Static Dielectric Constant of Rutile (TiO2), 1.6-1060°K

Abstract

The static dielectric constant $\epsilon$ of rutile has been measured as a function of temperature from 1.6 to 1060°K. Rutile does not appear to be ferroelectric or antiferroelectric in this temperature range. At low temperatures, $\epsilon$ approaches a limiting value of 257 in the $c$ direction and 111 in the $a$ direction. ${\epsilon }_{300°\mathrm{K}}=170\mathrm{} \mathrm{and} 86$, respectively, and ${\epsilon }_{1000°\mathrm{K}}=97\mathrm{} \mathrm{and} 58$. The ionic polarizability of titanium is calculated using the previously derived Lorentz correction in the rutile structure. The polarizability at all temperatures is very close to the critical value for a ferroelectric polarization catastrophe. The temperature variation of the ionic polarizability is explained qualitatively on the basis of other properties of the crystal.