# US 11,299,818 B2 · Method for producing PbTiO3-containing single crystal

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- Number: US 11,299,818 B2
- Document ID: US11299818B2
- Status: Granted
- Kind: B2
- Application number: 16/312,109
- Filed: 2017-06-28
- Published: 2019-07-25
- Granted: 2022-04-12
- Earliest claimed: 2016-09-12
- Assignees: Jfe Mineral Company, Ltd.
- Applicants: Jfe Mineral Company, Ltd.
- Inventors: Kazuhiko Echizenya
- Web page: https://patentgrep.com/patent/US11299818B2

## CPC

- C30B 11/02: without using solvents (C30B11/06 takes precedence)
- C30B 11/00: Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method (C30B13/00, C30B15/00, C30B17/00, C30B19/00 take precedence; under a protective fluid C30B27/00)
- C30B 29/32: Titanates; Germanates; Molybdates; Tungstates
- 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

## Abstract

Provided is a method for producing a single crystal, wherein compositional variations and defects in the single crystal can be prevented and a single crystal having uniform characteristics in the growth direction can be produced at high yield. In this method for producing a single crystal, a PbTiO3-containing single crystal is produced by the vertical Bridgman technique, wherein the thickness of a melt layer containing the melt in a crucible is at least 30 mm.

## Claims

### Claim 1

A single crystal production method for producing a single crystal containing PbTiO3 by a vertical Bridgman method while heating and melting a raw material to obtain a melt and supplying the melt, comprising:
supplying an initial raw material in solid form to a cone part of a crucible and an adjacent region above said cone part,
heating and melting the initial raw material in the crucible to form a melt layer on an upper side of a seed crystal, wherein said melt layer has a predetermined thickness of at least 30 mm in said adjacent region above said cone part,
lowering the crucible in an environment having a temperature gradient in which the temperature at a lower section becomes lower,
starting unidirectional solidification of said melt layer from a part coming into contact with the seed crystal,
solidifying said melt layer up to an upper end face of the cone part,
dropping the additional melt obtained by heating and melting a raw material in a sub-crucible into the crucible,
lowering the crucible while maintaining said predetermined thickness of said melt layer in said adjacent region above said cone part by balancing and adjusting the speed of lowering the crucible and supply rate by dropping of the additional melt, and
producing the single crystal.

### Claim 2 (depends on 1)

The single crystal production method according to claim 1, wherein said predetermined thickness is set to 30 to 90 mm.