Synthesis and Study of New Compounds ( MI) ( NIV) 2(PO 4) 3 with Nasicon-like Structure ( M = Ag, Cu; N = Ge, Hf, Sn, Ti, Zr)

Compounds ( M I) ( N IV) 2(PO 4) 3 ( M = Ag, Cu; N = Ge, Hf, Sn, Ti, Zr) have been synthesized using solid-state reactions. Attempts to synthesize CuGe 2(PO 4) 3 did not succeed. All other compounds have Nasicon-like structure (space group R3̄ c ). AgGe 2(PO 4) 3, AgHf 2(PO 4) 3, CuSn 2(PO 4) 3, and CuHf 2(PO 4) 3 are described for the first time. Cell parameters, vibrational spectra, and ionic conductivities are given. Silver compounds have higher conductivities than, but the same spectral behavior as, corresponding sodium compounds. The spectra of copper compounds show significant differences, perhaps because of peculiar localization of copper in the structure.