Decomposition Behavior of Ternary Compounds in the Al–Te–O System and Phase Equilibrium of Al2O3–TeO2 System Below 920 °C in Air.

Ternary compounds in the Al–Te–O system have been considered as potential materials for Low-Temperature Co-fired Ceramics preparation. Two ternary compounds, Al₂TeO₆ and Al₂Te₂O₇, have been found in the Al–Te–O system under 920 °C in air. The decomposition behavior of these two compounds has been studied with Thermogravimetric Analysis-Differential Scanning Calorimetry (TGA-DSC) and equilibration experiments. Phase equilibrium of the Al₂O₃–TeO₂ system has also been experimentally investigated at ambient atmosphere, and corresponding phase diagram has been derived. Obtained results showed that Al₂Te₂O₇, could only be found when TeO₂ was 66.7-70.0 mol pct and temperature was at 590 °C to 610 °C. Al₂TeO₆ decomposed into Al₂O₃, TeO₂(g), and O₂(g) when temperature was above 920 °C. Al₂Te₂O₇ converted into Al₂TeO₆ at 620 ± 2 °C, and then followed the decomposition path of Al₂TeO₆. In phase equilibrium study, when the initial sample started from the Al₂O₃–Al₂TeO₆ region, Al₂TeO₆ and Al₂O₃ were found in quenched samples at the temperature range of 500 °C to 915 °C. When the initial sample started from the Al₂TeO₆–TeO₂ phase region, two solid phases, Al₂TeO₆ and TeO₂, could be found in samples prepared under 725 ± 2 °C. When the temperature was above 730 ± 2 °C, there were Al₂TeO₆ and one oxide liquid phase. In the Al₂Te₂O₇–TeO₂ region, all equilibrated samples had Al₂Te₂O₇ and TeO₂. [ABSTRACT FROM AUTHOR]