LAYERED ACID ARSENATES ALPHA-M(HASO4)(2)CENTER-DOT-H2O (M = TI, SN, PB) - SYNTHESIS OPTIMIZATION AND CRYSTAL-STRUCTURES

The syntheses of alpha-M(HAsO4)2 . H2O (M = Ti, Sn and Pb) have been o ptimized to prepare crystalline single phase materials. The crystal st ructures of M = Sn, Pb have been refined using X-ray powder diffractio n data by the Rietveld method. A combined X-ray and neutron powder dat a refinement for M = Ti has allowed to obtain a very detailed picture of the structure including the hydrogen-bonding network. The results h ave been compared with those of the phosphates analogs. In addition, d etailed characterization of the samples has been carried out by IR spe ctroscopy, thermal analysis and powder thermodiffractometry. (C) 1998 Elsevier Science B.V. All rights reserved.