Evidence for Vogel Fulcher behavior of the 50K-relaxation in (Tm+Ta) co-doped TiO2 ceramics

Abstract

There is still no consensus about the relaxation behavior of the so-called 50[Formula: see text]K-relaxation in acceptor and donor co-doped TiO2 system. Herein, the relaxation behavior of the 50[Formula: see text]K-relaxation was investigated in (Tm[Formula: see text][Formula: see text][Formula: see text]Ta) co-doped rutile TiO2 ceramics. Dielectric properties of the sample were studied in the temperature range of 2–300[Formula: see text]K under 100 frequencies in the range of 102–106[Formula: see text]Hz. The sample shows a pronounced 50[Formula: see text]K-relaxation. Various relaxation behaviors of Arrhenius, Mott’s variable range hopping, and Vogel Fulcher laws were tried to describe the relaxation. The result indisputably evidences that the 50[Formula: see text]K-relaxation follows the Vogel Fulcher law. This work provides a heuristic hint to understand the fundamental physics underlying the colossal permittivity behavior in the acceptor and donor co-doped TiO2 ceramics system.