Garnet single crystal and method for producing the same

Patent metadata

Field	Value
Publication number	US-2016145765-A1
Application number	US-201414787954-A
Country	US
Kind code	A1
Filing date	Mar 20, 2014
Priority date	Jun 17, 2013
Publication date	May 26, 2016
Grant date	—

Abstract

[Object] To provide a high-quality, transparent garnet single crystal with suppressed cell growth that would otherwise lead to partially inhomogeneous crystal composition, and a method for producing the garnet single crystal. [Solving means] The garnet single crystal is grown by bringing a seed crystal into contact with a raw-material melt in a crucible disposed inside a chamber and pulling, while rotating, the seed crystal. The garnet single crystal is characterized by being represented by a general formula: (Tb 3-x Sc x ) (Sc 2-y Al y )Al 3 O 12-z (provided that 0.11≦x≦0.14, and 0.17≦y≦0.23). The garnet single crystal is grown as follows. First, a mixture powder containing 20.9 to 21.2% by mole terbium oxide, 32.7 to 33.3% by mole scandium oxide, and the balance of aluminium oxide and unavoidable impurities is filled into the crucible and melted. Then, while a nitrogen gas is supplied into the chamber, the number of rotations of the seed crystal is set to 5 to 20 rpm, and the rate of pulling the seed crystal is set to 0.3 to 0.8 mm/h for the growth.

First claim

1 . A garnet single crystal characterized in that the garnet single crystal is represented by the following general formula:
(Tb 3-x Sc x )(Sc 2-y Al y )Al 3 O 12-z   (1)
(where x satisfies 0.11≦x≦0.14, and y satisfies 0.17≦y≦0.23).

2 . A method for producing a garnet single crystal using a growth furnace including a crucible in a cylindrical chamber by a Czochralski process for growing a garnet single crystal by bringing a seed crystal into contact with a raw-material melt in the crucible and pulling, while rotating, the seed crystal, characterized in that the production method comprises:
preparing the raw-material melt by filling the crucible with a mixture powder containing 20.9 to 21.2% by mole terbium oxide, 32.7 to 33.3% by mole scandium oxide, and the balance of aluminium oxide and unavoidable impurities, followed by melting of the mixture powder; and growing the garnet single crystal according to claim 1 , while supplying an inert gas into the chamber, by setting conditions such that the number of rotations of the seed crystal is 20 rpm or less, and a rate of pulling the seed crystal is 0.8 mm/h or less.

3 . The method for producing a garnet single crystal according to claim 2 , characterized in that the conditions are set such that
the number of rotations of the seed crystal is from 5 rpm or more to 20 rpm or less, and the rate of pulling the seed crystal is from 0.3 mm/h or more to 0.8 mm/h or less.

4 . The method for producing a garnet single crystal according to claim 2 , characterized in that the inert gas is supplied into the chamber at a flow rate of from 3 L/min or more to 6 L/min or less.

5 . The method for producing a garnet single crystal according to claim 3 , characterized in that the inert gas is supplied into the chamber at a flow rate of from 3 L/min or more to 6 L/min or less.

6 . The method for producing a garnet single crystal according to claim 2 , characterized in that the inert gas is a nitrogen gas.

7 . The method for producing a garnet single crystal according to claim 3 , characterized in that the inert gas is a nitrogen gas.

8 . The method for producing a garnet single crystal according to claim 4 , characterized in that the inert gas is a nitrogen gas.

9 . The method for producing a garnet single crystal according to claim 5 , characterized in that the inert gas is a nitrogen gas.

Assignees

• Sumitomo Metal Mining Co
• Sumitomo Metal Mining Co

Inventors

• Matsui Masayoshi
• Tatsumiya Kazuki
• Ishida Fumiaki

Classifications

• C30B15/20 Primary

  Controlling or regulating (controlling or regulating in general G05) · CPC title

• C30B29/20

  Aluminium oxides · CPC title

• C30B15/30 Primary

  Mechanisms for rotating or moving either the melt or the crystal (flotation methods C30B15/28) · CPC title

• G02F1/093

  used as non-reciprocal devices, e.g. optical isolators, circulators (G02F1/0955 takes precedence) · CPC title

• G02F1/0036

  Magneto-optical materials · CPC title