An easy approach to realize high thermal conductivity similar to single crystal and low hygroscopicity in magnesia sintered at low temperature

Magnesia (MgO) has a high thermal conductivity (40–60 W m−1K−1) which is required in a heat-dissipation material. However, the sintering temperature of MgO is very high (approximately 2000 °C), and it significantly reacts with moisture in the air. In this study, it is described that the sintering temperature of MgO is easily lowered by the small amount of B2O3. B2O3-added MgO (B-MgO) sintered at 1300–1400 °C showed a high density of >3.5 g cm−1 and a high thermal conductivity of 52–54 W m−1K−1, which is similar to 50–55 W m−1K−1 of a single-crystal MgO. The high thermal conductivity of B-MgO which is similar to that of a single-crystal MgO can be explained by the difference of a point defect. In particular, it is expected that B-MgO can be well-mixed with a polymer to prepare thermal interface materials (TIM), since it does not react with moisture in the air.