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Alluaudite-like Structure of the Complex Arsenate NaCaCdMg2(AsO4)3

✍ Scribed by S. Khorari; A. Rulmont; P. Tarte; G. Miehe; D. Antenucci; B. Gilbert

Publisher
Elsevier Science
Year
1997
Tongue
English
Weight
279 KB
Volume
131
Category
Article
ISSN
0022-4596

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✦ Synopsis

The existence of a continuous series of solid solutions NaCaCdMg 2 [(PO 4 ) 1؊x (AsO 4 ) x ] 3 (04x41) suggests an alluaudite-like structure of the arsenate NaCaCdMg 2 (AsO 4 ) 3 . This is definitely confirmed by a Rietveld analysis of its X-ray powder diffractogram. The crystal cell is monoclinic, space group C2/c, with a ‫؍‬ 12.2363(1), b ‫؍‬ 12.9869(1), c ‫؍‬ 6.7742(1) A s , ‫؍‬ 113.7985(3)Β°. The Mg 2Ψ‰ cations are essentially located on the M(2) sites of the alluaudite structure, but the distribution of the Na Ψ‰ , Ca 2Ψ‰ , and Cd 2Ψ‰ cations over the M(1), X(1), and X(2) sites is more or less disordered. The existence of a partial disorder in the cation distribution is supported by some diffuseness of the Raman and IR spectra.

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