IR study of the structure of rhombohedral zirconium and alkali metal orthophosphates

Zirconium orthophosphates with different alkali cations MZr2(PO4)(3), M2Zr( PO4)(2), and M5Zr(PO4)(3), where M is Na, K, Rb, Cs, were synthesized and s tudied by IR spectroscopy X-ray diffraction, and K-40 radiometric analysis. It is confinned that MZr2(PO4)(3) (M = Na, K, Rb, Cs) exist as rhombohedra l phases crystallizing as NaZr2(PO4)(3) (NZP) structures. For Na5Zr(PO4)(3) it is shown that an NZP phase with a monoclinic superstructure is formed a s a result of statistical distribution of Na and Zr in the ZrO6 octahedra a nd ordered distribution of sodium atoms in the interstices of the channels. Formation of K2Zr(PO4)(2) and K5Zr(PO4)(3) phases with NZP structures is s hown to be possible.