LIGHT-TRANSMISSIVE POLYCRYSTALLINE MATERIAL AND METHOD FOR PRODUCING THE SAME
Provided is a method for producing a light-transmissive polycrystalline material wherein a suspension (slurry 1) is prepared by suspending, in a solution, a starting powder which comprises optically-anisotropic single crystal grains to which a rare earth element has been added. A molded article is obtained from the suspension by slip casting within the space of a magnetic field. The temperature is controlled at this time such that the single crystal grains demonstrate a predetermined magnetic anisotropy while a static magnetic field or a rotary magnetic field is selected and applied in the direction of the easy axis of magnetization of the single crystal grains. The molded article is baked to obtain a light-transmissive polycrystalline material having a polycrystalline structure wherein the crystal orientation is controlled. During this baking step, the molded article is subjected to primary sintering at a temperature of 1,600 to 1,900 K and the primary sintered compact is then subjected to hot isostatic pressing (HIP treatment) at a temperature of 1,600 to 1,900 K.