Rietveld refinement and spectroscopic studies of sodium lead fluoroapatite lacunaire synthesized by hydrothermal method

详细信息	查看全文 | 推荐本文 |

• 作者：M. Toumi ; T. Mhiri
• 关键词：A. Inorganic compounds ; B. Crystal structure ; C. X-ray diffraction ; C. Infrared spectroscopy ; C. Nuclear magnetic resonance (NMR) ; C. Raman spectroscopy
• 刊名：Materials Research Bulletin
• 出版年：2008
• 期刊代码：60_00255408
• 类别：ms
• 出版时间：3 June 2008
• 卷：43
• 期：6
• 页码：1346-1354
• 文件大小：386 K

摘要

The structure of NaPb₉(PO₄)₆F(H₂O)_0.33, isostructural with apatite, was determined by X-ray powder diffraction methods and the result of Rietveld refinement is P6₃/m, a = 9.76396(8) Å and c = 7.27520(9) Å. The final refinement led to R_F = 5.4%, R_B = 6.6%. In the tunnel, the water molecule (O_w) and F⁻ ions appear to be located in 2b and 4e sites, with occupancies of 0.028(6) and 0.075(8), respectively. In the M(1) and M(2) sites the occupancies of Pb and Na are 0.282(3)/0.051(3) and 0.467(5)/0.033(5), respectively. The formula assigned to the compound is [Pb_3.38(4)Na_0.62(4)](1)[Pb_5.60(6)Na_0.40(6)](2)(PO₄)₆F_0.90(10)(H₂O)_0.33(7)%a1;_0.77(17), where %a1; = vacancy. The assignment of the observed frequencies in the Raman and infrared spectra is discussed on the basis of a unit-cell group analysis and by comparison with fluor and chloroapatite analogs. The result of ³¹P and ²³Na magic angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopies confirmed the structural results.