Abstract: An aqueous solution of mixed metal acetate including one kind or more of element selected from lanthanide series and yttrium, barium and copper is mixed with trifluoroacetic acid to prepare a solution of mixed metal trifluoroacetate. From a solution of mixed metal trifluoroacetate obtained thus, purified mixed metal trifluoroacetate of which total content of water and acetic acid is 2% by weight or less is prepared. With purified mixed metal trifluoroacetate, an oxide superconductor of excellent performance may be prepared.

Abstract: A process for producing a high purity and dense calcium phosphate coating film with bioaffinity on a high strength base, such as a base for a substitute for a hard tissue in a living body, comprising (1) dissolving (a) a salt containing phosphorus, a salt containing calcium, and a chelating agent capable of coordinating to either one or both of the metallic ions of these salts or (b) a chelate compound containing at least one of phosphorus and calcium and a salt containing the other in a solvent to prepare a sediment-free coating solution, (2) coating a base with the coating solution, (3) drying the coated base, and (4) calcining the coated base.

Abstract: A biocompatible implant material is disclosed comprising (i) particles connected each other and (ii) vacant spaces comprising three-dimensionally interconnected pores present among the particles, wherein the particles have an average size of 10 to 800 .mu.m and the pores have a size of 2 to 800 .mu.m, and the process for producing the biocompatible implant material which comprises granulating a raw powder having an average particle size of 5 .mu.m or smaller to give raw granules having an average particle size of 10 to 800 .mu.m, mixing the raw granules with a combustible substance having an average particle size of 2 to 1,600 .mu.m, pressing the mixture into a shape at a pressure of 1 to 100 kg/cm.sup.2, and then firing the shape.