Densification behaviour and sintering mechanisms of Cu- or Co-doped SnO2: A comparative study

Abstract Compared with the CuO–SnO 2 system, there is a lack of experimental evidence of a eutectic liquid phase in the CoO–SnO 2 system. It is therefore believed that the densification behaviour and sintering mechanisms of the two systems are completely different. However, our present study clearly demonstrated that the Co- and Cu-doped SnO 2 ceramics exhibited a similar densification behaviour. The 1 wt.% Cu- or Co-doped SnO 2 ceramics could reach over 95% relative density when sintered to 1250 °C with a heating rate of 5 °C min −1 . It was found that both CoO 4/3 - and CuO-doped SnO 2 follow the same mass transport mechanism – viscous flow sintering during early-stage sintering. This was verified with the classic isothermal and constant-heating-rate models, as well as Frenkel’s viscous flow theory. The viscous flow mechanism dominated densification up to ∼73 and ∼78% relative density with the apparent activation energies of 362 and 440 kJ mol −1 for Co and Cu doping cases, respectively.