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 degrees 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 degrees C to 610 degrees C. Al2TeO6 decomposed into Al2O3, TeO2(g), and O-2(g) when temperature was above 920 degrees C. Al2Te2O7 converted into Al2TeO6 at 620 +/- 2 degrees 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 degrees C to 915 degrees 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 degrees C. When the temperature was above 730 +/- 2 degrees C, there were Al2TeO6 and one oxide liquid phase. In the Al2Te2O7-TeO2 region, all equilibrated samples had Al2Te2O7 and TeO2.

Automated summary

Two ternary compounds, Al2TeO6 and Al2Te2O7, have been found in the Al-Te-O system, and their decomposition behavior has been studied. The phase equilibrium of the Al2O3-TeO2 system has also been experimentally investigated.