JPS60231487A - Manufacture of raw material for growing single crystal - Google Patents

Abstract

PURPOSE:To obtain the titled raw material capable of providing a single crystal not contg. any bubbles and having excellent transparency and gloss by compression-molding the raw material power of Al2O3 which is obtained by treating Al(OH)3 at high temps. under vacuum into a round rod, and sintering the rod. CONSTITUTION:Al2O3 which is obtained by treating Al(OH)3 at 1,000-1,200 deg.C and 10<-1>-10<-5>Torr degree of vacuum is used as the raw material powder of a corundum crystal, an alexandrite crystal, and spinel crystal, and a colorant such as Cr2O3, NiO, Fe2O3, and TiO2 is added to the powder and sufficiently mixed. The mixture is then compression-molded into a round rod, and sintered in an electric furnace to obtain the raw material for growing the single crystal with the infrared-condensing floating zone method (FZ method). The raw material is then suspended from the upper shaft of an FZ device,and a seed crystal provided to the lower shaft is heated to form a melt between the raw material and the seed crystal. A single crystal is grown on the seed crystal by moving both raw material and seed crystal downward at 4.0mm./H growth rate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention is a raw material manufacturing method for growing a single crystal by a floating zone method using alumina synthesized from aluminum hydroxide (At(OL)3).

[Prior art]

Conventionally, the floating zone method (hereinafter referred to as the FZ method) has been widely used in research on newly synthesized crystals because it is said to be able to easily synthesize newly created crystals in a short time. 4
There are also numerous patents related to new methods of growing these crystals. However, there is very little about the quality of crystals, and crystals grown using the #method tend to have many defects, and among them, temporary defects that can be observed with the naked eye are a big problem, and crystals used for jewelry are This prevents the original reflection and refraction of light, and has transparency, which is important for jewelry.
This is a major cause of the decrease in the value of gemstones.

〔the purpose〕

The present invention has been made to solve the above problems, and its purpose is to create a crystal using alumina as a raw material. Use things+tll,
The object of the present invention is to provide a method for producing raw materials for synthesizing bubble-free crystals grown by the FZ method.

(Requires 1!f) In the method of growing a single crystal from a melt, the present invention provides a method for growing a single crystal from a melt when alumina (AtzOa) is used as the raw material powder for the stem liquid.
)l'lx)? It is characterized in that it is treated at a high temperature of 1000° C. to 1200° C. and a vacuum degree of 101 Torr to Ilr”rorr and is used as a material by the fFZ method.

The treatment temperature range of 61,000 DEG C. to 1,200 DEG C. in the present invention is optimal; below 1,000 DEG C., water and adsorbed gas are dissociated and removed, and conversion to alumina is insufficient, resulting in little effect. At 1200° C. or higher, conversion to alumina is sufficient, but secondary particles are formed, the particle size increases, and sinterability decreases, so the above range is desirable.

Vacuum in the present invention Hu 101Torr ~ 10-'
Torr is optimal; below 10-1Tnrr, it is ineffective in removing moisture and adsorbed gas;
There is no change in the removal of adsorbed gas on the r-hannel, and the effect is the same. Therefore, the above-mentioned range is desirable.

The alumina raw material in the present invention is used for single crystal growth by the FZ method. In the case of corundum crystals, the main raw material is alumina, and the coloring agents are nichrome oxide for ruby, nichrome oxide and nickel oxide for lattia, and ferric oxide and titanium oxide for blue to fire. The mixed powder is thoroughly mixed in an alumina mortar, packed into a rubber tube, and pressure-molded into a 9n9 shape using a rubber press. The molded body is then sintered in a lightning furnace and used as a raw material for single crystal synthesis by the FZ method. However, by using the alumina raw material described above, it is possible to eliminate air bubbles without affecting the type and behavior of the blue agent. No crystals can be total synthesized.

In the case of alexandrite crystals, the above-mentioned alumina raw material was used in the same way, and a predetermined amount of beryllia was added, nichrome oxide and ferric oxide were added as coloring agents, and the mixture was mixed well in a mortar. If it is sintered by the FZ method and used as a raw material for single crystal synthesis by the FZ method, bubble-free crystals can be synthesized regardless of the type and content of the colorant.

In the case of spinel crystal, the aluminum + [4? Add an equimolar amount of magnesy/(Mσ0) to m and ζ, and add v as above.
When used as a raw material for single crystal synthesis using the Cyz method, a bubble-free crystal can be synthesized.

Using the alumina raw material of the present invention, raw material rods such as corundum, alexandrite, and nuvinel crystals, which are grown into round rods with a diameter of 8 wl to 101111 mm, are placed in an FZ system (infrared heating single crystal manufacturing equipment). Suspended from the shaft of the F section, seed crystals are placed on the lower shaft, heated, a molten body is formed between the raw material and the seeds, and both of them are simultaneously moved downward at the speed of one foot, moving and filtering the seeds. Grow crystals on top of crystals.

The downward movement speed at this time, that is, the growth speed is 40 m/H.
In the above case, air bubbles are included in the crystal, and 4.01i
Less than I/H is desirable.

[Example 1] Reagent grade (purity 999% or higher) aluminum hydroxide 4
057 into a platinum crucible and heated to a temperature of 1200 in a vacuum furnace.
°C? , *, empty tf, 1.5 for the raw material treated for 4 hours at -1O-2Torr? Add D4 reagent special grade nichrome oxide, add Guiflon in an alumina mortar and mix well. After drying, the #209f mixture was packed into a rubber tube with an inner diameter of 10 mm, one end of which was sealed, and molded for about 15 minutes at a pressure of 1 toniσ2 without a rack at -7°. ζ et al., the forming raw material rod was suspended in an alumina tube with a platinum wire to prevent contamination from the heater, and was heated at 170 m using a box-type electric furnace.
Sintering was performed at 0°C for 20 hours.

The sintered rod with an outer diameter of 8 mm and a length of about 70 mm obtained by the above operation was fixed to the upper shaft of an FZ device using an infrared concentrated heating method, seed crystals were fixed to the lower shaft VC, and the raw material was transferred using a 5-quartz glass tube. Separated the seed from the outer world and let air flow through it as an atmosphere. Then, heat is applied to form a molten part at the opening of the raw material and the seed, and the raw material and the seed are simultaneously moved downward at a speed of 1,000 feet to grow crystals.
Ta.

The growth conditions for ruby single crystals are shown below.

Fast growth; 2,0 night V') T Upper shaft rotation speed: 45 Q Lower shaft rotation speed: 15 rp1n Seed: Corundum single crystal Atmosphere: Empty Flow rate 40t7 Nara Iga growth time: 20 hours Grow by the above method The crystal had a round rod shape with a diameter of 40 mm and a diameter of 8 mm, and was a high-quality ruby single crystal with no bubbles observed even under a 20x magnification microscope.

[Example 2] Aluminum hydroxide fr@
231 g of alumina converted by processing at 1000°C and vacuum rl 10-” Torr for 4 hours and reagent special grade (purity 9
Place Beryllia 5.67.9 (more than 95) in a mortar, add special grade nichrome oxide 0,149 and ferric oxide tO91j as a VC coloring agent, and prepare the following [Example 1] ] A sintered raw material rod is made by the same method as
(Example 1) Alexandrite single crystal was grown using multiple growth conditions similar to λ.

The crystal grown by the above method was a round rod shape with a length of 40 m1+ and a diameter of 8 dragons, and was a high-quality alexandrite crystal with uniform color throughout and no bubbles observed due to microscopic casting VC of 20 times. [Effect] As stated above. According to the present invention, when growing a single crystal from a melt, the alumina raw material essential for crystal synthesis is aluminum hydroxide (xt(oH)sl of 10006C to 120C).
At high temperature of 0℃, degree of vacuum 10-' Torr ~10-'
By synthesizing at Torr, the growth rate is 1.0 mm/H faster than when using continuous α-alumina f using the FZ method, regardless of the type and amount of colorant, and no bubbles are generated. It is not inferior in terms of quality, and has great effects in improving productivity as an artificial jewelry and as an electronic material.

that's all Applicant: Suwa Seikosha Co., Ltd. Agent Patent Attorney Mogami

Claims (4)

[Claims] (1) In the method of growing a single crystal from a melt, when alumina (At, o3) is used as the raw material powder of the melt, the alumina is replaced with aluminum hydroxide 1Az (oH)3.
1. A method for producing raw materials for single crystal growth, characterized by using materials that have been completely wetted and treated in vacuum. (2) As mentioned above, the high temperature range is 10008C to 1200C, and the vacuum #10-'TOrr to 10' TOrr
A method for producing a raw material for single crystal growth according to claim 1, which is within the scope of claim 1. (3) The raw material manufacturing method for single crystal growth according to claim 1, wherein the raw material manufacturing method is for single crystal synthesis using an infrared condensing floating zone method. (4) The crystallization is performed in 4. Claim 11j characterized in that single crystallization can be omitted at a growth rate of less than OmJH.
Raw material manufacturing method for single crystal growth described in iK