still has a trace amount of ZnO segregated. Compared with Comparative Example 8 where urea is not added in the process, Example 1 in which urea was added in the process had better homogeneity. In addition, the results of Example 1 and Comparative Example 8 are calculated according to the Scherrer equation, and the average grain size of Zn ₂ SnO ₄ is 87.5 and 90.1 nm, respectively, which shows that compared with Comparative Example 8 where urea is not added in the process, the Example 1 with urea added has a finer grain size. It can be found from Figure 3 that when titanium salt is added during the preparation process, no matter how much the titanium salt is added (the molar ratio of titanium isopropanol to tetramethoxide tin), the second phase of titanium oxide will not be produced. , The prepared powder products are all Zn ₂ SnO ₄ crystalline phases, indicating that Ti ⁴⁺ ions in the titanium salt will replace part of the Sn ⁴⁺ ions and dissolve in the Zn ₂ SnO ₄ host lattice. In addition, compare the effects of urea concentration (U/Sn) and addition amount of titanium salt (the molar ratio of titanium isopropanol to tetramethoxytin) on the grain size of Zn ₂ SnO ₄ , and the results are summarized in Table 3 below in. According to Table 3, it can be found that when the urea concentration (U/Sn) is lower than 5, the Zn ₂ SnO ₄ grain size will be refined as the urea concentration (U/Sn) increases. When the urea concentration (U/Sn) is greater than 5, There is no significant difference; in addition, according to the results in Table 3, it can also be found that when the titanium salt addition amount (the molar ratio of titanium isopropanol to tetramethoxide tin) is 0.01 to 0.05, as the addition amount of titanium salt increases, The Zn ₂ SnO ₄ grains will be refined again, indicating that the molar ratio (U/Sn) of urea to tetramethoxytin is not higher than 5, which can promote uniform hydrolysis and thus refine the grain size. The addition of titanium salt The amount (the molar ratio of titanium isopropanol to tetramethoxytin) of 0.01-0.05 can also refine the Zn ₂ SnO ₄ grains.

table 3 Urea concentration (U/Sn) (mole/mole) Titanium salt addition amount (mole/mole) Zn ₂ SnO ₄ average grain size (nm) Annealing temperature (℃) Comparative example 8 0 0 90.1 1200 Example 5 0.5 0 89.0 1200 Example 6 1 0 88.2 1200 Example 1 3 0 87.5 1200 Example 7 5 0 87.2 1200 Comparative example 12 7 0 87.3 1200 Comparative example 13 10 0 87.5 1200 Example 13 3 0.01 86.2 1200 Example 15 3 0.03 83.5 1200 Example 17 3 0.05 82.5 1200

＜ Raman spectroscopy (Raman spectra) analysis ＞

Analytical method

The powder products obtained in Comparative Example 8, Examples 1 and 15 were analyzed by a Raman spectrometer. The Raman spectra obtained are shown in Figure 4 (Comparative Example 8), Figure 5 (Example 1) and Figure 6 (Examples). 15) Shown.

Results and discussion As can be seen from Figures 4 and 5, the powder products prepared in Example 1 and Comparative Example 8 all have the characteristic peaks of Zn ₂ SnO ₄ (528 cm ^-1 and 668 cm ^-1 ), while Comparative Example 8 The powder product still contains a characteristic peak of ZnO (376 cm ^-1 ), which shows that compared with Comparative Example 8 where urea is not added in the process, Example 1 where urea is added in the process has better homogeneity, indicating that urea is helpful For powder homogenization. It can also be found from Figures 5 and 6, that regardless of whether titanium salt is added during the preparation process, the powder products prepared in Example 1 and Example 15 all have the characteristic peaks of Zn ₂ SnO ₄ and no other segregation phases. The preparation method of the present invention does indeed prepare zinc-tin spinel fluors powder with a homogeneous Zn ₂ SnO ₄ structure, which is consistent with the result obtained by the aforementioned <X-ray diffraction analysis>.

＜ Scanning electron microscope (Scanning Electron Microscope, SEM) analysis ＞

Analytical method

The powder products obtained in Comparative Examples 7 to 8, and Examples 1 to 2, 8 and 15 were photographed with a scanning electron microscope. The SEM photographs obtained are shown in Figure 7 (Comparative Example 7) and Figure 8 (Example 2), respectively. Figure 9 (Example 8), Figure 10 (Comparative Example 8), Figure 11 (Example 1), and Figure 12 (Example 15).

Results and Discussion From Figures 7-9, it can be found that the powder products obtained in Examples 2, 8 and Comparative Example 7 are all granular. Among them, the average primary particle size of Comparative Example 7 (Figure 7) is about 31 nm. The average primary particle size of Example 2 (Figure 8) is about 26 nm, and the average primary particle size of Example 8 (Figure 9) is about 22 nm, indicating that compared to Comparative Example 7 where urea is not added in the process, Examples 2 and 8 where urea was added during the manufacturing process had a finer particle size, showing that urea helped reduce powder agglomeration and refine the particle size. In addition, Example 8 where the titanium salt was added during the manufacturing process had a finer particle size, indicating that the titanium salt helped to further refine the Zn ₂ SnO ₄ particle size. It can be seen from Figs. 10-12 that the powder products obtained in Examples 1, 15 and Comparative Example 8 are also granular. Compared with Figs. 7-9, increasing the annealing temperature will increase the particle size of the powder products. Compared with Comparative Example 8 where urea was not added in the process, Examples 1 and 15 where urea was added in the process had a smaller particle size, and Example 15 where a titanium salt was added in the process had a finer particle size It shows that urea helps to reduce the agglomeration of the powder and refine the particle size, and the addition of titanium salt in the process also helps to refine the Zn ₂ SnO ₄ particle size.

＜ Ultraviolet light - Visible light (UV-Visible Spectroscopy) Spectral analysis ＞

Analytical method

The powder products obtained in Comparative Examples 8-11, Example 1 and Examples 13, 15, and 17 were analyzed with an ultraviolet-visible light (UV-Vis) spectrometer, and the obtained absorption spectra are shown in Figure 13 (Comparative Examples 8-11 ) And Figure 14 (Examples 1, 13, 15, 17). In addition, according to the aforementioned absorption spectrum, the energy gap (Eg) of each embodiment can be calculated according to the Tauc algorithm. The obtained results are summarized in Table 4 below.

Table 4 Urea concentration (U/Sn) (mole/mole) Titanium salt addition amount (mole/mole) Energy gap (eV) Comparative example 8 0 0 3.42 Comparative example 9 0 0.01 3.44 Comparative example 10 0 0.03 3.45 Comparative example 11 0 0.05 3.48 Example 1 3 0 3.43 Example 13 3 0.01 3.46 Example 15 3 0.03 3.48 Example 17 3 0.05 3.49

Results and discussion It can be found from Figures 13-14 that, regardless of whether urea is added during the preparation process, Comparative Example 8 (Figure 13) and Example 1 (Figure 14) without addition of titanium salt all begin to have significant absorption at a wavelength of 400 nm , There is significant absorption near the wavelength of 310 nm, which is the intrinsic absorption of Zn ₂ SnO ₄ ; and Comparative Examples 9-11 (Figure 13) with addition of titanium salt and Examples 13, 15, and 17 also have obvious absorption at the wavelength of 400 nm In addition, there is no characteristic absorption of Ti ³⁺ in the wavelength range of 400~600 nm, indicating that the titanium ions contained are mainly Ti ⁴⁺ electronic configuration; in addition, it can also be found from Figures 13-14 that the addition of titanium salt will cause absorption The sidebands are blue-shifted, and the absorption intensity at the wavelength of 310 nm will also increase significantly, indicating that Ti ⁴⁺ ions will increase the absorption intensity. According to Table 4, it can be found that as the addition of titanium salt increases, the energy gap will increase. The reason for the increase in the aforementioned energy gap may be that the grain size will be refined as the addition of titanium salt increases, resulting in absorption edge With blue shift; also, according to Table 4, it can be found that compared with Comparative Examples 8-11 where urea is not added in the process, the energy gaps of Examples 1, 13, 15, and 17 where urea is added in the process will also increase. The increase in energy gap may be due to the fact that urea helps to refine the particle size.

＜X- Photoelectron spectrometer (X-ray photoelectron spectroscopy, XPS) analysis ＞

Analytical method

X-ray photoelectron spectrometer was used to analyze the powder products obtained in Examples 1 and 15, respectively. The Gaussian simulation diagrams of O1s are shown in Figure 15 (Example 1) and Figure 16 (Example 15). The curve III is the curve obtained by measuring the powder product by X-photoelectron spectrometer, curve I is the curve obtained by Gaussian simulation analysis and is the oxygen ion of the main lattice, and curve II is the curve obtained by Gaussian simulation analysis The curve is oxygen vacancy, and the integral ratio (A _I /A _II ) of curve I and curve II is summarized in Table 5 below. When A _I /A _{II is} smaller, it means there are more oxygen vacancies in the powder product; when A _I /A _{II is} larger, it means there are fewer oxygen vacancies in the powder product.

In addition, the result of Ti2p _3/2 energy level analysis of Example 15 by X-photoelectron spectrometer is shown in FIG. 17.

table 5 Example Urea concentration (U/Sn) (mole/mole) Titanium salt addition amount (mole/mole) A _I /A _II 1 3 0 2.65 15 3 0.03 2.41

Results and discussion The powder products obtained in Examples 1 and 15 were analyzed by X-ray photoelectron spectrometer, respectively. From the A _I /A _II data in Table 5, it can be seen that there was an A _I / A _I in Example 15 where titanium salt was added during the preparation process. A _{II is} smaller than that of Example 1 without adding activator, indicating that Ti ⁴⁺ will increase the oxygen vacancy of the powder product. It can be found from Fig. 17 that the electronic configuration of the titanium ion of the powder product obtained by adding titanium salt during the preparation process is mainly Ti ⁴⁺ , not Ti ³⁺ , which conforms to the aforementioned <ultraviolet light-visible light spectrum analysis>. result.

＜ Fluorescence Spectrometer (Fluorescence spectroscopy) analysis ＞

Analysis 1:

Analytical method

After analyzing the powder products obtained in Examples 1 and 12 with a fluorescence spectrometer, the relative intensity of the obtained excitation peaks (λ _em =550 nm) is shown in Figure 18; comparing Examples 1 and 2 with Comparative Example 1 After the powder product was analyzed by a fluorescence spectrometer, the relative intensity of the emission peak obtained (λ _ex =328 nm) is shown in Figure 19; the results obtained from Examples 1, 5 to 7, Comparative Examples 12 to 13 and Comparative Example 8 After the powder product is analyzed by a fluorescence spectrometer, the relative intensity of the emission peak obtained (λ _ex =328 nm) is shown in Figure 20.

Results and discussion It can be seen from Figure 18 that the powder products obtained in Examples 1 and 12 have obvious excitation peaks at wavelengths of 328 nm and 470 nm. The former is attributed to the transition of electrons between the energy bands of zinc-tin spinel, and the latter speculates It may be related to the lattice defects of the host. As with the results of the aforementioned <X-photoelectron spectrometer analysis>, the zinc-tin spinel lattice contains quantitative oxygen vacancies, so the excitation peak at wavelength 470 nm is derived from The oxygen gap between the energy gaps is caused by the absorption of the separation energy level; and the excitation intensity of Example 12 with titanium salt is higher than that of Example 1 without titanium salt. The reason for the increase in excitation intensity may be that Ti ⁴⁺ ions increase the wavelength The absorption intensity of 328 nm and Ti ⁴⁺ ion will increase the oxygen vacancy of the powder product, which is in line with the results obtained by the aforementioned <Ultraviolet-Visible Spectroscopy> and <X-Photoelectron Spectroscopy Analysis>. It can be seen from Fig. 19 that the powder products prepared at the annealing temperature between 1000 and 1200°C (Examples 1 and 2) are excited by ultraviolet light with a wavelength of 328 nm, except for a weak radiation peak at 390 nm. It has a significant emission wave in the range of 400~750 nm and the peak is 550 nm. It has blue and green light emission characteristics, and the luminous intensity will increase with the increase of annealing temperature, indicating that the luminous intensity can increase with the increase of crystallinity. The luminous intensity of the powder product prepared at the annealing temperature of 600°C (Comparative Example 1) has not yet formed zinc tin spinel crystals, so its luminous intensity is much lower than that of the powder products prepared in Examples 1 to 2, indicating that the comparison The powder product prepared by the preparation method with an annealing temperature lower than 700°C, and the powder product (zinc-tin spinel phosphor powder) prepared by the preparation method with the annealing temperature not lower than 700°C of the present invention will have higher The luminous intensity. It can be seen from Fig. 20 that, compared with Comparative Example 8 where urea was not added in the process, Examples 1, 5-7 where urea was added in the process and the urea concentration (U/Sn) was not higher than 5 had higher luminous intensity. Attributable to the fact that urea helps to reduce the agglomeration of the powder and to refine the particle size, the same as the result of the aforementioned Scanning Electron Microscope (SEM) analysis; and the comparison of the urea concentration (U/Sn) higher than 5 Examples 12 and 13 will reduce the luminous intensity, which may be caused by powder agglomeration and coarsening. As with the results in Table 2, the appearance of the gel with a urea concentration (U/Sn) higher than 5 is translucent (U/Sn= 7) or white (U/Sn=10), which may be related to the higher agglomeration of the colloidal particles; indicating that compared with the powder product prepared by the preparation method without adding urea in the process, the present invention adds urea and urea The powder product (zinc-tin spinel fluorescent powder) prepared by the preparation method with a concentration (U/Sn) not higher than 5 will have higher luminous intensity.

Analysis 2:

Analytical method

The emission spectra (λ _ex =328 nm) of the phosphor powder obtained in Examples 1, 13, 15, 17 and Examples 20 to 21 were measured with a fluorescence spectrometer, respectively, at a wavelength of 550 to 555 nm (λ _ex =328 nm), and the results are shown in the figure 21 shown. The Gaussian simulation diagram (λ _ex =328 nm) of the emission spectrum obtained in Example 15 is shown in FIG. 22.

Results and discussion It can be seen from Fig. 21 that compared with Example 1 where titanium salt is not added in the process, Examples 13, 15, 17, 20 to 21 where titanium salt is added in the process have higher luminous intensity, except for weak In addition to the near-ultraviolet radiation peak, there is a significant radiation wave in the wavelength range of 400~800 nm and the peak is 555 nm. It has broad visible light radiation characteristics, and the luminous intensity will increase with the increase of annealing time (Example 20 ~21); It is especially worth mentioning that when the addition amount of titanium salt (the molar ratio of titanium isopropanol to tetramethoxide tin) is 0.03 and the annealing time is 6 hours, the resulting powder The product will have the highest luminous intensity; it shows that compared to the powder product prepared by the preparation method without adding urea in the process, the powder product prepared by the preparation method of adding urea and adding titanium salt of the present invention (zinc tin tip The spar phosphor will have a higher luminous intensity, and increasing the annealing time will increase the luminous intensity. It can be seen from Fig. 22 that the powder product obtained in Example 15 has a weak emission peak at a wavelength of 370 nm and an obvious emission peak at a wavelength of 555 nm, and the peaks at a wavelength of 555 nm can be separated at 483 nm and 564 nm. And 672 nm. Among them, the emission peak at 483 nm can be attributed to oxygen vacancies, and the emission peak at 564 nm may be caused by the interaction of oxygen vacancies and point defects of Zn ²⁺ or Sn ⁴⁺ ions, while the emission peak at 672 nm is inferred It may be related to the interstitial defect of Sn ⁴⁺ or the vacancy of Zn ²⁺ .

Analysis 3:

Analytical method

Measure the relative intensity (λ _ex =328 nm) and decay time of the powder products obtained in Examples 1, 9 to 19 at wavelengths of 550 to 555 nm with a fluorescence spectrometer. The results are as follows: Table 6 Shown.

Table 6 Urea concentration (U/Sn) (mole/mole) Titanium salt addition amount (mole/mole) Relative Strength Decay time (ms) Example 1 3 0 0.21 4.2 Example 9 1 0.01 0.58 4.1 Example 10 1 0.03 0.71 4.0 Example 11 1 0.05 0.42 3.8 Example 12 3 0.005 0.46 4.1 Example 13 3 0.01 0.75 3.8 Example 14 3 0.02 0.88 3.9 Example 15 3 0.03 1.0 3.6 Example 16 3 0.04 0.73 3.5 Example 17 3 0.05 0.55 3.4 Example 18 3 0.07 0.35 3.2 Example 19 3 0.1 0.24 3.2

It can be found from Table 6 that under the conditions of the same annealing temperature and annealing time, the addition of titanium salt during the preparation process can increase the luminous intensity of the powder product (zinc-tin spinel phosphor); it is particularly worth mentioning However, under the condition of using the same urea concentration (U/Sn), when the addition amount of titanium salt (the molar ratio of titanium isopropanol to tetramethoxide tin) is 0.03, the powder produced The solid product will have the highest luminous intensity; in addition, the addition of titanium salt during the preparation process can reduce the decay time of the prepared powder product (zinc-tin spinel fluorescent powder), between 4.1~3.2 milliseconds (ms), With short afterglow characteristics.

＜CIE Chromaticity coordinate analysis ( λ _ex =328 nm)＞

Analytical method

The CIE 1931 chromaticity coordinates obtained in Examples 1, 13, 15, 17, and 21 after being excited by excitation light with a wavelength of 328 nm are shown in FIG. 23. Among them, the CIE 1931 chromaticity coordinate (analysis of CIE chomaticity diagram) in Figure 23 is calculated in accordance with the standard three primary colors and tristimulus values established by the International Commission on Illumination (CIE), and the fluorescence spectrometer measured The luminescence spectrum is converted into a chromaticity coordinate (X, Y) value, and the results are shown in Table 7 below, which are used to identify the relative relationship between the luminous color purity of the present invention and other colors of visible light.

Table 7 Urea concentration (U/Sn) (mole/mole) Titanium salt addition amount (mole/mole) CIE chromaticity coordinates Annealing time (hours) X Y Example 1 3 0 0.321 0.373 2 Example 13 3 0.01 0.342 0.354 2 Example 15 3 0.03 0.373 0.331 2 Example 17 3 0.05 0.334 0.332 2 Example 21 3 0.03 0.382 0.323 6

Results and discussion From Fig. 23 and Table 7, it can be found that the CIE chromaticity coordinate values of Examples 1, 13, 15, 17 and 21 are all within the CIE chromaticity coordinate values with near-white light emission characteristics (X=0.321~0.382, Y =0.323~0.373). Therefore, it can be seen from the foregoing description that regardless of the amount of titanium salt added, the preparation method of the present invention can produce a powder product with near-white light emission characteristics (zinc tin spinel phosphor powder), and the addition of titanium salt can increase the luminous intensity And improve the color rendering of white light. It is particularly worth mentioning that the zinc-tin spinel fluorite powders (Zn ₂ Sn _1-x Ti _x O ₄ , x=0.03) prepared in Examples 15 and 21 with a titanium salt addition amount of 0.03 are closer to The color rendering characteristics of white light.

In summary, since the preparation method of the present invention uses the tin alkoxide as the source of tin and a specific amount of urea is added as a hydrolysis aid in the process (the molar ratio of urea to tin alkoxide is not higher than 5), It can promote the hydrolysis reaction and greatly improve the dispersibility and homogeneity of the sol, so that the preparation method of the present invention does not need to add ethylene glycol methyl ether as a gelling agent and can promote the progress of the condensation polymerization reaction to shorten the gelation time. The zinc-tin spinel fluors powder has a lower chance of agglomeration and a smaller average particle size, which can increase the near-white luminescence intensity of the zinc-tin spinel fluors powder, and the preparation method of the present invention adds a specific amount of titanium as an activator Salt can further refine the particle size of the zinc tin spinel phosphor powder, increase its luminous intensity, and further increase the near-white color rendering of the zinc tin spinel phosphor powder, so it can indeed achieve the purpose of the invention.

However, the above are only examples of the present invention. When the scope of implementation of the present invention cannot be limited by this, all simple equivalent changes and modifications made in accordance with the scope of the patent application of the present invention and the content of the patent specification still belong to Within the scope of the patent for the present invention.

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: Figure 1 is an X-ray diffraction diagram illustrating the X-rays of Examples 1 to 4 and Comparative Examples 1 to 3 Diffraction spectrum; Figure 2 is an X-ray diffraction diagram, illustrating the X-ray diffraction spectra of the products of Comparative Examples 4 to 8; Figure 3 is an X-ray diffraction diagram, illustrating Examples 1, 13, 15, and 17. Figure 4 is a Raman spectrum diagram illustrating the Raman spectrum of Comparative Example 8; Figure 5 is a Raman spectrum diagram illustrating the Raman spectrum of Example 1; Figure 6 is a Raman spectrum diagram Spectrogram, illustrating the Raman spectrum of Example 15; Figures 7-12 are SEM photographs respectively illustrating Comparative Example 7 (Figure 7), Example 2 (Figure 8), Example 8 (Figure 9), and Comparative Example 8 (Figure 10), the appearance of Example 1 (Figure 11) and Example 15 (Figure 12); Figures 13 to 14 are absorption spectra, respectively, illustrating Comparative Examples 8 to 11 (Figure 13) and Example 1. The absorption spectra of 13, 15 and 17 (Figure 14); Figures 15 to 16 are respectively a Gaussian band deconvolution diagram, respectively illustrating the X-ray of Example 1 (Figure 15) and Example 15 (Figure 16) The Gaussian curve of the photoelectron spectrum; Fig. 17 is a graph showing the results of the Ti2p _3/2 energy level analysis of Example 15 by an X-photoelectron spectrometer; Fig. 18 is a graph showing the same as those of Examples 1, 12. Excitation spectrum (λ _em =550 nm); Figure 19 is a graph illustrating the emission spectra of Examples 1, 2 and Comparative Example 1 (λ _ex =328 nm); Figure 20 is a graph illustrating Example 1 , 5~7, the emission spectra of Comparative Examples 12-13 and Comparative Example 8 (λ _ex =328 nm); Figure 21 is a graph illustrating the emission spectra of Examples 1, 13, 15, 17, 20-21 ( λ _ex =328 nm); Figure 22 is a graph illustrating the Gaussian simulation diagram of the emission spectrum obtained in Example 15 (λ _ex =328 nm); and Figure 23 is a CIE 1931 chromaticity diagram illustrating Example 1, respectively The chromaticity coordinates of 13, 15, 17, 21 are excited by excitation light with a wavelength of 328 nm.

Claims (10)

A method for preparing zinc-tin spinel phosphor powder includes the following steps: step (1), preparing a precursor liquid, and the precursor liquid contains zinc salt, tin alkoxide and a solvent; step (2), adding to the precursor liquid And hydrolyze urea to obtain a transparent sol, wherein the molar ratio of the urea to the tin alkoxide is not higher than 5; step (3), subject the transparent sol to a condensation polymerization reaction to obtain a transparent gel; And step (4), drying the transparent gel, and performing annealing treatment at a temperature not lower than 700°C to obtain zinc-tin spinel fluorescein powder, and the experimental formula of the zinc-tin spinel fluorescein powder is Zn ₂ Sn _1–x Ti _x O ₄ , 0≦x≦0.1. The method for preparing zinc tin spinel phosphor powder according to claim 1, wherein, in the step (1), the molar ratio of the zinc salt to the tin alkoxide is 2. The method for preparing zinc tin spinel fluorescer powder according to claim 1, wherein the zinc salt is selected from zinc nitrate, zinc acetate or a combination of the foregoing, and the tin alkoxide is tetramethoxide tin. The method for preparing zinc-tin spinel fluorescein powder according to claim 1, wherein, in this step (2), it further comprises adding a titanium salt before adding the urea. The method for preparing zinc-tin spinel phosphor powder according to claim 4, wherein, in the step (2), the molar ratio of the titanium salt to the tin alkoxide is in the range of 0.005 to 0.05. The method for preparing zinc tin spinel fluorescer powder according to claim 5, wherein, in the step (2), the molar ratio of the titanium salt to the tin alkoxide is in the range of 0.01 to 0.05. The method for preparing zinc-tin spinel phosphor powder according to claim 6, wherein, in the step (2), the molar ratio of the titanium salt to the tin alkoxide is 0.03. The method for preparing zinc-tin spinel phosphor powder according to claim 1, wherein, in this step (3), an annealing treatment is performed at a temperature greater than 800°C. The method for preparing zinc tin spinel phosphor powder according to claim 8, wherein, in this step (3), annealing treatment is performed at 1000 to 1200°C. The method for preparing zinc-tin spinel fluorescer powder according to claim 1, wherein, after the zinc-tin spinel fluoresce powder is excited by excitation light with a wavelength of 328 nm, the X-coordinate value of the CIE chromaticity coordinate will be 0.321 Radiation light in the range of ~0.382 and the Y-axis coordinate value in the range of 0.323~0.373.

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