Evolved gas analysis during sintering of barium titanate

The gases evolved during the sintering of BaTiO3 have been examined with a combined dilatometer and mass spectrometer (CDMS) apparatus. The CDMS acquires multiple mass/charge ratios in real time while simultaneously recording dilatometry data. To identify the chemical composition of the numerous recorded mass/charge ratios, cracking patterns, isotopic abundances and decomposition reactions from model compounds (BaCO3, BaSO4) were used. Three primary regions of gas evolution were identified. During the heating ramp and into the hold period at 1350°C, CO2 appears, and below approximately 500°C, this may arise from adsorbed or surface CO2. Sulphur dioxide was also observed, and its evolution occurred directly after the majority of the CO2 appeared and immediately preceded the onset of sintering. Above 1200°C, CO2 is the primary species observed in the gas phase. The implications of the high temperature chemistry on sintering and on microstructural development are discussed.