UNKNOWN THERMAL PROPERTIES OF ZnSb2O6 AND Zn7Sb2O12 COMPOUNDS Reactivity of α-Sb2O4 with ZnO on heating in air

The investigations by XRD, DTA/TG and IR methods show that two compounds: ZnSb2O6 and Zn7Sb2O12 are formed in the ZnO-alpha-Sb2O4, system in air. Oxygen contained in the air participates in the synthesis of these compounds. ZnSb2O6 was observed as an intermediate phase, during the Zn7Sb2O12 synthesis. The temperature of the beta ->alpha-Zn7Sb2O12 transition was fixed at 1225 +/- 10 degrees C. The mechanisms of the reactions of ZnSb2O6 and Zn7Sb2O12 thermal decomposition have been proposed. The IR studies of alpha and beta-Zn7Sb2O12 have initially indicated that the structures of both polymorphous forms differ in the reciprocal connection of the SbO6 and ZnO6 octahedra and the ZnO4 tetrahedra.