New ordered phases of slightly reduced rutile and their sharp dielectric absorptions at low temperature

The temperature dependence of the complex dielectric constant of single-crystal rutile has been studied at different frequencies and as a function of reduction. The results suggest the existence of two new ordered phases in slightly reduced rutile. Sharp dielectric absorptions have been observed in these phases. This is attributed to the hopping of low-mobility charge carriers between two ion sites. The nature of the charge carriers introduced by reduction is discussed. It is proposed that the room-temperature conductivity alone may not characterize the state of a slightly reduced rutile sample.