Tb-CONTAINING RARE EARTH-ALUMINUM GARNET CERAMIC, AND METHOD FOR MANUFACTURING SAME

A method for producing a Tb-containing rare earth-aluminum garnet ceramic, the method comprising:

• (1) a step for wet mixing
• (1-1) a mixed powder raw material which contains (a) a terbium oxide having an average primary particle diameter of 1 μm or less, (b) an aluminum oxide having an average primary particle diameter 1 μm or less, (c) a calcium compound having an average primary particle diameter of 1 μm or less or a magnesium compound having an average primary particle diameter of 1 μm or less, and (d) a silicon compound having an average primary particle diameter of 1 μm or less, and which has a stoichiometric garnet composition, or
• (1-2) a mixed powder raw material which contains (a) an oxide which has an average primary particle diameter of 1 μm or less and is represented by the formula (TbxRe1-x)3(AlySc1-y)5O12 wherein Re is at least one element selected from a group consisting of Y and Lu, x=1.0-0.5, and y=1.0-0.6, (b) a calcium compound having an average primary particle diameter of 1 μm or less or a magnesium compound having an average primary particle diameter of 1 μm or less, and (c) a silicon compound having an average primary particle diameter of 1 μm or less, and which has a stoichiometric garnet composition
• in an alcohol to obtain a mixture;
• (2) a step for press molding this mixture to obtain a green compact;
• (3) a step for subjecting the green compact to preliminary sintering at a temperature of 1450 to 1600° C. to obtain a preliminary sintered body having a relative density of 95 to 99%;
• (4) a step for subjecting the preliminary sintered body to a HIP treatment at a temperature of 1500 to 1680° C. and a pressure of 49 to 196 MPa;
• and
• (5) a step for annealing the HIP-treated sintered body at a temperature of 1200 to 1500° C.