Crystal structure and spectroscopic studies of Na2Pb 8(PO4)6

Abstract

The structure of sodium lead apatite Na2Pb8(PO 4)6 has been determined using single-crystal X-ray diffraction. Crystal data are: hexagonal, space group P63/m, Z = 1, a = 972.1(4) pm, c = 718.6(5) pm, V = 588.1(5) 106 pm3, and R = 0.038. The result of charge distribution analysis confirmed the structural hypotheses. In the Raman spectrum, the two bands observed at 935 cm-1 and at 966 cm-1, have been attributed to the Ag-E 2g splitting, in the hexagonal C6h symmetry, of the nondegenerate symmetric stretching ν1(PO4). Translational modes of Pb2+ have been identified at 44, 53, 56, 76 and 78 cm-1. The results of 31P and 23Na magic angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopies confirmed the structural hypotheses. ©2008 The Ceramic Society of Japan. All rights reserved.