Effects of TiO2 doping and sintering temperature on electrical, mechanical and thermal properties of Al2O3 ceramics

The effects of TiO 2 content and sintering temperature on the electrical and mechanical properties of the alumina ceramics prepared via vacuum sintering were investigated. The sample comprises the phases of Al 2 O 3 , MgAl 2 O 4 , and Al 2 TiO 5 . Under vacuum sintering conditions, oxygen atoms in TiO 2 detach from the crystal lattice, forming quasi-free electrons, oxygen vacancies and Ti 3+ , thereby reducing the volume resistivity of alumina ceramics. XPS (X-ray photoelectron spectroscopy) analysis revealed that the increasing TiO 2 content facilitates the transformation of Ti 4+ to Ti 3+ , while elevated sintering temperatures further enhance Ti 3+ concentration, attributed to the enhanced lattice activity of TiO 2 . The increasing TiO 2 generated more Al 2 TiO 5 with Al 2 O 3 , which accumulated at grain boundaries, inhibiting grain growth through a pinning effect and forming more uniform and smaller grains, thereby enhancing mechanical property. Optimal comprehensive properties were achieved at a sintering temperature of 1500°C with 6 % TiO 2 content, demonstrating a density of 3.88 g/cm 3 , volume resistivity of 1.2×10 11 Ω·cm, dielectric strength of 3.6×10 6 V/m, hardness of 14.4 GPa, and thermal conductivity of 17 W/(m·K). The series of outstanding performances confirm that Al 2 O 3 ceramic with TiO 2 doping is an excellent candidate material in advanced semiconductor processing.