JPH0416584A - Production of greenish brown rock crystal - Google Patents

Abstract

PURPOSE:To obtain the greenish brown rock crystal which is substantially free from unequal colors, is free from microcracks and has extremely good transparency by using Pb3O4 as an additive in a hydrothermal crystallization method. CONSTITUTION:Pb3O4 is added as an additive for coloring to the greenish brown rock crystal in the growth of the greenish brown rock crystal by the hydrothermal crystallization method. For example, a raw material 4 for growth and the Pb3O4 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 greenish brown 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] The present invention is often used as a decorative item. This article concerns a method for manufacturing a greenish-brown artificial crystal, which is of the same quality as amethyst and is valuable as an ornament, just like amethyst. [Summary of the Invention] The present invention is a manufacturing method that can artificially synthesize colored crystals, which are well known as decorative items, in which crystals are grown on seed crystals in an appropriate solvent by applying a predetermined temperature and pressure. A hydrothermal synthesis method is used to grow greenish-brown artificial quartz crystals by adding PB and O as coloring additives. [Prior Art] Conventionally, in the hydrothermal synthesis method, research and development on growing artificial quartz 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 conducted on various colored crystals such as amethyst as well as methods for producing colored crystals using this technology. Current colored crystals are produced using an aqueous solution of potassium hydroxide (KOH) or potassium carbonate (
KxCO3) aqueous solution, temperature range 300-400
℃ and a pressure of 1000 to 1500 kg/ca+''. Various metal ions are used as coloring additives. [Problems to be solved by the invention] Conventional coloring additives When growing artificial quartz crystals using additives, although crystals can be grown, there are the following problems: When conventional coloring additives are used, darkly colored areas may appear in the grown crystals. There were problems with color unevenness, such as the formation of lightly colored areas, and problems with color tone, such as insufficient coloring of the growing areas.Additionally, there were also problems such as the generation of microcracks due to the coloring.

[Means for solving the problem] Problems such as color unevenness, transparency, or 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. P as the optimal coloring additive to solve the above problems
We found b5O4. 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 the crystals are seeded 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. PbaO was used as the coloring additive. PbxO4 is an ideal additive when growing blue artificial quartz. [Example] FIG. 1 shows a cross-sectional view schematically showing the configuration of this example.
The pressure vessel body 1 is pressure-sealed by a cover 3 via a seal ring 2. In a pressure vessel having a configuration of 0 or more, a growth raw material 4 and a coloring additive of Pbs 0.8 are installed at the bottom of the pressure vessel body. 3 As the raw material 4 for growth, a natural crystal rough stone (lath force) crushed into an appropriate size is used.Next, the seed crystal 6 is placed on the raw material 4 for growth via the seed crystal support frame 5. 0 seed crystals placed in 5
Various types of crystal planes (e.g., 2-sided, Y-plane, R-plane, etc.) are used as crystal planes for zero-seed crystals using natural or artificial crystals, but this time we will use 2-sided crystals. used. 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 way, and the seed crystal support frame 5 is placed between them.
A baffle plate 7 is installed via. Greenish-brown quartz crystals were 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 could be obtained at a predetermined temperature. 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: 0.5 mol KOH aqueous solution Coloring additive amount: pbs O, 1.0% by weight pressure·
...1000 kg/c■8 Growth period...10 days As a result, greenish brown crystals as shown below were grown on the seed crystal 6. Thickness of grown layer: 6.5+wm Growth rate: 650 μm/day Properties of grown layer: a-crystal (fixed by X-ray diffraction method), 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: 0.5 mol KOH aqueous solution Coloring additive amount: Pba O, 1.0% by weight pressure·
-・1000kg/c+w'' Growth period: 10 days As a result, greenish brown crystals as shown below were grown on the seed crystal 6. Thickness of the grown layer: 70-m Growth rate:・Properties of layer grown at 700 μm/day: α-quartz (fixed by Xl11 diffraction method), uniform color crystals with very few defects such as inclusions and cracks were obtained. Example 3 Seed crystals Temperature of 6: 320°C Temperature of growing raw material 4: 340°C Solvent: 0.5 mol KOH aqueous solution Coloring additive amount: Pbz 040.5% by weight Pressure
...1000 kg/cI112 Growth period...10 days As a result, greenish brown crystals as shown below were grown on the seed crystal 6. Thickness of the grown layer: 6.7 mm Growth rate: 670 μm/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. [Effects of the Invention] As detailed above, according to the present invention, by using PB and O as coloring additives, it is possible to grow greenish-brown crystals with almost no color unevenness and very good transparency. be. In addition, it becomes possible to grow greenish-brown crystals that have sufficient value as ornaments, and the effect is extremely large. 4,

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a pressure vessel. Pressure vessel body ·Seal ring ·cover ・Raw materials for growth ・Seed crystal support frame ・Seed crystal ・Baffle plate ・Additive for coloring Applicant: Seiko Electronics Industries Co., Ltd.

Claims (1)

[Claims] A method for producing green-brown quartz, characterized in that green-brown artificial quartz is grown by adding Pb_3O_4 as a coloring additive in a hydrothermal synthesis method in which crystals are grown by applying a predetermined temperature and pressure.