CN1062318C

CN1062318C - Method and device for growing diamond of aureoviridae family

Info

Publication number: CN1062318C
Application number: CN97106365A
Authority: CN
Inventors: 吴光照; 朱妆德; 颜声辉
Original assignee: Shanghai Institute of Optics and Fine Mechanics of CAS
Current assignee: Shanghai Institute of Optics and Fine Mechanics of CAS
Priority date: 1997-04-08
Filing date: 1997-04-08
Publication date: 2001-02-21
Anticipated expiration: 2017-04-08
Also published as: CN1195717A

Abstract

A method and device for growing a diamond of the family of emerald gems. The family of aurora includes aurora, aurora and alexandrite. These three gemstones are mainly used for ornamental purposes. The growth method of the invention is a rotary temperature gradient method, and the growth device is a rotary temperature gradient furnace. The method is characterized in that the crystal growth process is from the bottom of the melt to the top, the crucible can rotate or move up and down, the rotation of the crucible can fully mix the melt in the melt, the required impurities are supplemented or supplemented from the top of the crucible, and the grown gem crystal is high-quality. The equipment is relatively simple, and the ratio of output to input is high.

Description

Method and device for growing diamond of aureoviridae family

The present invention relates to a method for growing a decorative gemstone of the family of emerald gemstones and a device thereof. The Chrysoberyl family of crystals include Chrysoberyl Cat's Eye, Chrysoberyl (English name Chrysoberyl) and Alexandrite (Alexandrite), and are mainly suitable for the decoration industry.

The prior art is as follows: the precious stones which people enjoy are few in natural resources and expensive in price, so people try to artificially grow in the twenty-century and the fortieth years by various methods. The methods used include the melting method (fusion), the melt method (molten solvationchnique), the hydrothermal method (hydrothermal), the flame method (vemeuil method) and the flux method (flux method). However, the primary crystals of the gemstones obtained by the methods are very small and have no growth significance. Specific details can be found in G.A. Bukin et al, "Growth of Alexandrite Crystals and investment of the Properties", journal of Crystal Growth, 52 (1981), 537-541. North-Holland publishing company, page 537, section 1; section 3, page 539; and E.F. Farrell et al, "Flux Growth of Chrysoberyl and Alexandrite", J.Amer.Ceramic Soc, 47(1964) 274-276. at the end of the seventies of the twentieth century, growing the subtransk amethyst by Czochralski Method and obtaining high technology application was started; see J.C. walling et al, "Tunable Alexandrite Lasers" IEEE journal of Quantum Electronics, QE16(12), (1980) 1302-1315, section 2, page 1304. But is not used as an ornament jewel due to high cost. In 1994, Shanghai ray machine of Chinese academy of sciences began to provide ornamental gem of Maili mountain Dai Cui Shi, Shen honor Shu (dictionary of Chinese practical scientific and technological achievements, southwest university of transportation Press, 1994 version, 617, 12020901 item "laser crystal and gem"; the Czochralski method is also used for growth.

The pulling method is that the raw materials are put into an iridium crucible to be melted into a melt, the seed crystal is contacted with the surface of the melt at a proper temperature, and then the growing crystal is slowly pulled upwards. The crystal diameter is limited to 1/3-1/2 of the crucible caliber, and only 1/4 of raw material can be drawn into crystals usable for color. In addition, the Czochralski method has complex equipment and strict technical requirements, so the Czochralski method is used for producing the civil Aries amethyst alexandrite, has low output/input ratio and is not beneficial to batch production. Which is a disadvantage of the prior pulling method. Furthermore, it is difficult to produce aurora viridiflaves by the czochralski method because the valence state of the doped titanium ion is not optimally controlled. Therefore, no human has produced aurora and aurora to date.

The invention aims to grow civil aureogreen opal, aureogreen gem and Alexandrite by adopting a rotary thermal gradient method (RTG) and a rotary temperature gradient furnace, thereby achieving the purpose of batch production. Mainly solves the synthesis technology of the aurora and solves the batch production problem of civil aurora and alexandrite, and overcomes the defects and problems in the prior art.

The device used by the invention is an improved temperature gradient single crystal furnace with a rotary moving mechanism 14, which is called a rotary temperature gradient furnace. FIG. 1 shows the internal structure of a rotary temperature gradient furnace body. The crucible 1 used therein can be made of molybdenum ingot, the diameter of which corresponds to the diameter of the desired primary crystal and the height of which is greater than the length of the primary crystal. The inner cylindrical surface of the crucible 1 has a slope of 1: 100, so as to be beneficial to pouring out the primary crystal; the bottom of the crucible 1 is provided with a small well 2 for placing seed crystals. In addition, a cruciblecover 3 is provided, and the crucible cover 3 with no holes or different opening sizes is used according to different jewels to control the influence of the furnace atmosphere on the crystal growth. The crucible 1 contains a raw material melt 4. The crucible 1 is placed on the crucible holder 5 supported by the crucible rod 6, the crucible rod 6 is provided with the rotation moving mechanism 14, and the rotation moving mechanism 14 can make the crucible holder 5 rotate together or move up and down with the crucible 1. The rotation speed R = 0-100R/min. The crucible 1 is placed in a heating element 7, and the heating element 7 can be made of high purity graphite and is shaped like a cylinder of a rectangular wave-shaped energizing circuit, as shown in fig. 2. The heating body 7 is powered by an electrode 13 on an external power supply and a graphite electrode clamping plate 8 connected with the heating body 7. A support ring 9 made of corundum tubes supports the electrode holder 8. The temperature control thermocouple 10 and the temperature thermocouple 11 are tungsten-rhenium thermocouples and respectively extend into the vicinity of the heating body 7 and the vicinity of the bottom of the crucible 1. In order to achieve the necessary high temperature, the upper, lower and periphery of the heating body 7 are provided with heat preservation screens 12, and the heat preservation screens 12 can be made of molybdenum sheets.

The specific process of growing the crystal is as follows:

the basic dynamic process of the synthesis of the three gemstones is similar. Their basic raw materials are also the same, i.e. Al₂O₃Unlike BeO, except for the impurity incorporated. Firstly, selecting high-purity raw material Al₂O₃And BeO and the impurity source material doped. Important is the treatment of the BeO feedstock. The present invention treats BeO (including briquetting and weighing) separately in a closed box system,without Al₂O₃Mixing (i.e. not mixing) ensures that the protection range is reduced. Al (Al)₂O₃Mixed with the doped impurities only and then pressed into blocks. The purity of the raw materials is 99.99 percent. The raw material formula is calculated according to the following formula:

(1) golden green opal:

(2) a golden emerald:

(3) arietia mountain purple jade stone:

wherein x =0 ~ 0.1, y =0 ~ 0.2, t =0 ~ 0.01, u =0 ~ 0.01. Weighed TiO₂Preferably, it is reduced to Ti₂O₃And then reused.

Firstly, seed crystals are put into the small well 2 at the tail part of the crucible 1, or not put. Then, the prepared raw material blocks are loaded into the crucible 1, and the crucible cover 3 is covered. Vacuumizing the furnace until the vacuum degree reaches 10^-5After the device is arranged in the middle of the furnace, high-purity argon with certain pressure is filled. Slowly heating to 1900 ℃ to melt the raw materials, and rotating the crucible 1 at a rotation speed of about 10-20 rpm to mix the molten materials. Finally, the grown crystal is cooled according to the program. The temperature control is realized by a YC series precise program temperature controller.

The key point of the invention is to grow the crystal starting from the bottom of the melt. This is very advantageous for the successful growth of the chrysophyte family crystals with greatly different raw material specific gravities. In addition, the reducing atmosphere carbon monoxide isgenerated in the furnace, which is beneficial to the trivalent Ti impurities to enter crystal lattices to synthesize the opal.

The method is a rotary temperature gradient method, wherein the rotating speed R = 0-100R/min; when R =0, the temperature gradient method is used. When the crucible 1 is lowered by the crucible rod 6 to grow the crystal, the lowering method is called. Also, heat exchange methods grow crystals starting from the bottom of the melt. In order to meet the requirements of the color and the tone of the gem, the doped impurities comprise V, Cr, Mn, Fe, Co, Ni and Ti, and the doping concentration is in the range of 0-50 at%. In order to improve the yield and the color uniformity, the continuous feeding and impurity adding are carried out from the upper part of the crucible 1, which also belongs to one of the characteristics of the invention. Post-treatment of the crystal, i.e. annealing process, is important for gemstones. Taking out the grown crystal, cutting into slices, and annealing; the annealing temperature T is more than or equal to 1000 ℃, and the holding time T is more than or equal to 24 hours; the annealing is carried out in air or by introducing oxygen simultaneously. Post-treatment of the annealed crystals grown in the present invention is also unique and is more essential in the production of aurora and emerald.

The invention has the advantages that: the rotary temperature gradient furnace and the rotary temperature gradient method adopted by the invention are the best methods for producing the three civil decorative gems which belong to the same aureoviride mineral family. The crystal growth process starts from the bottom of the melt, and the crucible rotates to fully mix the raw material melts with different specific gravities, so that the yield is improved; impurities or raw materials can be continuously added from the open pore of the crucible cover 3, which is beneficial to the mass production of the jewel with high quality. With this advantage, the industry blank has been filled up. The equipment is relatively simple and the output/input ratio is high. The influence of the furnace atmosphere on the crystal growth can be properly controlled. Especially, the aurora green opal is beneficial to the entry of Ti into crystal lattices by using the method disclosed by the invention to form the cat eye effect. Three precious stones, namely auryl-green opal, auryl-green precious stone and illite, are rare special precious stones and are expensive; the civil market is wide in quantity.

Description of the drawings:

FIG. 1 is a schematic view of a rotary temperature gradient furnace used in the present invention

FIG. 2 is a schematic view showing the shape of the heating element 7

Example 1: growth of aurora viridis

Selecting raw material Al₂O₃And BeO 99.99% pure, doped Fe₂O₃And TiO₂The purity was 99.9%. First TiO is added₂High-temperature reduction treatment is carried out in hydrogen to generate Ti₂O₃And (5) standby. The formula is calculated as follows:

wherein x =0.005 and y = 0.04-0.08;

weighing the Al₂O₃、Fe₂O₃And reduced TiO₂And mixing and briquetting. And the BeO is independently pressed into blocks and weighed in a sealed operation box. A molybdenum crucible 1 of phi 80x180mm was used. Firstly, c-axis BeAl is added₂O₄The seed crystal is put into the small well 2 at the bottom of the crucible, or not put. Then pressing with Al₂O₃---BeO---Al₂O₃---BeO---Al₂O₃Alternately adding, and finally adding all the residual Al₂O₃The raw material pieces are charged into the crucible 1. The crucible cover 3 with two phi 1Omm through holes is covered. The furnace chamber is vacuumized to 10^-5After the reaction was started, pure argon gas was introduced. The temperature is automatically increased to 1900 ℃ indicated by a temperature thermocouple, the raw material in the crucible 1 is changed into melt, the crucible is rotated, the rotating speed R = 16R/min, the crucible is rotated for two minutes and is stopped for one minute, and the operation is repeated for six times.Then, the temperature is reduced according to the program to grow the crystal, and the temperature reduction rate is 2.5 ℃/hour. And in the growth process, the rotating speed of the crucible R = 28R/min (or not). The furnace was cooled to room temperature over a further 16 hours.

The crystal taken out is cut into slices with the thickness of 1.2cm, and the slices are put into a muffle furnace for annealing in air (oxygen can also be introduced). The annealing temperature T = 1200-1300 ℃, and the annealing time T =24 hours.

Example 2: growth of aureobasidium

Selecting raw material Al₂O₃BeO has a purity of 99.99%, and the contents of impurities including Ca, Mg, Na and Si are not more than 80ppm, 100ppm and 80ppm, respectively. The purity of Fe2O3 was 99.9%. The formula is calculated as follows:

(1-x)Al₂O₃+xFe₂O₃+BeO=Fe∶BeAl₂O₄wherein x = 0.005-0.01. Weighing the Al₂O₃And Fe₂O₃Mixing, briquetting, BeO pressing aloneAnd (5) blocking and weighing. The crucible, seed crystal and method of placing the seed crystal, and charging of the raw material block were the same as in example 1. The crucible cover 3 without holes is covered. The following steps of evacuation and inflation to the annealing process are also the same as in example 1.

Example 3: growth of Arietaria amethystoides

Selecting raw material Al₂O₃And BeO with a purity of 99.99% and containing impurities of Ca, Mg, Na and Si of not more than 100ppm, respectively. Cr (chromium) component₂O₃The purity of (2) was 99.9%. The formula is calculated as follows:

wherein t = 0.0012-0.0016, and u = 0-0.0018.

The following procedures such as weighing of raw materials and the like were all the same as in example 2, but annealing of the obtained crystal was not necessary.

Claims

1. A method for growing the decorative jewel of aureobasil family includes such steps as growing crystal from the seed crystal at the bottom of molten body, and rotating the molten body by rotary temp gradient method.

2. The method for growing a sapphire family ornamental gemstone according to claim 1, wherein the specific raw material formulation for growing the aurora, the emerald and the illite is: [1]the aurora is:

[2]the diamond is:

[3]the Aries majorana purple emerald alexandrite is:

in the above formula, x =0 to 0.1, y =0 to 0.2, t =0 to 0.01, and u =0 to 0.01.

3. The method for growing a sapphire family of ornamental gemstones according to claim 1 or 2, characterized in that the specific procedure is mainly:

[1]selecting high-purity raw material Al₂O₃Weighing, mixing and briquetting the mixture with doped impurities;

[2]selecting a high-purity raw material BeO, independently briquetting and weighing in a closed operation box;

[3]putting the prepared raw materials into a crucible (1);

[4]vacuumizing the furnace until the vacuum degree reaches 10^-5When the device is arranged in a torr state, argon is filled;

[5]heating in the furnace to melt the raw materials to form a melt (4); rotating the crucible (1) to mix the molten material in the melt (4), wherein the rotation speed R of the crucible (1) is more than 0 in the growth process;

[6]cooling the grown crystal according to the program, cooling the temperature to room temperature, and taking out the crystal after the growth is finished;

[7]annealing treatment is carried out on the aurora and the aurora, the annealing temperature T is more than 1000 ℃, the annealing time T is more than or equal to 24 hours, and annealing is carried out in the air or oxygen is introduced.

4. The growing apparatus for use in the method of growing a sapphire family ornamental gemstone according to claim 1, wherein the furnace body comprises a crucible (1) disposed in a heating element (7), a crucible holder (5) supported by a crucible rod (6) is provided with a crucible (4) for holding a raw material melt and covered with a crucible cover (3), the bottom of the crucible (1) is provided with a well (2) for holding a seed crystal, the heating element (7) is provided with an electrode holder (8) and an electrode (13) supported by a support ring (9) for connection with an external power source, the upper and lower peripheries of the heating element (7) are provided with heat-insulating shields (12), a temperature-controlling thermocouple (10) and a temperature-measuring thermocouple (11) are provided adjacent to the bottom of the heating element (7) and the crucible (1), characterized in that the crucible rod (6) supporting the crucible holder (5) and the crucible (1) is provided with a rotational movement mechanism (14) capable of driving the crucible (1) to rotationally, so the furnace is called a rotary temperature gradient furnace.

5. The growing apparatus for use in the method for growing a sapphire family ornamental gemstone according to claim 4, wherein the rotation speed of the rotary temperature gradient furnace R =0 to 100 rpm.