Synthesis and structure of complex orthophosphates of zirconium and alkalielements: 3. Isomorphism in Li-Zr, Na-Zr, and K-Zr phosphates

Orthophosphates of zirconium and alkali metals (Li, Na, K) were prepared an d studied by IR spectroscopy and X-ray diffraction. Single-phase phosphates with the structure similar to NaZr2(PO4)(3) (space group R (3) over bar c) were found in the series of compounds with mutually different alkali eleme nts A'(1-x)A(x)" Zr-2(PO4)(3) (0 less than or equal to x less than or equal to 1) and A'(5-x)A(x)" Zr(PO4)(3) (0 less than or equal to x less than or equal to 5), where A' and A " are Li, Na, and K, and the dependences of the crystal structure of these phases on their chemical composition were evalu ated. Simultaneous participation of lithium, sodium, and potassium in the s tructure of phosphates, including substitution solid solutions, is due to o ccupation of three types of nonequivalent crystallographic points by alkali elements. Single-phase zirconium phosphate formulations with high concentr ation of alkali elements in various ratios can be obtained.