The Dielectric Properties of the Rutile Form of TiO2

Three specimens of rutile were prepared and the dielectric properties studied over a range of frequency and temperature. A dielectric constant of approximately 100 was found which remained substantially constant through the highest radiofrequencies, falling off only in the infra-red region. The dielectric losses are low, particularly at the higher frequencies. The dielectric constant decreases with increasing temperature, having an average temperature coefficient of −8.2×10−4/°C. An exponential relationship between conductivity and the reciprocal of the absolute temperature holds for rutile in the higher temperature region. Mixtures of rutile powder with other dielectric materials obey a logarithmic mixture formula. Two mechanisms which have been proposed to explain the high dielectric constant of rutile are discussed. A simple mechanism based on the Clausius-Mosotti equation is described.