Lithium tantalate single crystal growth from a platinum-rhodium crucible in an inert gas, nitrogen or reducing gas atmosphere

• US 4,135,963 A
• Filed: 11/23/1977
• Issued: 01/23/1979
• Est. Priority Date: 11/25/1976
• Status: Expired due to Term

• Current Assignee: Tokyo Shibaura Electric Co., Ltd.
• Original Assignee: Tokyo Shibaura Electric Co., Ltd.
• Inventors: Fukuda, Tsuguo
• Primary Examiner(s): Emery, Stephen J.
• Application Number:
  US05/854,075
• Time in Patent Office: 426 Days
• Field of Search: 156/DIG. 87, 156/617 SP, 156/DIG. 83, 156/DIG. 97, 156/DIG. 96, 75/172 E, 432/265, 252/62.9 R, 23/273 SP, 423/65, 423/184, 423/593
• US Class Current: 117/13
• CPC Class Codes: C30B 15/00 Single-crystal growth by pulling from a melt, e.g. Czochralski method under a protective fluid C30B27/00
• CPC Class Codes: C30B 15/10 Crucibles or containers for supporting the melt
• CPC Class Codes: C30B 29/30 Niobates; Vanadates; Tantalates
• CPC Class Codes: Y10S 117/90 Apparatus characterized by composition or treatment thereof, e.g. surface finish, surface coating
• CPC Class Codes: Y10S 117/906 Special atmosphere other than vacuum or inert

Abstract

A method of producing a single crystal of lithium tantalate in a platinum-rhodium crucible containing 20 to 40% by weight of rhodium in an atmosphere of reducing or inert gas.

Claims

1. A method of manufacturing a single crystal of lithium tantalate by bringing a seed crystal of lithium tantalate into contact with a melt consisting essentially of lithium tantalate in a crucible and pulling the molten mass containing said seed crystal out of the crucible to form said single crystal, the improvement comprising forming a single crystal from said melt in said crucible, said crucible consisting essentially of a platinum-rhodium alloy containing between 20 and 40% by weight rhodium, in an atmosphere selected from the group consisting of nitrogen, reducing gas, inert gas, and mixtures thereof, supplied at a flow rate between 0.1 and 10 liters per minute, to form a lithium tantalate single crystal containing between 5 and 30 ppm by weight rhodium.

2. The method according to claim 1, wherein said atmosphere is nitrogen gas.

3. The method according to claim 1, wherein said atmosphere is hydrogen gas.

4. The method according to claim 1, wherein the single crystal of lithium tantalate is manufactured in an atmosphere formed of a mixture of said gases.