AbstractDifferential thermal analysis (DTA) measurements were carried out in order to investigate thermal properties of model flux compositions of CdTe-CdCl2 with CdTeO3, the last recognized as a main oxidation product of CdTe. The composition of the flux was chosen to obtain larger quantity of residual flux phases for analyses and the presence of solid CdTe phase (about 20 mol%) at the fusion temperature 520 °C in a vacuum-closed isothermal quartz ampoule. Quantity of CdTeO3 constituted 20 mol % of the whole sample mass. DTA curves taken in the 300-700°C interval reveal considerable lowering of melting and solidification temperatures for the flux with addition of CdTeO3. The fused batches were vacuum annealed at 470 °C in a long narrow quartz tube for separation and deposition of volatile components CdCl2 and Te at the room temperature part of the tube. After vacuum annealing the residual CdTe phase on the batch with tellurite was coated with transparent platelike crystals morphologically typical to the CdTeO3, while oxide-free batch had no alien phases. In the flux, CdCl2 has a role of catalytic agent forming low melting point composition with native oxides and CdTe. After processing, CdCl2 can be separated by vacuum annealing.
Barium oxide as a modifier to stabilize the γ-Al2O3 structure