Dielectric relaxation in hollandites and rutile

Abstract

The dielectric properties of several Ba hollandites Ba_x,X_nx,Ti_8-nx,O₁₆ (X = Mg, A1 or Ga) have been measured and the features which are common to the relaxation processes in this range of hollandites have been established. It is concluded that the dielectric absorption in these compounds is due to a Maxwell-Wagner mechanism and the nature of the conducting regions is discussed. An absorption process with a low activation energy was detected in some samples but this has been shown to be due to TiO₂, impurity present as a second phase. The dielectric absorption of several TiO₂, samples has been investigated. It is suggested that the absorption in slightly reduced TiO₂, is due to conductivity in the shear planes, the predominant defects in TiO_2-x.