Alluaudite-Like Structure of the Arsenate Na3In2(AsO4)3

✍ Scribed by S. Khorari; A. Rulmont; P. Tarte

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 287 KB
• Volume: 134
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7526

✦ Synopsis

The arsenate Na3In2(AsO4)3 has been synthesized and investigated by X-ray diffraction and vibrational spectroscopy. According to a Rietveld analysis, it is monoclinic, space group C2/c, Z ‫؍‬ 4, with a ‫؍‬ 12.6025 (1), b ‫؍‬ 13.1699 (1), c ‫؍‬ 6.8335 (1) A s , ‫2247.311؍‬ (5). It has an alluaudite-like structure, with the three Na ؉ cations located on the three large sites X(2), X(1), and M(1), and the two In 3؉ cations on the M(2) sites of this structure. This is a new type of chemical formula (free from bivalent cations and with a full occupancy of the X(2), X(1), and M(1) sites by sodium ions) for an alluaudite-like structure. The Raman and infrared spectra exhibit a great number of sharp bands, as expected from the low symmetry and from the ordered distribution of the cations, but this complexity precludes a detailed assignment of the bands. Structural analogies or differences with other alluaudite-like compounds are briefly discussed.