Crystal structure and thermal behaviour of Er-2(SeO4)(3)center dot 8H(2)

摘要

Single crystals of Er-2(SeO4)(3) (.) 8H(2)O were obtained by dissolving Er2O3 in selenic acid. The selenate crystallizes in the monoclinic space group C2/c (Z = 4, a = 1372.8(2), b = 687.51(7), c = 1860.2(3) pm, beta = 101.85(2)degrees, R-all = 0.0518) and contains the Er3+ ions in eightfold coordination of oxygen atoms that belong to two crystallographically different SeO42- ions and to four H2O molecules. According to DTA/TG measurements and temperature dependent powder diffraction data, Er-2(SeO4)(3) (.) 8H(2)O decomposes in several steps yielding finally Er2O3. Er-2(SeO4)(3) and Er-2(SeO3)(3) could be identified as intermediates, and for Er-2(SeO4)(3) a phase transition was detected.