JPS5938195B2 - Production method of brilliant chrysoberine single crystal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a brilliant chrysoberyl single crystal.

Conventionally, chrysoberyl single crystals have been produced by the flux method and the floating zone method.

The flux method has the disadvantage that the resulting crystals tend to form twins, making it difficult to obtain large single crystals.

Furthermore, the floating zone method was unsuccessful because it was difficult to dissolve the TiO2 component, which causes the shine, into a solid solution.

The brilliant chrysoberyl single crystal, commonly known as cat's eye, is produced by TiO2 contained as an impurity in the chrysoberyl mother crystal, which is precipitated in a specific direction by dissolution, which causes a light diffraction effect. It is something that shines.

Therefore, in order to produce a brilliant chrysoberyl single crystal, it is first necessary to produce a chrysoheryl solid solution single crystal in which the TiO2 component is homogeneously dissolved.

However, since the conventional floating zone method uses air as the atmosphere, the amount of solid solution of the TiO□ component in chrysoberyl is at most 0.5 mol or less, and this amount of solid solution does not have a sufficient effect of producing brilliance. , and 0.
Even if more than 5 mol of TiO□ component is added, the maximum amount of solid solution is less than 0.5 mol,
The two components rarely had the disadvantage of being dispersed in the crystal and becoming opaque.

The object of the present invention is to provide a method for producing a brilliant chrysoberyl single crystal by increasing the amount of TiO2 component dissolved in the solid solution and uniformly dissolving the TiO2 component in the solid solution using the floating zone method.

As a result of research to achieve the above object, the present inventor found that the amount of solid solution of TiO2 component in chrysoberyl changes depending on the oxygen partial pressure of the single crystal growth atmosphere, and when the oxygen partial pressure becomes low, TiO2
A new finding was obtained that the amount of solid solution of two components increases.

In other words, the amount of solid solution was less than 0.5 mol in an air atmosphere, but when the partial pressure of oxygen in the atmosphere became 10-1 atm, the amount of solid solution increased, and the maximum amount of solid solution was 3 mol. %.

Furthermore, it has been found that when the growing atmosphere in the floating zone method is a reducing atmosphere, particularly a reducing atmosphere of 10<-1>atm or less, the TiO2 component can be easily dissolved as a solid solution.

In addition, in order to grow a single crystal in which the TiO2 component is uniformly dissolved in solid solution, it is necessary to melt the sample by moving it in a melting zone that allows the growth to continue without changing the precipitation temperature of the solid phase. The traveling zone method, which allows solid phase precipitation to continue, is suitable, and when the obtained single crystal is annealed in an oxidizing atmosphere, the TiO□ component dissolutes and precipitates to easily form brilliant chrysoberyl crystals. We have determined what can be obtained.

The present invention was completed based on this finding.

The present invention uses beryllium oxide (Bed) as the raw material rod in a single crystal growth method using a floating zone method in which one end of the raw material rod is melted and the formed melt zone is moved to continue melting of the raw material rod and precipitation of the solid phase. ), a chrysoberyl single crystal component made of aluminum oxide (At203) and a titanium dioxide (TiO□) component are used, and a reducing atmosphere with an oxygen partial pressure of 10-1 atm or less is used as the growth atmosphere. The gist is a method of growing a single crystal and annealing the obtained single crystal in an oxidizing atmosphere to precipitate the TiO2 component.

In the floating zone method used in the present invention, for example, a raw material rod is set above and a seed crystal is set below, a molten zone of solvent is formed between the two, and this is held by surface tension.

Next, when the molten zone is slowly moved upward, melt penetration of the raw material rod occurs above the molten zone, and crystal precipitation occurs below the molten zone.

At this time, the raw material rod and the seed crystal are rotated in opposite directions at appropriate speeds to give a stirring effect to the molten zone.

In this way, the molten zone is used as an intermediary to connect the materials, and the molten zone is slowly moved with no support other than the raw material rod and the seed crystal to grow a single crystal.

Raw material rods include beryllium oxide (Bed), aluminum oxide (At203), and titanium dioxide (Ti
O2) component ratio is approximately 1:1:0.0005 in molar ratio
It is preferable that the ratio is 1:1:0.05.

Chrysoberyl crystals are represented by the chemical formula BeAt204, and are a compound in which BeO and At203 have a molar ratio of 1:1, and the ratio of both is approximately 1:1 in molar ratio.

If titanium dioxide is less than the above ratio, the brilliance will be less than 50%, and if it is more than the above ratio, the whole will be cloudy and not beautiful.

The solvent was beryllium oxide (Bed), aluminum oxide (
The component ratio of At203) and titanium dioxide (TiO2) is approximately 1:1:0.001 to 1:i:o in molar ratio.
, i, whose melting point is lower than the melting point of the raw material rod.

As the TiO2 component increases, its melting point decreases, so the amount of TiO2 in the solvent may be adjusted depending on the composition of the raw material rod.

Although it is possible to precipitate a single crystal without using a solvent, if it is not used, the composition of the initially formed crystal will deviate from the intended one, resulting in poor retention.

Moreover, if there is no seed crystal, polycrystals will initially be produced, which has the disadvantage of being wasted.

Aluminum oxide, beryllium oxide, and titanium dioxide, which are the raw materials for the raw material rod and the solvent, can be used as they are at ordinary reagent grade, but in order to allow the mutual chemical reaction to proceed quickly, granular The smaller the diameter is, the more preferable it is, and the diameter is preferably 1 mm or less, particularly 10 μm or less.

It is necessary to mix these raw materials as uniformly as possible.

For this purpose, it may be sufficiently mixed with an organic reagent such as an alcohol or acetone in a mortar, or by using a ball mill or the like.

In this case, if necessary, Fe, Mg, Ca.

Ba, V, Crp Mn, Co, Ni,
Cu, Zn.

Colorability, processability, etc. can be changed by adding a trace amount of Ge or a rare earth element.

These mixed raw material powders are press-molded.

For pressure forming, a molding method using one or two directions of compression using a mold may be used, but in order to prevent bending during heating, a rubber press method in which pressure is applied isotropically may be used. preferable.

The rubber press method is a method in which raw material powder is placed in a rubber tube, both ends of which are sealed, and the tube is pressurized with high hydraulic pressure in a closed hydraulic pressure vessel.

The liquid pressure is 500 kg/:rl, any pressure can be used as long as it is higher than that, but 1 to 2 tons is cheap and easy to obtain.
/ci is preferred.

The pressurization time is 5 seconds or more, preferably 1 minute.

Molded products that are not sufficiently pressurized are likely to break.

The shape of the pressure-molded product may be long and thin, but a cylindrical shape is preferred.

Its size is, for example, a diameter of 1rI1m to 10crn, a length of IWtm to 50c, and preferably a diameter of 3Wtm to 3cfn.
, the length is 5111n to 30cm.

The press-molded product is calcined.

This calcination may be heated by holding it in a crucible in a horizontal furnace, but in order to prevent contamination of impurities and bending during calcination,
It is preferable to heat the product in a suspended state in a vertical furnace.

The heating temperature of the press-molded product is 1400-1 in the case of raw material rods.
750°C, preferably 1300 to 1500°C in the case of a solvent.

The longer the heating time, the better.

In particular, in the case of a raw material rod, it is preferable to heat it for a sufficiently long time so that the bulk density after sintering reaches a factor of 80 or higher.

The solvent is preferably fused under the raw material rod or on top of the seed crystal.

The amount of solvent is most preferably a hemisphere having the same diameter as the raw material rod.

The seed crystal may be any solid material that can withstand high temperatures and does not cause a chemical reaction with the solvent, but it is preferable to use the same material as the raw material rod, especially a chrysoberyl single crystal.

To melt the solvent by the floating zone method, for example, a condensing heating method in which light from a high-temperature light source is condensed using a mirror or lens is used to heat the solvent to a temperature above the melting temperature over a range of 3 to 30 WtrIL in the upper and lower directions.

The crystal growth rate is equal to the downward feeding rate of the raw material rod and the seed crystal, and the feeding rate is at least Q, l mm per hour.
It is preferable to keep it at

A particularly preferred speed is 1 to 10 mm per hour.

The atmosphere for this crystal growth must be a reducing atmosphere with an oxygen partial pressure of 10<-1> or less.

Solid solution of cresoberyl single crystal of TiO2 is 2Ti02→T
Since Ti2O3 produced by the reduction reaction of i2O3+'/, 0□ is dissolved in solid solution, if the oxygen partial pressure is large, the above reaction will not proceed and it will not be possible to form a solid solution.

For example, a mixed gas containing CO2 and hydrogen in a ratio of 1=5 and nitrogen and hydrogen in a ratio of 10:1 can be cited.

When the obtained single crystal is annealed in an oxidizing atmosphere having an oxygen partial pressure of 0.1 atm or more, the TiO□ component precipitates by dissolution and becomes shiny.

In addition, if a single crystallized raw material rod is used instead of the sintered raw material rod described above, the raw material will be evenly dissolved into the solvent, and therefore crystallization on the seed crystal will be stable. High quality products can be obtained.

As described above, according to the method of the present invention, by creating a reducing atmosphere, it is possible to easily obtain a homogeneous solid solution of TiO2 component in chrysoberyl. Furthermore, by annealing the obtained single crystal in an oxidizing atmosphere, it has the excellent effect of obtaining a cresoberyl single crystal that emits a beautiful glow.

Example 1 Pure [99.9% or more aluminum oxide (At203)]
Powder and Bed oxide) IJum (Bed) powder and purity 9
9.9% or more titanium dioxide (TiO2) powder and 100:100:0.1 for chrysoberyl raw material.
5. Weighed the solvent raw materials at a ratio of 100:100:0.3, and used the commercially available special reagents cobal oxide (Cod) and chromium ditrioxide (Cr20) as coloring agents for each raw material.
3) were added in a molar ratio of 0.1% and 0.2%, respectively,
Ethyl alcohol was added and thoroughly mixed in a mortar to obtain a mixture of two types of fine powder with an average particle size of 1 μm.

The two kinds of mixtures 121 were put into thin rubber tubes with an inner diameter of 11 mm, and both were sealed.
Insert it into the metal frame of ff, and put it in the hydraulic hydrostatic pressure generator.
It was pressed and molded at a pressure of ton/lvt for about 1 minute.

Outer diameter of about 9 mm and length of about 80 mm obtained by the above operation
In the case of chrysoberyl raw material, heat the round bar sample to 1600℃.
In the case of solvent raw materials, they were inserted into a vertical electric furnace maintained at 1500° C. and calcined.

Inserting the sample into the furnace and removing it from the furnace took 1 hour each to prevent destruction of the sample due to rapid heating and cooling.

The atmosphere was airy.

Outer diameter of about 7.5mm and length of about 70W obtained by the above operation
t7+! A raw material rod of chrysoberyl was fixed to the upper sample rotating shaft of a floating zone method single crystal production device that adopted an infrared concentrated heating method, and an outer diameter of approximately 8 mm was obtained in the same manner.
Cut the solvent stick into a length of about 2Qmm.

A 10:1 mixed gas of nitrogen and hydrogen was introduced as an atmosphere into the crystal growth chamber, which was fixed to the lower seed crystal rotating shaft of the above apparatus and isolated from the outside air by a fused silica tube, and heating was started.

The atmosphere is at a linear velocity of 0.0 per second near the floating zone.
6 cm.

Adjust the tip of the solvent rod so that it is located at the highest temperature point in the single crystal manufacturing apparatus, and at the same time as the tip melts due to heating, the heating is kept constant to fix the temperature.

The chrysoberyl raw material rod was moved downward from the upper side and combined with the solvent rod through the molten part, and both frames were rotated in opposite directions at a speed of 50 revolutions per minute.

Rotation was continued until the end of crystal growth.

After finely adjusting the temperature and the spacing between the two frames to obtain a state in which the molten area is neither too large nor too small, both frames are moved downward at the same speed at 2.5 hours per hour. It was moved at a speed of Q mm to precipitate hechrysoberyl crystals on the solvent bar.

The precipitated crystals were initially polycrystalline, but 10~30rln
After growth, it had a single crystal cross section.

When the chrysoberyl raw material rod was almost completely consumed, the grown single crystal and the raw material rod were separated and cooled to a diameter of 6.5 m.
A round rod-shaped chrysoberyl single crystal with a length of 45 mm was obtained.

This single crystal was inserted into a vertical electric furnace maintained at 1350° C. and annealed in an oxygen atmosphere of 1 atm for 48 hours.

Insertion into the furnace and withdrawal from the furnace took one hour each to prevent deterioration of crystal quality and destruction of the sample due to rapid heating and cooling.

After cutting the single crystal subjected to the above operation, it was polished to obtain a cabochon type quarried stone.

The quarry showed clear glow under single light.

Tie in the produced crystals. The amount of component solid solution is TiO2 in the raw material.
It was found to be less than 1.5 moles, which is the same as the component amount.

By increasing the amount of TiO2, the amount of the TiO2 component dissolved in chrysoberyl can be made up to 3 mol%.

Comparative Example 1 The experiment was conducted under the same conditions as in Example 1 except that the atmosphere gas was air, which is commonly used.

TiO2 was not homogeneously dissolved in the crystal, and only cloudy crystals were obtained.

The solid solution amount of Tie2 was determined to be 0.5 molar or less.

Example 2 Using the single crystal obtained by the crystal growth method of Example 1 as a raw material, recrystallization was performed in the same manner as in the crystal growth method of Example 1 to obtain a high quality product with a diameter of 5.5 mm and a length of 45 mm. A chrysoberyl raw material rod was obtained.

This single crystal was annealed in the same manner as in Example 1, then cut, and the cut pieces were polished to obtain a capochon type quarried stone.

The quarry showed clear glow under single light.

Further, the cut surface was treated with potassium hydrogen sulfate (KH8O,) at 670° C. for 1 minute, and the presence of foreign phases and phagocytic bacteria was observed using a microscope.

As a result, the presence of different phases was not observed in this single crystal, and
It was confirmed that the density of phagocytic bacteria thought to be caused by translocation was also less than 1,000 per 17 cells.

Claims (1)

[Claims] 1. In a single crystal growth method using a floating zone method in which one end of a raw material rod is placed in a melting bag and the formed melt zone is moved to continue melting of the raw material rod and precipitation of a solid phase, the raw material rod is used as a single crystal growth method. Beryllium oxide (Bed), aluminum oxide (At
203) and titanium dioxide (T i 02 ), a single crystal is grown using a reducing atmosphere with an oxygen partial pressure of 10 −1 atm or less as a single crystal growth atmosphere. A method for producing a brilliant chrysoberyl single crystal, which is characterized by annealing a single crystal in an oxidizing atmosphere to precipitate a TiO2 component. 2 The floating zone method places the solvent under the raw material rod,
2. The method according to claim 1, wherein a seed crystal is further provided under the solvent, and the solvent portion is heated to dissolve the solvent and the melting zone is moved. 3 The raw material rods are oxidized aluminum (BeO), aluminum oxide (AA2 o3) and titanium dioxide (
The molar ratio of the components of TiO2) is 1:1:0.0005~
A method according to claim 1 comprising a ratio of 1:1:0.05. 4 In a single crystal growth method using the floating zone method in which one end of the raw material rod is melted and moved through the formed melt zone to continue melting of the raw material rod and precipitation of the solid phase, beryllium oxide (BeO), oxide, etc. are used as the raw material rod. Aluminum (At
20 s) and titanium dioxide (TiO2), a single crystal was grown using a reducing atmosphere with an oxygen partial pressure of 10-1 atm or less as a single crystal growth atmosphere. Production of a brilliant chrysoberyl single crystal characterized by repeating the growth of a similar single crystal using a single crystal as a raw material rod and annealing the obtained single crystal in an oxidizing atmosphere to precipitate a TiO2 component. Law.