JPH0232216B

PURPOSE:To manufacture the titled hyperfine powder having high crystallizability at a relatively low temp. in a short time by adding a nitrogen compound which generates ammonia by decomposition to an aqueous soln. contg. a zirconium salt and by treating the soln. in an autoclave. CONSTITUTION:A compound which generates ammonia by decomposition such as urea or cyanate is added to an aqueous soln. of a zirconium salt such as zirconium oxychloride or an aqueous soln. contg. a zirconium salt and a salt of a desired metal such as Mg, Ca or Y which provides high toughness or stability, and the soln. is treated in an autoclave to manufacture the titled hyperfine powder having a uniform particle size and causing no coagulation. Since unlike a conventional slow reaction a rapid reaction is carried out by the autoclave treatment with the nitrogen compound which generates ammonia by decomposition, the titled hyperfine powder having high crystallizability can be synthesized at a relatively low temp. in a short time, thus, the manufacturing cost can be reduced.