The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 17, 2012
Filed:
Oct. 27, 2010
Ken Okamoto, Amagasaki, JP;
Tadahisa Arahori, Ashiya, JP;
Ken Okamoto, Amagasaki, JP;
Tadahisa Arahori, Ashiya, JP;
Ferrotec Ceramics Corporation, Tokyo, JP;
Abstract
To provide a high purity Yttria sintered bodies having a high strength, a low dielectric loss and high plasma corrosion resistance of halogen gas during wide range surface roughness (Ra). An Yttria sintered body having a dielectric loss tan δ of 1×10or less in the frequency range from 1 to 20 GHz, wherein the Yttria sintered body contains Yttria of 99.9% by mass or more, has a porosity of 1% or less and an average crystal grain size of 3 μm or less, and the cumulative frequency ratio calculated from the following formula (1) is 3 or less: Cumulative frequency ratio=D90/D50. In the above-described formula (1), the meanings of the individual symbols are as follows: D90: The crystal grain size (μm) at which the cumulative number of grains as calculated from the smaller grain size side is 90% in the grain size distribution of the crystal grains in terms of the number of grains. D50: The crystal grain size (μm) at which the cumulative number of grains as calculated from the smaller grain size side is 50% in the grain size distribution of the crystal grains in terms of the number of grains.