JPH0416585A - Production of yellowish green rock crystal - Google Patents

Abstract

PURPOSE:To obtain the yellowish green rock crystal which is substantially free from unequal colors, is free from microcracks and has extremely good transparency by using CrO3 as an additive in a hydrothermal crystallization method. CONSTITUTION:CrO3 is added as an additive for coloring to the yellowish green rock crystal in the growth of the yellowish green rock crystal by the hydrothermal crystallization method. For example, a raw material 4 for growth and the CrO3 8 which is the additive for coloring are installed in the bottom of a pressure vessel body 1 subjected to pressure sealing with a cover 3 via a sealing ring 2. A seed crystal 6 is then disposed on the raw material 4 for growth via a seed crystal supporting frame 5 and a baffle plate 7 is installed via the frame 5 therebetween. The growth of the yellowish green rock crystal is thereafter executed. An aq. soln. of KOH is used as a solvent and is packed into the vessel 1 at such a packing rate at which the prescribed pressure is obtd. at a prescribed temp.

Description

[Detailed Description of the Invention] [Industrial Application Field 1] The present invention is a crystal of the same quality as amethyst (purple crystal), which is often used as an ornament, and is valuable as an ornament like amethyst. The present invention relates to a method for producing yellow-green artificial quartz.

E Summary of the Invention] The present invention provides a manufacturing method that can artificially synthesize yellow-green crystal, which is well known as a decorative item, at a predetermined temperature,
A yellow-green artificial quartz crystal is grown by adding Cr0= as a coloring additive using a hydrothermal synthesis method in which crystals are grown on seed crystals in an appropriate solvent under pressure.

[Prior Art 1] Conventionally, in the hydrothermal synthesis method, research and development on the growth of artificial crystals has been most active, and it can be said that this is the most successful example of crystal growth in the hydrothermal synthesis method. To date, mass production technology for most artificial quartz crystals has been established. Furthermore, research and development is being carried out on various colored crystals such as amethyst (amethyst) and other methods for producing colored crystals using this synthesis technology. Current colored crystals use potassium hydroxide (KOH) aqueous solution or potassium carbonate (K2CO,) aqueous solution as a solvent, temperature range 300~400℃, pressure 1000~1500 kg/
The cultivation is carried out under the conditions of "cm".

Moreover, various metal ions are used as one-color additives.

[Problems to be Solved by the Invention] In the conventional crystal growth of artificial quartz added with a coloring additive, although crystals can be grown, there are the following problems.

When using conventional coloring additives, there are problems with uneven coloring, such as darkly colored areas and lightly colored areas in the grown crystals, or insufficient coloring in the grown areas. There was a color problem. Further, there was also a problem of the generation of microcracks due to coloring.

[Means for solving the problem] Problems such as color tone, color unevenness, transparency, or the occurrence of microcracks in growing colored crystals using conventional hydrothermal synthesis methods are caused by the selection of coloring additives. .

There are various types of coloring additives, but CrOs is the most suitable coloring additive to solve the above problems.
I found out.

[Effect 1 In the hydrothermal synthesis method, starting materials are dissolved in an aqueous solution of an appropriate solvent at an appropriate temperature and pressure, and crystals are grown into seeds by slow cooling or by transporting nutrients using the temperature difference. Grow on crystals. A coloring additive is added during this crystal growth. As a result, the coloring additive becomes a metal ion in the aqueous solution and is incorporated into the crystal. Crow was used as the coloring additive. CrOs is an ideal additive when growing yellow-green artificial quartz.

Hereinafter, a detailed explanation will be given according to examples.

〔Example〕

FIG. 1 shows a cross-sectional view schematically showing the configuration of this embodiment.
The pressure vessel body 1 is pressure-sealed by a cover 3 via a seal ring 2 and has a configuration of 0 or more, in which a growth raw material 4 and a coloring additive Cr0s8 are installed at the bottom of the pressure vessel body. As the raw material 4 for growth, a seed crystal 6 is prepared by crushing a natural quartz crystal (lath force) into an appropriate size.
Natural or artificial crystals are used as the seed crystals 5 which are placed on the growing material 4.

There are various crystal planes of the seed crystal (for example, two planes, Y plane,
A type with two sides (R side, etc.) is used, but this time I used one with two sides. In addition, a seed crystal with particularly few internal inclusions and dislocations is required so as not to cause defects in the single crystal to be grown. The growing raw material 4 and the seed crystal 6 are arranged in this manner, and a baffle 1fii7 is also installed between them via the seed crystal support frame 5. Yellow-green quartz was grown in a pressure vessel with such a configuration. A KOH aqueous solution was used as the solvent and filled into the pressure vessel at a filling rate such that a predetermined pressure was obtained at a predetermined concentration.

Hydrothermal synthesis was performed with the above settings. That is, as follows.

Example 1 Temperature of seed crystal 6...320°C Temperature of growing raw material 4...340°C Solvent...1.0 mol KOH aqueous solution Coloring additive amount...Cr0a0.5% by weight Pressure--・
1000 kg/cs+'' Growth period: 10 days As a result, yellow-green crystals as shown below were grown on one seed crystal 6.

Thickness of the grown layer: 6.1 mm Growth rate: 610 um/day Properties of the grown layer: α-quartz (fixed by X-ray diffraction), very few defects such as inclusions and cracks Crystals with uniform color were obtained.

Example 2 Temperature of seed crystal 6: 340°C Temperature of growing raw material 4: 360°C Solvent: 1.0 mol KOH aqueous solution Coloring additive amount: Crys 0.5% by weight Pressure・
- 1000 kg/c112 Growth period: As a result of 10 days, the following yellow-green crystals were grown on the seed crystal 6.

Thickness of the grown layer: 7.5 mm Growth rate: 750 μm/day Properties of the grown layer: α-quartz (fixed by X-ray diffraction), very free of defects such as inclusions and cracks Crystals with little color unevenness were obtained.

Example 3 Temperature of seed crystal 6: 320°C Temperature of growing material f44: 340°C Solvent: 1.0 mol KOH aqueous solution Amount of coloring additive: Cr0a l. 0 weight% pressure...
-1000kg7cm2 Growth period: 10 days As a result, yellow-green crystals as shown below were grown on the seed crystal 6.

Thickness of grown layer: 5.9 mm Growth rate: 590 μm/day Properties of grown layer: α-quartz (fixed by X-ray diffraction method), very few defects such as inclusions and cracks Crystals with uniform color were obtained. Furthermore, compared to the yellow-green crystal grown in Example 1, a yellow-green crystal with a slightly deeper color was grown.

[Effects of the Invention] As detailed above, according to the present invention, by using CrO2 as a coloring additive, it is possible to grow yellow-green quartz with almost no color unevenness and very good transparency.

Furthermore, it becomes possible to grow yellow-green crystals that have sufficient value as ornaments, and the effect is extremely large.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a pressure vessel. pressure vessel body Seal ring hippopotamus Raw materials for growing Seed crystal support frame seed crystal baffle plate Additive for coloring

Claims (1)

[Claims] A method for producing yellow-green crystal, characterized in that yellow-green artificial crystal is grown by adding CrO_3 as a coloring additive in a hydrothermal synthesis method in which crystals are grown by applying a predetermined temperature and pressure.