Synthesis, crystal structure and vibrational spectra characterization of (MLa)-La-I(PO3)(4) (M-I = Na, Ag)

摘要

The single crystals of lanthanum metaphosphate MLa(PO3)(4) (M = Na, Ag) have been synthesized and studied by a combination of X-ray crystal diffraction and vibrational spectroscopy. The sodium and silver compounds crystallize in the same monoclinic P2(1/)n space group (C(2)(5)h factor group) with the following respective unit cell dimensions:.a 7.255(2), b = 13.186(3), c = 10.076(2) A, beta = 90.40(2)degrees, V = 963.0(4)angstrom(3), Z = 4 and a = 7.300(5), b = 13.211(9), c = 10.079(7) angstrom, beta = 90.47(4)degrees, V = 972.09(12) angstrom(3), Z = 4. This three-dimensional framework is built of twisted zig-zag chains running along a direction and made up Of PO4 tetrahedra sharing two corners, connected to the LaO8 and NaO7 or AgO7 Polyhedra by common oxygen atoms to the chains. The infrared and Raman vibrational spectra have been investigated. A group factor analysis leads to the determination of internal modes of (PO3)(-) anion in the phosphate chain. (c) 2005 Elsevier Inc. All rights reserved.