Magnetic, optical, and electron transport properties of n-type CeO2: Small polarons versus Anderson localization MAGNETIC, OPTICAL, and ELECTRON TRANSPORT ... TARAS KOLODIAZHNYI et al.

Kolodiazhnyi, Taras; Charoonsuk, Thitirat; Seo, Yu Seong; Chang, Suyong; Vittayakorn, Naratip; Hwang, Jungseek

doi:10.1103/PhysRevB.95.045203

Magnetic, optical, and electron transport properties of n-type CeO2: Small polarons versus Anderson localization MAGNETIC, OPTICAL, and ELECTRON TRANSPORT ... TARAS KOLODIAZHNYI et al.

Author(s)

Kolodiazhnyi, Taras

Charoonsuk, Thitirat

Seo, Yu Seong

Chang, Suyong

Vittayakorn, Naratip

Hwang, Jungseek

Date Issued

January 11, 2017

Type

Article

DOI

10.1103/PhysRevB.95.045203

Abstract

We report magnetic susceptibility, electrical conductivity and optical absorption of Ce1-xMxO2 where M = Nb,Ta and 0≤x≤0.03. The dc conductivity follows a simple thermally activated Arrhenius-type behavior in the T=70-700 K range with a change in slope at T∗≈155 K. The high-temperature activation energy shows gradual increase from ≈170 to 220 meV as the dopant concentration increases. The activation energy of the low-temperature conductivity shows a broad minimum of ≈77 meV at x≈0.01. Electron transport and localization mechanisms are analyzed in the framework of the Holstein small polaron, Anderson localization, and Jahn-Teller distortion models. The fit to the small polaron mobility is dramatically improved when, instead of the longitudinal phonons, the transverse optical phonons are considered in the phonon-assisted electron transport. This serves as an indirect evidence of a strong 4f1 orbital interaction with the oxygen ligands, similar to the case of PrO2. Based on comparison of the experimental data to the models, it is proposed that the defect-induced random electric fields make the dominant contribution to the electron localization in donor-doped ceria.

Citation

Physical Review B, 95(4), 2017