Abstract: | In a study of the solid-state reactions in the ternary systems TeO2? MoO3? MoO2 and TeO2? MoO3? Te, approximately 70 selected compositions were sintered at 550°C to attain equilibrium conditions, and solid-state equilibrium relations were characterized by x-ray diffraction. In a large composition range, the interaction of TeO2 and MoO3 with the reducing agents MoO2 or Te leads to the reduced ternary oxide TeMo4O13 (m. p. 748°C), in addition to Te2MoO7, Te and (intermediate) molybdenum oxides. The compatibility relations for the binary systems TeO2? MoO2 and MoO3? Te are presented for the first time. In the TeO2? MoO2 system, three-phase regions are found: (Te2MoO7? TeO2? Te) on the TeO2? and (TeMo4O13? MoO2? Te) on the MoO2-rich sides with (TeMo4O13? Te2MoO7? Te) in the intermediate region. In the MoO3? Te system, three-phase regions (TeMo4O13? MoO2? Te), (TeMo4O13? Mo4O11? MoO2) and (TeMo4O13? MoO3? Mo4O11) were detected. TeMo4O13 presents two allotropic forms (α′ for T < 450°C, α for T > 450°C). Both structures have been characterized by I.R. and optical reflectance spectroscopy. Unit cell dimensions are also given. |