| 摘要 |
<p>A cerium based composite oxide which comprises primary particles comprising 0.1 to 50 mol % in terms of oxide of at least one metal selected from among the rare earth elements except Ce and Pm, Y and Sc and 50 to 99.9 mol % in terms of oxide of Ce, and having an average aspect ratio of 1.05 to 10.0 and secondary particles formed by the coagulation of the primary particles, wherein the composite oxide comprising the primary and secondary particles has a BET specific surface area of 5 to 40 m2/g, an average particle diameter of 0.1 to 0.5 μm and a particle size distribution index represented by the following formula (1): particle size distribution index = (D84 - D16)/(2 X D50)... (1) of 1.6 or less; and a method for preparing the composite oxide. The cerium based composite oxide comprises particles of a specific needle form, has a particle size distribution being not broad, and is suppressed in coagulation of particles, and thus can provide a ceramic material excellent in sintering property.</p> |
