Electrical properties of chromia-doped rutile (TiO₃)

Dielectric constants and AC resistivities of rutile (TiO2) doped with chromia (Cr2O3) have been measured as a function of frequency in the range 30 Hz to 60 kHz over the temperature range 201 to 333K. Measurements of DC resistivities in the temperature region 77 to 273K have also been made. The specimens were prepared by heating single rutile crystals on Cr2O3 pellets, at 1573K, in air for various heating times. The dielectric constants depend markedly on the frequency of measurement and also have considerably broader frequency ranges of dispersions than are predicted by Debye's theorem. The dielectric constant at low frequencies (30-100 Hz) increases as the sample preparation heating time is extended. DC resistivities obtained at 273K also increase with prolonged heating time. These results have been discussed in terms of crystallographic shear planes which are expected to form in this system.