JPS6265999A - Production of prussian blue forsterite single crystal - Google Patents

Abstract

PURPOSE:To easily and inexpensively produce a Prussian blue forsterite single crystal by forming a melt zone to one end of a bar-shaped raw material which consists of MgO, SiO2 and Cr2O3 and is sintered and depositing a solid phase at the solid-liquid boundary of the melt zone, thereby executing crystallization. CONSTITUTION:The melt zone 8 is formed by using a halogen lamp 2, etc. to one end of the sintered bar-shaped raw material 3 consisting of the three components; 40-80mol% MgO, 20-50% SiO2 and 0.01-10% Cr2O3 within a mirror body 1 of ellipsoidal surface of revolution. While the melt zone 8 is moved, the melting of the raw material is executed at one of the solid-liquid boundaries thereof and the solid phase is deposited at the other solid-liquid boundaries. The solid phase is crystallized on a seed crystal 5 fixed to the top end of a lower revolving shaft 6. A radiation preventive tube or/and after heater 9 are preferably provided to enclose the lower part of the zone 8 and near the same to horizontally maintain the solid-liquid boundary for making the deposition and crystallization of the above-mentioned solid phase.

Description

[Detailed description of the invention] [Industrial application field] Forsterite is a type of olivine, and Mg28i
It is known by its chemical formula 04. Olivine usually has yellow, greenish-yellow, dark olive colors, etc. In particular, yellow-green stone is called olivine, and olive-green stone is called beridot, and has been prized as a decoration for jewelry and the like since ancient times.

Also, due to its physical properties, it is expected to be used as electronic and optical materials.

The present invention relates to a method for producing a dark blue forsterite single crystal containing chromium ions.

[Conventional technology]

Conventionally, attempts to grow forsterite single crystals using the flux method, Bridgman method, pulling method, etc. have been reported. Forsterite solid solution doped with transition metal ions, Finoh et al.
There is a report that a crystal with ``,Or''Oyo0'Fe'''kl'-bubbled crystal was grown, but this was done by a pulling method.

In the pulling method, since crystal growth follows the simple solidification method, the degree of a of the crystal obtained is not uniform in the length direction, and an expensive crucible is used, resulting in high cost and the risk of contamination with impurities.

In addition, there is a report by Kojima et al. on the production of forsterite containing metal atoms as a coloring component using an infrared concentrated heating single crystal production device, but these have been reported that divalent metals such as cobalt atoms and nickel atoms are the cause of the coloration. It contains ions.

It does not contain octavalent metals.

[Means for solving problems]

The present inventors succeeded in producing a dark blue forsterite single crystal by precipitating a solid phase at one solid-liquid interface of magnesium oxide and siliceous oxide (crystallization). With the invention, it has become possible to easily and inexpensively produce Ps for a dark blue forsterite single crystal with nine different shades of color, no bubbles, no inclusions, etc.

In the present invention, the method for forming a molten zone is a method using a high-temperature heating element at °C, a method using a high-frequency induction heating method,
There are heating methods such as lasers and carbon arcs, but among them, infrared concentrated heating methods using a halogen lamp or a single Canon lamp produce good results because the output of the radiation source is stable and the heating efficiency is high.

An example of an embodiment of the invention is shown in FIGS. 1 and 2.

The spheroidal elliptical body 1 has two foci in the single-coast type, and eight foci in the double-coat type.
The figure shows a bielliptic shape. A halogen lamp or a xenon lamp 2 is placed at one focal point in the single circular type, and at both ends of the focal point in the double circular type, and a rod-shaped raw material 8 is placed at the remaining focal points. The rod-shaped raw material 8 is held by the upper rotating shaft 4. Further, the seed crystal 5 is set on the lower rotating shaft 6. Rod-shaped raw material 3
゜Seed crystal 5. The underground rotating shaft 4.6 is enclosed in a transparent quartz tube T, and the surrounding atmosphere can be freely controlled, and it is possible to use not only atmospheric pressure but also vacuum or pressurization.

The reason why the temperature of the rod-shaped raw material 8 rises and the molten i8 is formed is as follows.
This is the part that is completely in focus. The molten zone 8 is the rotating shaft 4
．． 6 is placed upward to form Ise C melt 44f8, and then the seed crystal 5 is moved upward and melted? Make contact with 4f8. After confirming that an equilibrium state has been reached, the melt moves about the rotation axis 4.6, and crystallization occurs at the interface between the 18 melt 44f8 and the seed crystal 5.

Further, the present invention can be carried out more effectively by installing a heat radiation prevention tube and/or an after-heater 9 so as to surround the vicinity of the corner of the melting zone 8, as shown in FIG. In other words, this allows the solid-liquid interface to be leveled when the solid phase is precipitated and crystallized from the molten zone, and a better quality single crystal can be obtained. Refers to tubes such as pure alumina tubes that do not melt during the formation of a molten zone and are less likely to be contaminated with impurities.
Also, the after-heater is itself a heating element,
It can be used alone or in combination with a heat radiation prevention tube.

The method of the present invention has a number of features and advantages, including:

1) Operational safety is very high because high temperatures can be easily obtained. For example, in the case of the Bernoulli method, a high degree of chicness is required because oxygen gas and hydrogen gas are used, and there is always a danger of explosion, whereas with the Bernoulli method, it is easy to operate and does not require special experience or technique. Also, there is no danger at all.

2) Unlike the pulling method, which does not use a crucible, there is very little contamination of impurities.

8) Furthermore, in the case of a concentrated infrared heating method using a halogen lamp or a xenon lamp, the output of the lamp is stable and the temperature can be easily controlled. Therefore, the molten zone is very stable, and crystallization can occur without necessarily using a seed crystal.

4) The melting state and crystal growth can be easily observed.

5) As a result, high-purity, high-quality crystals can be easily and safely produced.

The highly densely sintered rod-shaped raw materials made of magnesium oxide, silicon oxide, and trichromium oxide used in the present invention are:
It is obtained by molding these mixtures into rod shapes using a rubber press, for example, and sintering them at 800"C to 1800°C.Furthermore, the starting materials for the rod-shaped raw materials may be magnesium oxide, silicon oxide, or chromium ditrioxide itself. However, magnesium compounds, silicic acid compounds, and chromium compounds such as carbonates and hydroxides, which become magnesium oxide, silicon oxide, and chromium ditrioxide after sintering, may also be used.

In the present invention, C contains 40 to 80 mole percent of magnesium oxide and 20 to 20 mole percent of silicon oxide. If magnesium oxide and silicon oxide do not reach 40 mol percent and 20 mol percent, respectively, or exceed 80 mol percent and 50 mol percent, respectively, crystal formation becomes unstable and good quality crystals cannot be obtained. If the amount of chromium ditrioxide does not reach 0.01 mol percent, almost no dark blue coloration is observed, and crystallization is hindered due to poor infrared absorption ability. On the other hand, if there is a 100 mole percent difference, segregation may occur in the crystal, forming inclusions and deteriorating the crystallinity of C.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1゜Mg (COs)・Mg (OH)2・51111gO
Special grade reagent, 8 i02 special grade reagent and Crg's special grade reagent are used as starting materials.

The molar ratio of each raw material is MgO: 8i02: 0r20
8 = 66.4: 38.2: 0.4, and uniformly mixed using ethanol in a mortar. This was dried in the air and fired at 1100'C for 8 hours in the air. Then grind and mix well in a mortar.

801ffX8fl diameter size + c tt filter Ic
After molding using a rubber press method under a hydrostatic pressure of 700 kq/cd, the material was sintered at 1600°C for 5 hours to obtain a rod-shaped raw material.

The equipment is a twin-inert circular type infrared concentrated heating single crystal production system! It is made by Chia 2 Machinery) and halogen lamp (1゜5 Kml) 2
We used

The seed crystal used was a single crystal formed from a polycrystalline body, which was then cut out in an appropriate orientation by the back Lau flow method.

The atmosphere was air flowing at a rate of 601/h.

The rotation speed of the rotating shaft is such that the raw material rod and seed crystal are moved in opposite directions.
Rotate each at a speed of 30 revolutions per minute, W growth rate I Ji
g/hr. The obtained crystal was a dark blue transparent single crystal. No twins, bubbles, or inclusions were observed. The results of X-ray diffraction also confirmed that it was a forsterite single crystal. The lattice constant was almost the same as that without chromium ions. The hardness was 6.5 to 7, which was harder than rutile and slightly softer than quartz.

Example 2゜Mg (COa) + Mg (QH)2 ・5 [2
Using 0 special grade reagent, 5 in 2 special grade reagent and Or20g special grade reagent as starting materials.

The molar ratio of each raw material is MgO: 8i02: 0r20
Weighed so that s = 66.2: 88.1: 0.7, and prepared as Example 1. A rod-shaped raw material was obtained by mixing and sintering in the same manner as above. The device uses a twin circular infrared concentrated heating single crystal production device A1 (manufactured by Chia 2 Kikai), a high purity alumina tube with a diameter of 20 fins is installed as a heat radiation prevention tube on the single crystal side near the condensing part, and a halogen lamp is installed. (W for 1 and 5) 2 pieces were used.

The seed crystal used was one grown in Example 1 and cut out in an appropriate orientation by the back-face Rau 1 method.

The atmosphere is 1801. 'br was washed away. The rotation speed of the rotating shaft was such that the raw material rod and the seed crystal were rotated in opposite directions at a speed of 25 revolutions per minute, and the growth rate was 1 tz/hr. The obtained crystals are as shown in Example 1. The single crystal had a deeper dark blue color than the single crystal obtained in . Twins, bubbles.

No inclusions were observed. The results of X-ray diffraction also confirmed that it was a forsterite single crystal. The lattice constant was T, which was almost different from that without chromium ions. Hardness is harder than rutile.

It was 6.5 to 7, which is a little softer than crystal.

[Effects of the present invention]

According to the present invention, a dark blue forsterite single crystal can be produced easily and at low cost.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams explaining the principle of the method of the present invention. 1... Spheroidal mirror body 2... Halogen lamp or xenon lamp 8... Rod-shaped raw material 4... Upper rotating shaft 5... Seed crystal 6... Lower rotating shaft 7. ...
Quartz tube 8: Melting zone 9: After-heater or/and heat radiation prevention tube Applicant: Representative of Tetsu Seikagaku Kogyo Co., Ltd. 1) Hiroshi Yutaka

Claims (4)

[Claims] (1) Magnesium oxide (MgO), silicon oxide (Si)
O_2) and 3 of chromium ditrioxide (Cr_2O_8)
A molten body is formed at one end of the sintered rod-shaped raw material made of the ingredients, the molten zone is moved, the raw material is melted at one solid-liquid interface of the molten zone, and the solid phase is precipitated at the other solid-liquid interface and crystallized. A method for producing a dark blue forsterite single crystal, characterized by carrying out the following steps. (2) The composition of the rod-shaped raw material is magnesium oxide 40 to 8
0 mole percent, silicon oxide 20 to 50 mole percent, trichromium oxide 0.01 to 10 mole percent. (3) The manufacturing method according to claim (1), which uses a device that concentrates infrared rays to form a molten zone. (4) A patent for installing a heat radiation prevention tube and/or an after-heater in the device so as to surround the lower part of the melting zone so as to keep the solid-liquid interface horizontal when the solid phase is precipitated and crystallized from the melting zone. Manufacturing method according to claim (3).