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

doi:10.1038/s41467-018-07526-x

Charge transfer drives anomalous phase transition in ceria

Nat Commun. 2018 Nov 29;9(1):5063. doi: 10.1038/s41467-018-07526-x.

Authors

He Zhu^{1

2}, Chao Yang³, Qiang Li^{1

2}, Yang Ren⁴, Joerg C Neuefeind⁵, Lin Gu⁶, Huibiao Liu⁷, Longlong Fan^{1

2}, Jun Chen^{1

2}, Jinxia Deng^{1

2}, Na Wang^{1

2}, Jiawang Hong⁸, Xianran Xing^{9

10}

Affiliations

¹ Beijing Advanced Innovation Center for Materials Genome Engineering, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China.
² State Key Lab for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing, 100083, China.
³ School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China.
⁴ X-Ray Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA.
⁵ Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
⁶ Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Science, Beijing, 100190, China.
⁷ Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
⁸ School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China. hongjw@bit.edu.cn.
⁹ Beijing Advanced Innovation Center for Materials Genome Engineering, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China. xing@ustb.edu.cn.
¹⁰ State Key Lab for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing, 100083, China. xing@ustb.edu.cn.

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.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.