SYNTHESIS OF CRYSTALLINE ZIRCONIUM-PHOSPHATE WITH LARGE PARTICLE-SIZE BY THE DIRECT-PRECIPITATION METHOD

The direct-precipitation method was studied as a possible way to synthesize crystalline zirconium phosphate of a large and uniform crystal size. The yield and the crystal size were examined as functions of the initial hydrofluoric-acid and phosphroic-acid concentrations and the warming temperature. The conditions for preparing the largest crystal were: ZrOCl//2 multiplied by (times) 8H//2O, 0. 13M; hydrofluoric acid concentration, 0. 715M; phosphoric acid concentration, 5M; temperature, 50 degree C. Those for preparing the material with uniform crystal-size distribution and a possibly large-mean crystal size were: ZrOCl//2 multiplied by (times) 8H//2O, 0. 13 M; hydrofluoric acid concentration, 0. 715 M; phosphoric acid concentration, 9 M; temperature, 60 degree C. The product was confirmed to be crystalline Zr(HPO//4)//2 multiplied by (times) H//2O by means of chemical, thermal, and X-ray analyses, and by an examination of the titration curve.