METHOD FOR PRODUCING TRANSPARENT CERAMIC, TRANSPARENT CERAMIC, MAGNETO-OPTICAL DEVICE AND RARE EARTH OXIDE POWDER FOR SINTERING

• US 20170205643A1
• Filed: 06/01/2015
• Published: 07/20/2017
• Est. Priority Date: 06/04/2014
• Status: Active Grant

• Current Assignee: Shin-Etsu Chemical Company Limited
• Original Assignee: Shin-Etsu Chemical Company Limited
• Inventors: Makikawa, Shinji, Nojima, Yoshihiro, Aoki, Shinji
• Granted Patent: US 10,642,073 B2
• Time in Patent Office: Days
• CPC Class Codes: C01F 17/00 Compounds of rare earth metals
• CPC Class Codes: C01F 17/224 Oxides or hydroxides of lanthanides
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/60 Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
• CPC Class Codes: C04B 2235/9653 Translucent or transparent ceramics other than alumina
• CPC Class Codes: C04B 35/50 based on rare-earth compounds non-oxide rare earth compounds C04B35/5156
• CPC Class Codes: C04B 35/505 based on yttrium oxide
• CPC Class Codes: C04B 35/6264 Mixing media, e.g. organic solvents
• CPC Class Codes: C04B 35/6303 Inorganic additives
• CPC Class Codes: C04B 35/64 Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: C04B 35/645 Pressure sintering
• CPC Class Codes: G02B 27/28 for polarising used in stereoscopes G02B30/25
• CPC Class Codes: G02F 1/0036 Magneto-optical materials
• CPC Class Codes: G02F 1/09 based on magneto-optical elements, e.g. exhibiting Faraday effect
• CPC Class Codes: G02F 1/093 used as non-reciprocal devices, e.g. optical isolators, circulators G02F1/0955 takes precedence

Abstract

A starting material powder, which contains a rare earth oxide that is composed of terbium oxide and at least one other rare earth oxide selected from among yttrium oxide, scandium oxide and oxides of lanthanide rare earth elements (excluding terbium) and a sintering assistant that is formed of an oxide of at least one element selected from among group 2 elements and group 4 elements, is produced by having (a) terbium ions, (b) ions of at least one other rare earth element selected from among yttrium ions, scandium ions and lanthanide rare earth ions (excluding terbium ions) and (c) ions of at least one element selected from among group 2 elements and group 4 elements coprecipitate in an aqueous solution containing the components (a)-(c), then filtering and separating the coprecipitate, and subjecting the separated coprecipitate to thermal dehydration.

Claims

1. A method for producing a transparent ceramic containing terbium oxide (chemical formula:

Tb₂O₃) and at least one other rare earth oxide selected from among yttrium oxide, scandium oxide and oxides of lanthanide rare earth elements (excluding terbium) as main components, the method comprising;

subjecting an aqueous solution containing (a) terbium ions, (b) ions of at least one other rare earth element selected from among yttrium ions, scandium ions and lanthanide rare earth ions (excluding terbium ions) and (c) ions of at least one element selected from among Group 2 elements and Group 4 elements to co-precipitation of the components (a), (b) and (c), filtration and separation of the co-precipitate and thermal dehydration, to form a raw material powder containing a rare earth oxide including terbium oxide and at least one other rare earth oxide selected from among yttrium oxide, scandium oxide and oxides of lanthanide rare earth elements (excluding terbium), the molar ratio of terbium oxide being at least 40 mol % and the balance being the other rare earth oxide, and a sintering aid including an oxide of at least one element selected from among Group 2 elements and Group 4 elements;

forming a molded body using the raw material powder;

then firing the molded body; and

subjecting the fired molded body to pressure firing.

2. The method for producing a transparent ceramic of claim 1, wherein the raw material powder contains more than 0.5 parts by weight and up to 5 parts by weight of the sintering aid per 100 parts by weight of the rare earth oxide.

3. The method for producing a transparent ceramic of claim 1, wherein the component (c) is ions of at least one element selected from among titanium ions, zirconium ions, hafnium ions, calcium ions and magnesium ions.

4. The method for producing a transparent ceramic of claim 1, further comprising subjecting the pressure-fired molded body to a heat treatment at 1,500 to 2,000°

C. in a non-oxidizing atmosphere.

5. The method for producing a transparent ceramic of claim 1, wherein the molded body is calcined before the firing.

6. A transparent ceramic produced by the method for producing a transparent ceramic of claim 1, the transparent ceramic containing a rare earth oxide including terbium oxide (chemical formula:

Tb₂O₃) and an oxide of at least one other rare earth element selected from among yttrium oxide, scandium oxide and oxides of lanthanide rare earth elements (excluding terbium), the molar ratio of terbium oxide being at least 40 mol % and the balance being the other rare earth oxide, and a sintering aid including an oxide of at least one element selected from among Group 2 elements and Group 4 elements.

7. The transparent ceramic of claim 6, wherein the content of the sintering aid is more than 0.5 parts by weight and up to 5 parts by weight per 100 parts by weight of the rare earth oxide.

8. The transparent ceramic of claim 6, wherein the sintering aid is an oxide of at least one element selected from among titanium, zirconium, hafnium, calcium and magnesium.

9. The transparent ceramic of claim 6, wherein an insertion loss at a wavelength of 1,064 nm inclusive of a reflection loss at an end face in a plane of at least 90% of a measurement surface in a thickness direction of a 10 mm-thick sample is up to 0.97 dB.

10. A magneto-optical device configured by using the transparent ceramic of claim 6.

11. A magneto-optical device wherein the transparent ceramic of claim 6 is used as a Faraday rotator.

12. The magneto-optical device of claim 11, for an optical isolator for use in a wavelength region of 1,064±

40 nm, wherein polarizing materials are provided on front and rear sides of the Faraday rotator.

13. A rare earth oxide powder for sintering containing a rare earth oxide including terbium oxide and at least one other rare earth oxide selected from among yttrium oxide, scandium oxide and oxides of lanthanide rare earth elements (excluding terbium), the molar ratio of terbium oxide being at least 40 mol % and the balance being the other rare earth oxide, and a sintering aid including an oxide of at least one element selected from among Group 2 elements and Group 4 elements, the rare earth oxide powder obtained by subjecting an aqueous solution containing (a) terbium ions, (b) ions of at least one other rare earth element selected from among yttrium ions, scandium ions and lanthanide rare earth ions (excluding terbium ions) and (c) ions of at least one element selected from among Group 2 elements and Group 4 elements to co-precipitation of the components (a), (b) and (c), filtration and separation of the co-precipitate and thermal dehydration.