A comparative study of spark plasma and conventional sintering of undoped SnO2 sputtering targets

Abstract

SnO2 ceramics were fabricated by spark plasma sintering (SPS) and conventional (pressureless) sintering techniques using undoped submicron SnO2 powders. The effect of sintering temperature and dwell time on the densification behavior, phase evolution, and microstructural development of sintered ceramics were investigated. The relative density of SPSed ceramics increased when dwell time was raised from 1 to 10 min at 950 °C. However, full densification was prevented by the decomposition of SnO2 to Sn. The decomposition started after ∼10 min at 950 °C. In parallel to these observations, as sintering temperature increases, the elemental Sn in agglomerated form increases. On the other hand, the relative densities of conventionally sintered ceramics (at 1200°C-1400 °C) were relatively low (i.e., 63% relative density), and abnormal grain growth was observed due to the shift in sintering mechanisms to evaporation-condensation as a dominant mechanism. Since the undoped SnO2 ceramics, SPSed at 950 °C for 5 min under 30 MPa exhibit 93% relative density, high chemical purity, homogeneous grain size distribution, and smaller average grain size, they demonstrate great potential as sputtering targets for the production of high-quality thin film gas sensors.