Abstract: A sputtering target which is made of an alumina sintered body having a purity of not less than 99.99% by mass %, a relative density of not less than 98%, and an average grain size of less than 5 ?m or is made of an alumina sintered body having a purity of not less than 99.999% by mass % and a relative density of not less than 98%. A sputtered film having an excellent insulation resistance and an excellent homogeneity can be obtained by using the sputtering target.

Abstract: A sputtering target which is made of a magnesium oxide sintered body having a purity of not less than 99.99% or not less than 99.995% by mass %, a relative density of not less than 98%, and an average grain size of not more than 8 ?m. The average grain size of the sputtering target is preferably not more than 5 ?m, more preferably not more than 2 ?m. A sputtered film having an excellent insulation resistance and an excellent homogeneity can be obtained by using the sputtering target.

Abstract: A sputtering target which is made of an alumina sintered body having a purity of not less than 99.99% by mass %, a relative density of not less than 98%, and an average grain size of less than 5 ?m or is made of an alumina sintered body having a purity of not less than 99.999% by mass % and a relative density of not less than 98%. A sputtered film having an excellent insulation resistance and an excellent homogeneity can be obtained by using the sputtering target.

Abstract: Disclosed is a surface-treated ceramic member which has a coating film-formed surface comprising a ceramic sintered body with a porosity of 1% or less and a sol-gel coating film of a silicon alkoxide compound polymer formed on at least a part of a ceramic sintered body, wherein the coating film and the surface of the body are coexistent in the coating film-formed surface. Specifically the area of the sol-gel coating film accounts for 5 to 80% of the total area of the coating film-formed surface. The surface-treated ceramic member has excellent corrosion resistance and is free from scattering of particles.

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 ? of 1×10?4 or 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 ?m 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 (?m) 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.

Abstract: Disclosed is a surface-treated ceramic member which has a coating film-formed surface comprising a ceramic sintered body with a porosity of 1% or less and a sol-gel coating film of a silicon alkoxide compound polymer formed on at least a part of a ceramic sintered body, wherein the coating film and the surface of the body are coexistent in the coating film-formed surface. Specifically the area of the sol-gel coating film accounts for 5 to 80% of the total area of the coating film-formed surface. The surface-treated ceramic member has excellent corrosion resistance and is free from scattering of particles.

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). Solution An Yttria sintered body having a dielectric loss tan ? of 1×10?4 or 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 ?m or less, and the cumulative frequency ratio calculated from the following formula (1) is 3 or less: Cumulative frequency ratio=D90/D50 ??(1) In the above-described formula (1), the meanings of the individual symbols are as follows: D90: The crystal grain size (?m) 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.