Influence of grain size on the thermal conductivity of tin oxide ceramics

Measurement of the thermal diffusivity by the laser flash technique has been used to evaluate thermal conductivity values between 20°C and 900°C for tin oxide ceramics. By using MnO2 as a sintering additive, strong variation of the microstructure in terms of porosity and average grain size was achieved in the samples. For dense ceramics, larger average grain size yielded a significant increase in the room temperature thermal conductivity. This could be attributed to a reduction of the number of grain boundaries in the heat flow path. The grain boundary interfacial resistance was consequently estimated at 4.1×10−8 m2 KW−1. Data concerning the effects of additive amount, pore content, and temperature are also reported.