Ionothermal synthesis of β-NH4AlF4 and the determination by single crystal X-ray diffraction of its room temperature and low temperature phases
作者:Emily R. Parnham、Alex M.Z. Slawin、Russell E. Morris
DOI:10.1016/j.jssc.2006.09.024
日期:2007.1
beta-NH4AlF4 has been synthesised ionothermally using 1-ethyl-3-methylimidazolium hexafluorophosphate as solvent and template provider. beta-NH4AlF4 crystals were produced which were suitable for single crystal X-ray diffraction analysis. A phase transition occurs between room temperature (298 K) and low temperature (93 K) data collections. At 298 K the space group = I4/mcm (no. 140), alpha = 11.642(5), c = 12.661(5) angstrom, Z = 2 (10NH(4)AlF(4)), wR(F-2) = 0.1278, R(F) = 0.0453. At 93 K the space group = P4(2)/ncm (no. 138), alpha = 11.616(3), c = 12.677(3) angstrom, Z = 2 (10NH(4)AlF(4)), wR(F-2) = 0.1387, R(F) = 0.0443. The single crystal X-ray diffraction study of beta-NH4AlF4 shows the presence of two different polymorphs at low and room temperature, indicative of a phase transition. The [AlF4/2F2](-) layers are undisturbed except for a small tilting of the AlF6 octahedra in the c-axis direction. (c) 2006 Elsevier Inc. All rights reserved.