Intrinsic Enhancement of Dielectric Permittivity in (Nb + In) co-doped TiO2 single crystals

TL;DR

This paper demonstrates that co-doped TiO2 single crystals exhibit significantly enhanced dielectric permittivity at low temperatures due to intrinsic defect mechanisms, offering new avenues for high-permittivity dielectric materials.

Contribution

It reveals that intrinsic defect engineering can boost permittivity in TiO2, independent of extrinsic carrier effects, at low temperatures.

Findings

Permittivity quadruples compared to pure TiO2.

Enhancement is intrinsic, observed at low temperatures.

Electron-pinned defect-dipoles contribute to dielectric response.

Abstract

The development of dielectric materials with colossal permittivity is important for the miniaturization of electronic devices and fabrication of high-density energy-storage devices. The electron-pinned defect-dipoles has been recently proposed to boost the permittivity of (Nb + In) co-doped TiO2 to 105. However, the follow-up studies suggest an extrinsic contribution to the colossal permittivity from thermally excited carriers. Herein, we demonstrate a marked enhancement in the permittivity of (Nb + In) co-doped TiO2 single crystals at sufficiently low temperatures such that the thermally excited carriers are frozen out and exert no influence on the dielectric response. The results indicate that the permittivity attains quadruple of that for pure TiO2. This finding suggests that the electron-pinned defect-dipoles add an extra dielectric response to that of the TiO2 host matrix. The results offer a novel approach for the development of functional dielectric materials with large permittivity by engineering complex defects into bulk materials.