| abstract |
A method for preparing an oxide powder, which comprises holding in a fluidiz ed state a base material powder comprising a first oxide and having an adsorbed water content of 0.1 to 50 %, an average particle size of 0.005 to 0.5 .mu.m and a number of surface hydroxyl groups of 0.1 to 25 .mu.mol/m2, contacting the base material powder held in a fluidized state with a halide or an alkoxide containing a metal or semi-metal being the same as or different fro m that of the first oxide together with an inert carrier gas while heating it to a temperature of 25 to 800~C, to thereby coat the base material powder with a coating film comprising a second oxide, and then heating reaction by-product s comprising a hydrogen halide or alcohol formed by the above contacting to a temperature of 200 to 1000~C, to thereby remove the by-products. The method can be employed for forming, on the surface of the base material powder of a first oxide, a coating film comprising a second oxide being the same as or different from the first oxide, with homogeneity and at a low cost by a chemical procedure, and thus for providing a base material powder and a coating film layer having satisfactory physical and chemical characteristics . |