JPH0328400B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing a spodium single crystal.

[Prior art]

The crystal of spodiumen belongs to the monoclinic system, and its chemical composition is Li ₂ O.Al ₂ O _{3.4SiO 2} . There are many types of crystal colors: colorless, gray, yellow, pink,
The most commonly known colors are purple, pale green, green, greenish-yellow, blue-green, and blue. In general, those with a greenish color are called hiddenite, and those with pink to purple colors are natural gemstones called kunzite (Gemstones - Their Beauty and Science - pp. 283-285, National Gemological Association, Gemstone Enhancement Page 162
But terwoths, Encyclopedia of Chemistry 9 1964 No. 606
(See page Kyoritsu Publishing Co., Ltd.).

So far, there has been no report on the production of spodiumen single crystals. This is because spodiumen is stable in the β form at high temperatures and in the α form at low temperatures.
This is because it will break when brought from a temperature above (above) to a low temperature (room temperature).

[Purpose of the invention]

An object of the present invention is to provide an inexpensive and easy method for producing a spodumene single crystal.

[Summary of the invention]

In the present invention, 1 mol each of powders of lithium oxide, alumina oxide, and silicon oxide is mixed with metals (Ni, Ti, Fe, Cr, Mn, Cu, etc.) or oxides (NiO, TiO ₂ , Ti _{2 )} as additives. _O3 , FeO, _Fe2O3 , _{MnO2 ,}
0.001 to 0.005 mol of VO ₂ , CuO, etc.) is added and mixed to produce a sposiumene single crystal by a unidirectional solidification method using the mixture as a raw material. As the unidirectional solidification method, there are a floating zone method, a pulling method, a Bridgeman method, and a slow cooling method with a temperature gradient, and the floating zone method is particularly suitable. This is because the floating zone method (hereinafter abbreviated as FZ method) does not require a crucible, so no force is applied from the crucible during phase transformation, and the temperature gradient can be easily adjusted. Figure 1 shows an outline of the FZ method. 1 is a raw material, 2 is a high-frequency coil, 3 is a heat insulating material, 4 is a crystal, 5 is a heater, and 6 is a melt.
That is, the mixed raw materials are rubber pressed, then sintered,
As shown in FIG. 1, the raw material is placed at 1 and the seed crystal is placed at 4. The raw material and seed crystal are melted using a heater and a high-frequency coil, and the crystal is grown. At this time, the temperature gradient of the crystal is controlled by controlling the power of the heater. This seed is shown in FIG.

The horizontal axis represents the position, and the vertical axis represents the temperature. 1 is the crystallization starting point, and 2 is the transformation point. That is, the temperature gradient before transformation is 4 to 10℃/cm, and that after transformation is 0.5 to 4℃/cm.
cm, it is possible to prevent cracking due to phase transformation.

In the present invention, the reason for the numerical limitation is as follows:
This is because if the amount is less than 0.001 mol, the color tone of the single crystal will not be sufficient, and if it exceeds 0.05 mol, the color tone of the single crystal will become dark.

Hereinafter, the remarkable effects of the present invention will be shown according to Examples.

Example 1 1 mole each of lithium oxide, alumina oxide, and silicon oxide powder, and 0.001 to 0.05 of chromium oxide
Add mol, especially 0.01 mol, mix and form a sintered bar. This was placed in an FZ furnace together with a seed crystal, and a single crystal was grown. At this time, a green spodiumen (hiddenite) single crystal was grown at a crystal growth rate of 1 to 3 mm/hr and a crystal diameter of 3 to 8 mm.

Example 2 A sintered rod was made in the same manner as in Example 1, except that the oxides were 0.005 to 0.05 mol of titanium oxide (TiO ₂ ), 0.005 to 0.05 mol of iron oxide (FeO), and especially 0.01 mol of titanium oxide.
mol, 0.02 mol of iron oxide is good, and this was installed in an FZ furnace to grow a sposimen single crystal. Crystal growth rate 2-5mm/hr, crystal diameter 3-8
We were able to grow a sposiumene single crystal with a light blue color in mm.

In this example, only oxides were used as additives, but even metals themselves are sufficiently oxidized and converted into oxides during the process of forming raw material rods and growing single crystals, so there are no additives. No problem.

In addition, by combining elements such as Ni, Mn, Cu, and V as additives, sposimen of various colors can be obtained.

〔Effect of the invention〕

The effects of the present invention are that by controlling the temperature gradient using a unidirectional solidification method, cracking caused by phase transformation can be solved, and spodumene single crystals of various colors can now be produced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the FZ method, where 1 is a raw material, 2 is a high-frequency coil, 3 is a heat insulator, 4 is a crystal, 5 is a heater, and 6 is a melt. FIG. 2 is a diagram relating to the position and temperature of the crystal, where the horizontal axis is the position and the vertical axis is the temperature, where 1 is the crystallization starting point and 2 is the transformation point.

Claims (1)

[Claims] 1 Lithium oxide (Li ₂ O), alumina oxide (Al ₂ O ₃ ), and silicon oxide (SiO ₂ ), which have approximately the same composition ratio as spodumene, and metals (Ni, Ni,
Ti, Fe, Cr, Mn, V, Cu ₎ or oxides (NiO, _TiO2 , _Ti2O3 , _{Fe2O3 , MnO2} , VO2 _,
A method for producing a sposiumene single crystal, which is characterized in that 0.001 to 0.05 mol of CuO) is added and mixed as a raw material, and the mixture is crystallized by a unidirectional solidification method.