| abstract |
A method of synthesizing negative-thermal-expansion ceramics of synthesizing Zr (1−x) X x W 2 O 8 in which X represents a substituent element for zirconium Zr, and 0≦x <<1, having a negative thermal expansion coefficient, the method comprising mixing two mols of tungsten trioxide WO 3 and one mol of the sum of zirconium oxide ZrO 2 and a substituent element X in accordance with substitution amount x at a stoichiometrical ratio, further mixing the thus obtained starting material in a powdery form having a particle size distribution including two groups of particles comprising smaller diameter particles with a particle size of 0.1 to 1 μm and larger diameter particles with a particle size of 5 to 50 μm, and then sintering the staring powder being placed in a desired molding die whereby negative-thermal-expansion ceramics having an increased density equal with or higher than that of press molding products and of a larger size than that of the press molding products without press-molding the starting powder can be synthesized. |