Tuning dielectric properties in a rutile TiO2 system via synergistic design of surface structure and microstructure

Abstract

Colossal permittivity material is a promising candidate for miniaturizing sensors, capacitors, and energy storage devices. As critical systems, TiO2-based materials exhibit high permittivity. However, the contradiction among their dielectric constant, dielectric loss, and temperature stability impedes the use of TiO2-based materials in electronic devices. By using a synergistic design of surface structure and microstructure, a series of Eu + Ta codoped TiO2 ceramics with excellent dielectric properties is successfully prepared. The ceramic sample (ET-1) has a high permittivity (εr = 1.40 × 105), a low dielectric loss (tanδ = 0.019, at 25℃ and 1 kHz), and an excellent temperature stability (Δεr/ε25 ≤ ±5% (−70 °C–250 °C)). Furthermore, the physical mechanism underlying the colossal permittivity behavior is systematically investigated using experimental characterizations and first-principles calculations. The results show that internal electron redistribution and surface charge accumulation/depletion efficiently regulate the dielectric performance of codoped ceramics.