Dielectric Relaxations in Rutile TiO ₂

Abstract

Dielectric properties of high‐purity (4N degree) rutile TiO 2 ceramics were investigated over a wide temperature (100–1073 K) and frequency (20 Hz–10 MHz) ranges. X‐ray photoemission spectroscopy measurement revealed the sample possesses mixed‐valent states of Ti 3+ / Ti 4+ . Four thermally activated relaxations were observed. The lowest temperature relaxation (R1) features two Arrhenius segments with activation energy of 30 and 80 meV for the low‐ and high‐temperature segments, respectively. This relaxation was argued to be a polaron relaxation due to electrons hopping between Ti 3+ and Ti 4+ ions. The second relaxation (R2) appears around room temperature showing activation energy of 0.68 eV is believed to be a Maxwell‐Wagner relaxation. The high‐temperature relaxations R3 and R4 with activation energy of 0.84 and 1.26 eV were ascribed to the conduction process due to the hopping motions of singly and doubly charged oxygen vacancies, respectively.