Patent ID: 7470390
Filing Date: 2008-12-30
Classification: C04B,H01L

Abstract:
1. A method for producing a polycrystalline ceramic body, the polycrystalline ceramic body comprising a crystal-oriented ceramic in which a specific crystal plane A of each crystal grain is oriented, said method comprising: a preparation step of preparing a coarse particle ceramic powder having an average particle diameter of 1 to 20 μm, and a fine particle powder having an average particle diameter of ⅓ or less of the average particle diameter of the coarse particle ceramic powder and producing the polycrystalline ceramic body when sintered with the coarse particle ceramic powder, the coarse particle ceramic powder comprising a coarse particle having an oriented plane formed by orientation of a specific crystal plane, the oriented plane in said coarse particle has lattice matching with the specific crystal plane A; a mixing step of mixing the coarse particle ceramic powder and the fine particle powder to produce a raw material mixture, a forming step of forming the raw material mixture to produce a shaped body, said forming being performed to align the oriented planes of the coarse particles nearly in the same direction, and a heat-treating step of heating the shaped body, thereby shrinking said shaped body and, at the same time, sintering the coarse particle ceramic powder and fine particle powder to produce the polycrystalline ceramic body comprising the polycrystalline ceramic body in which the specific crystal plane A of each crystal grain is oriented, wherein in said heat-treating step, a temperature elevating process of starting heating the shaped body to elevate the temperature and a first holding process of holding the shaped body at a temperature T