Decomposition behaviors of ternary compounds in the Mg-Te-O system at various atmospheric conditions

Thermodynamic studies of the Mg-Te-O system have significant importance in improving Te recovery from pyrometallurgical processes and materials preparation in related fields. Ternary compounds, Mg 3 TeO 6 , Mg 2 Te 3 O 8 , MgTe 2 O 5 and MgTe 6 O 13 , in the Mg-Te-O system have been synthesized in the present study, and their decomposition behaviors at various atmospheric conditions have been experimentally studied with the TGA-DSC technique. Obtained results showed that: 1) Mg 3 TeO 6 started to decompose to MgO , TeO 2 , and O 2 at 1255.9 °C in the carrying gas of 20% O 2 - 80% Ar, and the initial decomposition temperature decreased along with decreasing oxygen concentration in the gas; 2) Mg 2 Te 3 O 8 decomposed to MgO and TeO 2 , and when the O 2 was rich in the gas, Mg 3 TeO 6 was also found in the product. The initial decomposition temperature of Mg 2 Te 3 O 8 was 832.1 °C, 839.2 °C, and 839.9 °C, when the O 2 concentration in the carrying gas was 20%, 0.1%, and 0.0001%, respectively; 3) The decomposition products of MgTe 2 O 5 were same with that of Mg 2 Te 3 O 8 , and its initial decomposition temperature decreased along with decreasing the O 2 concentration in the gas; 4) MgTe 6 O 13 decomposed to MgTe 2 O 5 and TeO 2 around 700 °C, and the initial decomposition temperature decreased with decreasing O 2 concentration in the gas. Along with increasing temperature, MgTe 2 O 5 converted to Mg 3 TeO 6 through oxidation reactions, and Mg 3 TeO 6 decomposed at elevated temperatures.