Enhanced thermal conductivity and sinterability of magnesia via nano-powder addition: Control of pore formation and densification

MgO ceramics are promising candidates for high thermal conductivity applications in next-generation electronics. However, their practical application is hindered by the extremely high sintering temperature and hygroscopic instability of MgO. In this study, dense MgO ceramics were achieved through the combined use of multi-scale micro/nano MgO powders and TiO 2 /Nb 2 O 5 additives under spark plasma sintering (SPS). Notably, 5 wt.% nano-MgO combined with additives enabled densification at 1200 °C with conductivities above 41 W/m·K, demonstrating the feasibility of low-temperature processing. Finally, SPS of the optimized composition achieved nearly full density and 60 W/m·K, underscoring the synergistic effect of multi-scale mixing, additives, and applied pressure, and advancing next‑gen MgO thermal‑management materials due to improved grain-boundary connectivity and heat transport. This work provides new insights into practical route for cost-effective fabrication of high-conductivity MgO ceramics at low temperature. • The addition of nano-sized MgO to micro-sized MgO enhanced densification and thermal conductivity. • The addition of nano-sized MgO and sintering additives led to a thermal conductivity of 41 W/m·K, even at 1200 °C. • Pressure-assisted sintering minimized residual pores, yielding nearly full density and 60 W/m·K.