Effects of sintering processes on second-phase grain morphology of ITO ceramics and grain growth

Due to the importance of grain morphology and grain size of ITO ceramics on the properties of ITO films, 12 ITO ceramics were sintered at different sintering process parameters in order to investigate the effects of heating rate, singtering temperature, holding time, cooling rate and oxygen flow velocity on the second-phase grain morphology and grain growth of ITO ceramics by SEM, XRD, BSE and EPMA et al.. The results show that the high quality ITO ceramics can be achieved with the heating rate of 120 °C/h, the sintering temperature of 1580 °C, the holding time of 5 h, the cooling rate of 240 °C/h and oxygen flow velocity of 10 L/min. It can also conclude that the change of the second-phase grain morphology is only relevant to the sintering temperature. Meanwhile, the grain growth kinetics was first introduced to analyze the grain growth mechanism and calculate the corresponding diffusion datas (n = 7, k = 9.282 × 1022 nm3/min, Q = 405.588 KJ/mol). In addition, the mass transport mechanism leading to the considerable grain coarsening and the change of second-phase grain morphology is evaporation–condensation followed by the increased solubility of SnO2 in In2O3.