Dielectric Properties of Single-Crystal Nonstoichiometric Rutile (TiO2)

Abstract

The dielectric constant ε′ and dielectric loss ε″ have been determined from 30 to 300 000 cps in the a and c crystal directions for nonstoichiometric compositions of rutile with dc resistivities from 10⁴ to 10¹³ Ω‐cm. Measurements with asymmetrical electrodes and geometrical variations indicate that the properties are primarily a bulk effect. Quasi‐ferroelectric effects were observed at field gradients greater than 500 V/cm and at frequencies above 0.5 cps. It is suggested that the dielectric properties of rutile can be explained by an artificial dielectric model consisting of conducting needles of heterogeneously distributed oxygen vacancies embedded in an insulating medium.