# US 7,744,696 B2 · Method for preparing borate-based crystal and laser oscillation apparatus

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- Number: US 7,744,696 B2
- Document ID: US7744696B2
- Status: Granted
- Kind: B2
- Application number: 10/545,314
- Filed: 2004-02-13
- Published: 2006-05-18
- Granted: 2010-06-29
- Earliest claimed: 2003-02-13
- Assignees: Japan Science and Technology Agency
- Inventors: Takatomo Sasaki; Yusuke Mori; Masashi Yoshimura; Muneyuki Nishioka; Satoru Fukumoto; Tomoyo Matsui; Takashi Saji
- Web page: https://patentgrep.com/patent/US7744696B2

## CPC

- C30B 35/007: {Apparatus for preparing, pre-treating the source material to be used for crystal growth}
- C01B 35/12: Borates {(C01B35/1063 takes precedence)}
- C30B 11/02: without using solvents (C30B11/06 takes precedence)
- C30B 29/22: Complex oxides
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}

## Abstract

A borate-based crystal excellent in uniformity and reliability, which is useful as an optical wavelength conversion device, etc., and can be easily produced at low cost in a short period of time, by the steps of dissolving water-soluble starting materials in water to prepare an aqueous solution, evaporating water in the aqueous solution followed by sintering or evaporating the water and not sintering, thereby forming a crystal growth material, and melting the resultant material to grow a crystal. Further, a highly reliable laser oscillation apparatus can be achieved by using this crystal as an optical wavelength conversion device.

## Claims

### Claim 1

A method for producing a borate-based crystal, which comprises:
employing a water-soluble cesium compound and a water-soluble boron compound as starting materials,
dissolving all of the starting materials simultaneously in an amount of water which is 1.0 to 2.5 times the total weight of the starting materials,
forming an aqueous solution with a uniform composition,
evaporating the water in the aqueous solution, followed or not followed by sintering, to form a crystal growth material,
melting the crystal growth material, and
growing a cesium-borate-based crystal of the composition formula:
Cs1-xMxB3O5 (0≦x<1)
wherein M is an alkaline metal or alkaline earth metal element,
wherein the water-soluble cesium compound is a cesium carbonate compound, and
wherein a decarboxylation reaction occurs in the aqueous solution by dissolving the starting materials in water.

### Claim 2 (depends on 1)

The method for producing a borate-based crystal according to claim 1, wherein the water-soluble boron compound is boron oxide or boric acid.

### Claim 3 (depends on 1)

The method for producing a borate-based crystal according to claim 1, wherein the aqueous solution is heated to evaporate the water.

### Claim 4 (depends on 1)

The method for producing a borate-based crystal according to claim 1, wherein the sintering is carried out within a temperature range of 500° C. or higher and lower than the melting temperature after evaporating the water in the aqueous solution.

### Claim 5 (depends on 1)

The method for producing a borate-based crystal according to claim 1, wherein a melt of the crystal growth material is stirred during the crystal growth.

### Claim 6 (depends on 1)

The method for producing a borate-based crystal according to claim 1, wherein the grown crystal is heated to reduce a water impurity in the crystal.

### Claim 7 (depends on 6)

The method for producing a borate-based crystal according to claim 6, wherein the grown crystal is heated at 100° C. or higher.

### Claim 8 (depends on 6)

The method for producing a borate-based crystal according to claim 6, wherein the grown crystal is heated in a gas-substituted atmosphere or an evacuated atmosphere.