JPH02307883A - Production of aquamarine single crystal - Google Patents

Abstract

PURPOSE:To produce the high-quality product having less internal strains at a low temp. by growing the aquamarine single crystal by a hydrothermal crystallization method using an aq. NaNO3 soln. as a solvent. CONSTITUTION:Raw materials 4 for growing and a coloring material 8 are installed in the bottom of a pressure vessel body 1 which is sealed of pressure by a cover 3 via a seal ring 2. The raw materials 4 which are synthesized by a flux method or are formed by grinding and pulverizing natural beryl crystals are used. A seed crystal 6 is then disposed above the raw materials 4 and the coloring material 8 via a supporting frame 5. While a planar crystal cut at 45 deg. angle from the less defective C-axis of the natural beryl crystals is used as the seed crystal 6, artificial beryl crystals are equally satisfactory and the cutting angle may be other angles as well. A baffle plate 7 is provided between the raw materials 4 and the seed crystal 6 and the aq. NaNO3 soln. is packed as the medium into the body 1 at such a packing rate at which a prescribed pressure is obtd. at a prescribed temp. The hydrothermal crystallization is then executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing aquamarine single crystals, which are widely used as decorative jewelry.

[Summary of the invention]

The present invention is an aquamarine single crystal that can grow aquamarine single crystals of quality that can be used for decoration by a hydrothermal synthesis method in which crystals are grown on seed crystals using NaJO as a solvent and an aqueous solution at a predetermined temperature and pressure. A manufacturing method is provided.

[Conventional technology]

Traditionally, natural aquamarine has been used as a decorative item. However, there were many crystals with impurity inclusions or microcranks, and there were very few large crystals of good quality.

Furthermore, hydrothermal synthesis has traditionally been the most active area of research and development for growing artificial crystals, and can be said to be the most successful example of crystal growth using hydrothermal synthesis. To date, mass production technology has been established for most of the artificial quartz crystals. However, for crystals other than artificial quartz, mass production technology has not been established to date.

[Problem to be solved by the invention]

Regarding the conventional technology, the flux method, the problem is that there are many defects inside the single crystal, especially includicine. In the case of the flux method, since a single crystal is synthesized from molten flux at a high temperature of around 1000° C., the flux is mixed in and becomes internal defects in the crystal as inclusions. This is an unavoidable drawback of the flux method. On the other hand, compared to the flux method, in the hydrothermal synthesis method, the solvent is a low-viscosity aqueous solution, and the synthesis temperature is around 500℃, which reduces the occurrence of inclusions or internal distortion due to heat, resulting in high-quality aqua with fewer defects. This is a method that can produce marine single crystals.

[Means for Solving the Problems] In order to bring the production of aquamarine single crystals by hydrothermal synthesis closer to an industrial level, it is important to first select the solvent (solvent). this? Yong? The conditions for fl are aquamarine single crystal BeJ j! z(SiO*)a(
It has a certain degree of solubility in Fe ion dope), the aquamarine single crystal exists stably in this solution (at high temperature and high pressure), and it is less corrosive to pressure vessels.

In the present invention, NaNO
It has been found that an aqueous solution of 3 is optimal as a solvent.

[Effect]

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 temperature difference is used to transport nutrients by convection to crystallize or Grow on a suitable substrate. As mentioned above, an aqueous NaJO solution is an ideal container for growing such aquamarine single crystals.

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 is a Stellite 25 autoclave. The pressure vessel main body 1 is pressure-sealed by a cover 7 via a seal ring 2.

In the autoclave having the above configuration, the raw material for growth 4 and the coloring material 8 are placed at the bottom of the pressure vessel. As the raw material 4 for growth, beryl crystals synthesized by a flux method or natural beryl crystals pulverized into powder are used. Next, a seed crystal 6 is placed on the growth raw material 4 and the coloring material 8 via a seed crystal support frame 5 . As a seed crystal, choose a natural beryl crystal with few defects.4 from the C axis.
A plate cut at an angle of 5° was used. however,
The seed crystal may be an artificial beryl crystal.

Further, although there are differences in the growth rate regarding the cutting angle, seed crystals cut at other angles may be used. This seed crystal is pretreated by etching as necessary. Arranging the growth raw material 4 and the seed crystal 6 in this way,
In between, a baffle plate 7 is installed with a seed crystal support frame 5 interposed therebetween. This baffle plate is installed for the purpose of convection control and temperature control inside the pressure vessel. The pressure vessel having such a structure is filled with a NazNO3 aqueous solution as a medium at a filling rate such that a predetermined pressure is obtained at a predetermined temperature.

Aquamarine single crystals were grown with the above settings. It is as follows.

(Example a) Temperature of seed crystal 6---390°C Temperature of growth raw material 4 -420°C Solvent----3 mol NaJOs aqueous solution colorant---
-------~-FeCOH)s 114℃% pressure---
--800 kg/cd growing period---1---
- As a result of growing under the above conditions for 10E1, an aquamarine single crystal was grown on the seed crystal 6. The results and properties are shown below.

Thickness of grown layer --- 1, 2 s -- Growth rate -- Knee 1 --- 11 --- 120 μl/
Properties of day-grown layer---Aquamarine single crystal (XvA
A highly complete single crystal with very few microcracks and inclusions (identified by diffraction) was obtained.

(Example b) Temperature of seed crystal 6 -------=370°C Temperature of growing raw material 4 ----400°C Solvent ----1------
----3 mol NaJO3 water i8? (1 coloring material"""
”−””−”−−−−Fe ((Iff) 31 w
t'3/.

Pressure'-----800Jy/cn! Cultivation period...------------1-----1
As a result of growing under the above conditions for 0 days, an aquamarine single crystal was grown on the seed crystal 6. The results and properties are shown below.

Thickness of grown stone -1111・1.05mm Growth rate---1---------------・105 Immediately/day Property of layer grown t=- --- Aquamarine single crystals (identified by X-ray diffraction) Microcrank and very little integrity single crystals of inclusidine were obtained.

〔Effect of the invention〕

As detailed above, according to the present invention, by using a hydrothermal synthesis method and using an aqueous NazNOz solution as a solvent,
Compared to natural aquamarine single crystals, it is possible to obtain highly complete aquamarine single crystals with very few inclusions and microcracks.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a pressure vessel used in the present invention. 1...Pressure vessel body 2...Seal ring 3...Cover 4...Raw material for growth 5...Seed crystal support frame 6...Seed crystal 7...Baffle plate 8...Coloring More than wood

Claims (1)

[Claims] A method for producing an aquamarine single crystal, characterized in that the aquamarine single crystal is grown by a hydrothermal synthesis method in which a predetermined temperature and pressure are applied in an Na_2NO_3 aqueous solution.