JPS6077190A - Method for synthesizing single crystal by flux method - Google Patents

Abstract

PURPOSE:To obtain efficiently a single crystal, by using a raw material for a raw material component having a specific sintering density. CONSTITUTION:A raw material for the aimed single crystal component is sintered to give a base material having 0.1-10mu particle diameter and 60-99% sintering density. The resultant base material and a flux, e.g. an oxide or fluoride, are melted to synthesize the single crystal of the oxide or fluoride, etc. different from the flux component by the temperature difference or annealing method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently synthesizing single crystals using a flux method.

BACKGROUND ART Gemstones such as ruby and alexantite have recently attracted attention as crystals for laser oscillation. The pulling method, hydrothermal synthesis method, flux method, etc. are known as methods for synthesizing these single crystals. Because it has the drawback of being very expensive, the flux method is often used, especially when precise crystal synthesis is desired.

Mizumoto RA aims to improve carved crystal synthesis using this flux method.

Short crystal synthesis by flux method is P/10, B2
O3, V2O5, PbF2, Nα3A/3F6, etc. are dissolved in the target single crystal component matrix, and pain 1
There is no need to elaborate any further on the fact that this is a method of precipitating single crystals from syflux based on the difference in solubility depending on the temperature. Since the Wi solubility of the melon crystal component with respect to flux is generally not so large, the dissolution of the melon crystal component base material of the flux must always be supersaturated in order to grow large and large quantities of sin crystals.

The shortest way to increase the degree of supersaturation is to increase the temperature gradient between the decomposition part of the short crystal component and the growth part of the red crystal, but this temperature gradient is the greatest driving force in single crystal growth. If it is larger than a certain level, the following drawbacks will occur.

(1+ The quality of the crystal deteriorates. In other words, stacking faults are less likely to occur, and so-called inclusions are more likely to occur.)

i21 In addition to the intended growth on the seed crystal, a large number of microcrystals are generated due to natural nucleation, adhere to the seed crystal, and crystallize into a single strip.

In order to compensate for these drawbacks, it is necessary to increase the supply of single crystal component base material without increasing the temperature gradient. It is said that the volume into which the single crystal component base material is placed is desirably 10q6 or less in order to stably grow the single crystal, relative to the size of the brim into which the flux is placed.

The present invention is to sinter a single-crystal component base material into a porous state to facilitate the dissolution of the single-crystal component into a flux, thereby achieving stable and precise single-crystal growth.

The sintered density of the base material is between 60 and 99 inches, preferably
It is 70 to 95 inches.

If the sintered density is less than 60%, the shape will collapse as it is dissolved in the flux, and the specific surface area will become smaller.
If the 99% LD is large, the specific surface area is not much different from the bulk, which does not meet the purpose of the present invention.

In addition, powder is used as the base material, and its particle size is O,1~1
11 microns, preferably 0.5-5 microns.

0.] If particles smaller than microns are used for sintering, the secondary particles will not be raw, resulting in 0. ] Particles larger than 10 microns are meaningless because they have a diameter of microns or more, and particles larger than 10 microns greatly reduce the sinterability and decrease the specific surface area, which does not meet the purpose of the present invention.

The external shape of the sintered body is basically arbitrary, but it is desirable that the size is about 1/3 to IJ+ with respect to the inner diameter of the sintered body.
If it is larger than /3, the amount of the single crystal component base material is too large compared to the flux amount, and if it is smaller than ]A1, the external shape tends to be distorted due to consumption of the base material, and the specific surface area becomes small. Undesirable.

The effects of the present invention are shown below.

(11 The dissolution rate is large and constant.

It is porous because the sintered dense layer is kept relatively low.
It has a large specific surface area and can quickly dissolve the reduced amount consumed in single crystal growth into the flux. Further, even if the base material is consumed, the specific surface area remains constant, so the supply of raw materials can be kept constant, and as a result, the crystal growth rate can be kept constant.

(21 Crystal growth rate can be controlled.

The specific surface area can be changed depending on the degree of sintering.

That is, the amount of raw material supplied can be controlled, and the crystal growth rate can be controlled by the degree of sintering.

(31 Good quality crystals are obtained.

Crystal growth generally follows the following formula.

% Formula % ΔT: Temperature difference between the base material part and the crystal growth part M: Amount of base material supplied to the crystal growth surface As mentioned above, the purpose of the present invention is to reduce ΔT as much as possible to improve the quality of the crystal. Moreover, the aim is to achieve crystal growth at an industrial level.

That is, in the present invention, by setting the sintered density to 6 to 9 degrees, the supply of the base material can be increased and kept constant. This increases M, so △T′ft
Since it can be made smaller, the quality of the crystal can be improved.

Next, examples of the present invention will be shown below.

Example] Alexandrite single crystal growth> B (30: A, 4203 = l: l (molar ratio) powder KCr2O32wt% was mixed and sintered by rubber pressing to create a base material of 1 (IIIJIφ). .

This base material was placed in a platinum tank (60Uφ x 150m) at 80F, and V2O, 7009k was added as a flux and heated.

The sintered density of the base material was divided into three levels: 70 cm, 80%, and 99.9%, and crystal growth was performed under the same temperature conditions. In addition, a 3 vux square natural criberyl seed crystal was suspended from a platinum wire and placed in the growth area.

Temperature of base metal part: 980°C Temperature of crystal long acid part: 970°C, 975°C holding time: 1o
oo Time Growth Results (Growth Amount of) The obtained crystals were judged by microscopic observation and X-ray rocking curve. When ΔT was 10°C, the growth amount was large, but there were many inclusions and twins, and the quality was poor. When the temperature was 5°C, the quality was better than ΔT = 1υ°C, but the growth rate was faster when the sintered density was 70% and 80 cm.

Example 2 Ruby wheel crystal growth> 3 wt'16 Cr2O3 was added to AA203, mixed well, and sintered to the same size as in Example 1. 6016mm
A sintered base material of 80 mm was placed in a platinum crucible of 150 m in diameter, and 1.5 Hf of flux of Pbo:PbF2=l:5 (mole ratio) was added and heated to bring the temperature of the base material to 110 mm.
The temperature was maintained at 0°C and the growth zone temperature at 1090°C for 1000 hours.

A 1 cm square sapphire plate was used as a seed crystal.

The crystal growth results had the same tendency as the alexanthophyte single crystal growth in Example 1, and under normal temperature conditions ΔT =
Better crystals were obtained at 20° C., and a growth rate comparable to that at ΔT=2)° C. was obtained when the sintered density was around 85%.

Example 3 Kuemewold single crystal growth〉 Raw materials BgO41.2% AAzos 55.9% CrxOs 2.9% were mixed at a ratio of %I (111JIφ, sintered at a sintering density of 90mm, 10f was placed in a crucible, 5ho2 put the crystal in the second rib.

Flux is v205: LjzMgO4=1:
4002 was added at a ratio of 1 (%/l/ratio) and heated.

The growth conditions were 950°C for the base material, 945°C for the growing part, and 100°C for the growing part.
As the c1 seed crystal grown for 0 hours, natural beryl of 1 cyn square was used.

As a result, a constant growth rate of 0.03 yu/day was obtained, and no inclusions were observed except at the initial growth stage.

When a base material with a sintered density of 99.8 cm was used under the same temperature conditions, the crystal quality was the same, but the growth rate was 0.01 a.
The crystal growth rate was as slow as m+/day, and the difference in the sintered density of the base materials clearly appeared in the crystal growth rate.

As shown in the examples above, the present invention improves crystal quality by reducing the temperature difference between the crystal growth part and the base material, and reduces the growth rate by reducing the temperature difference between the base material and the base material. This could be compensated for by setting the sintered density to 60 to 99 inches.

According to the present invention, leather crystal synthesis technology using the flux method can easily improve quality and yield, so it can be used not only for functional crystals such as lasers but also for jewelry. Therefore, this invention is extremely useful in practice.

that's all Applicant: Suwa Seikosha Co., Ltd. Agent, Patent Attorney Rank, Senior Officer

Claims (1)

[Claims] In the method of synthesizing fluorescent crystals of oxides, fluorides, etc., which are different from the flux components by using oxides, fluorides, etc. as a flux, using the temperature difference method or slow cooling method, the raw material of the target M crystal component is sintered. A method for synthesizing a single crystal using a flux method, characterized in that the sintered density of the single crystal is increased from 60 inches to 99 inches.