Phase equilibrium in The TeO2Cu2O System

Phase equilibrium in the TeO2Cu2O system was determined in air at atmospheric pressure. Differential thermal analysis (DTA), X-ray powder diffraction and optical microscopy were used to identify the phase transitions. Two congruently melting compounds Te3Cu2O7 and TeCu2O3 were obtained. They possess monoclinic and hexagonal symmetry respectively. The morphology, optical properties and indexed powder pattern up to 1.3 A are submitted for these compounds. Experiments realized by the DTA indicated the existence of an oxidation process with beginning and rate dependent on the composition. The glass formation limits determined for 2 g and 10 g tellurite glass melts correlate with the invariant points in the system.