Effect of sintering atmosphere and annealing temperature on electrical and optical properties of TiO2 ceramic

TiO2 ceramics possess excellent microwave dielectric properties, but defects have a great influence on the dielectric properties of materials. Compared with the TiO2 sintered under air(Resistivity = 10(9) Omega.m, epsilon(r) approximate to 78.62, 3.2 GHz), in N-2 atmosphere, the TiO2 ceramic has a resistivity of 100 Omega.m, epsilon(r) approximate to 10(5) (1 kHz), and the microwave performance degenerates. It proves that the oxygen vacancy defect formed in the anoxic environment is the main reason of the change of electrical properties. Based on the above analysis, TiO2 (N-2) ceramics are annealed under air at different temperatures. As the annealing temperature increases to 1200 degrees C, the resistivity of TiO2 returns to 10(9) Omega.m, epsilon(r) approximate to 100(around 3 GHz), and the forbidden band width gradually increases to 2.86 eV from 1.42 eV, confirming the annealing treatment method can reduce the concentration of material defects, so that the electrical properties of TiO2 ceramics are better restored.