Charge transfer drives anomalous phase transition in ceria

He Zhu, Chao Yang, Qiang Li, Yang Ren, Joerg C. Neuefeind, Lin Gu, Huibiao Liu, Longlong Fan, Jun Chen, Jinxia Deng, Na Wang, Jiawang Hong, Xianran Xing

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Ceria has conventionally been thought to have a cubic fluorite structure with stable geometric and electronic properties over a wide temperature range. Here we report a reversible tetragonal (P42/nmc) to cubic (Fm-3m) phase transition in nanosized ceria, which triggers negative thermal expansion in the temperature range of −25 °C–75 °C. Local structure investigations using neutron pair distribution function and Raman scatterings reveal that the tetragonal phase involves a continuous displacement of O2− anions along the fourfold axis, while the first-principles calculations clearly show oxygen vacancies play a pivotal role in stabilizing the tetragonal ceria. Further experiments provide evidence of a charge transfer between oxygen vacancies and 4f orbitals in ceria, which is inferred to be the mechanism behind this anomalous phase transition.

Original languageEnglish
Article number5063
JournalNature Communications
Volume9
Issue number1
DOIs
StatePublished - Dec 1 2018

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