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Charge transfer drives anomalous phase transition in ceria.

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 O^2- 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.

SUBMITTER: Zhu H

PROVIDER: S-EPMC6265291 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Charge transfer drives anomalous phase transition in ceria.

Zhu He H Yang Chao C Li Qiang Q Ren Yang Y Neuefeind Joerg C JC Gu Lin L Liu Huibiao H Fan Longlong L Chen Jun J Deng Jinxia J Wang Na N Hong Jiawang J Xing Xianran X

Nature communications 20181129 1

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 (P4<sub>2</sub>/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 d ...[more]

PMID: 30498209

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