SPINEL-LIKE SOLID-SOLUTIONS AND HYBRID PHASES IN THE FES-CR2S3-SNS2 SYSTEM

A portion of the FeS-Cr2S3-SnS2 system around the spinel FeCr2S4 was s tudied by x-ray diffraction and Mossbauer effect measurements. We reve aled a wide range of cation-deficient spinel solid solutions Fe-1-x[Cr 2-2x-2yFySn2x+y]S-4 (0 less than or equal to x less than or equal to 0 .33, 0 less than or equal to y less than or equal to 0.33, y less than or equal to x) and ranges of solid solutions based on the hybrid phas es S-186 (Fe1.63Cr0.38Sn0.91S4-Fe1.75Cr0.12Sn1.04S4) and S-190(I, II) (Fe1.03CT1.81Sn0.13S4-Fe1.62Cr0.63Sn0.72S4) cation-deficient relative to spinel stoichiometry. In all cases, the tetrahedral sites are occup ied to some extent by Fe2+ ions only, whereas Sn4+ ions occupy only oc tahedral sites. In the hybrid phases S-1.86(Fe1.72CT0.19Sn1.0S4) and S -190(I-Fe1.53CT0.81Sn0.63S4, II-Fe1.03CT1.81Sn0.13S4), the nonspinel o ctahedral sites are only occupied by Sn4+ ions, while the spinel sites (atacamite framework) are randomly occupied by Fe2+, Cr3+, and Sn4+. The results of the present work were used to map out the Gibbs-Roozebo om triangle demonstrating possible phase relationships in the system u nder study at T similar or equal to 1000 K.