The Fe2+/Fe3+ ratio in natural and heat-treated iron-rich eudialytesстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The structures of natural iron-rich eudialyte (specimen 3458 from the Khibiny massif, the Kola Peninsula) and two heat-treated samples of this mineral calcined at 700 and 800A degrees C were determined by X-ray diffraction. The trigonal unit-cell parameters (sp. gr. R3m) are as follows: a = 14.2645(1) , c = 29.9635(5) ; a = 14.1307(1) , c = 30.1229(3) ; a = 14.1921(2) , c = 30.2417(5) , respectively. It was found that Fe3+ ions in the calcined eudialytes, as well as impurities in the starting specimen, occupy the square-pyramidal Fe3+(V) sites, whereas Fe2+ ions are in the planar-tetragonal Fe2+(IV) sites.