Preparation of various NASICON-type crystalline zirconium phosphates

The proton-type crystalline zirconium phosphate, HZr2(PO4)(3), was prepared by a thermal decomposition of NH4Zr2 (PO4)(3) at about 680 degreesC, where NH4Zr2(PO4)(3) was obtained in advance by a hydrothermal synthesis using a mixed solution of ZrOCl2, H3PO4 and H2C2O4. This zirconium phosphate was, then, mixed with other metal nitrate, M(NO3)(n) (M=Li, Na, K, Rb, Sr, Bi, Y, Mg, Ca, Sc, Mn, Fe, Ca, Ni, Cn, Zn, Ag, Cd, Ca, Ba, La, Ce, Tl or Ph; n=1, 2 or 3), at room temperature. The TG-DTA curves of these mixtures showed an endothermic weight loss around melting or decomposition temperature of each metal nitrate as a component. From these results, calcination temperature, which is in the range of 500-800 degreesC and 100-200 degreesC higher than the endothermic peak temperature, was determined for each mixture, in order to eliminate the unreacted components. All products thus calcined gave the XRD patterns attributable to M {Zr-2(PO4)(3)}(n) (n=1 for M (I), n=2 for M(II) and n=3 for M(III)) with a NASICON-type structure.