STRUCTURE AND VIBRATION-SPECTRA OF NEW PSEUDO-PYROPHOSPHATE NADYP2O7

A new phosphate with formula NaDyP2O7 was synthesized via solid-state reaction and characterized by X-ray powder diffraction (XRD), infrared and Raman spectra. Its XRD data, almost superimposing those of the te tragonal DyPO4, can be indexed into a tetragonal system with a = 6.916 (4) Angstrom, c = 6.048(5) Angstrom, space group 14(1)/amd(141) and Z = 3. The infrared and Raman spectra show two groups of vibrations: one stems from the DyPO4 lattice and the other possesses the characterist ics of NaPO3. No vibrations assigned to the P2O74- group were observed . Its unit-cell composition can be regarded as DyPO4 . NaPO3 with Z = 3. (C) 1997 Elsevier Science Ltd.