The effect of Li-salt additions on the densification of tin oxide

Sintering of pure SnO₂ to high densities is difficult due to its high vapor pressure, and hence, additives are typically used to enhance densification. In this study, the effects of two lithium compounds, LiF and LiNO₃, on the densification behavior of SnO₂ were evaluated. While LiF resulted in only a modest improvement in densification, LiNO₃ additions resulted in densities of ≥ 95% theoretical at 1500 °C in air. Thermal, x-ray, and SEM/TEM microstructural analyses indicated no liquid phase formation. From these studies we attribute the enhanced sintering behavior to the ionic-compensation of Li⁺ as an acceptor dopant, i.e., 3[Li‴_sn] = 2[V_oö], which in turn increased the diffusivity of oxygen.