Cation disorder in Mg${X}_{2}$O${}_{4}$ ($X$ = Al, Ga, In) spinels from first principles

Cation disorder in Mg $X_{2}$ O $_{4}$ ( $X$ = Al, Ga, In) spinels from first principles

Chao Jiang, Kurt E. Sickafus, Christopher R. Stanek, Sven P. Rudin, and Blas P. Uberuaga

Phys. Rev. B 86, 024203 – Published 23 July 2012

Abstract

We have performed first-principles density functional theory calculations to investigate the possible physical origins of the discrepancies between the existing theoretical and experimental studies on cation distribution in Mg $X_{2}$ O $_{4}$ ( $X$ $=$ Al, Ga, In) spinel oxides. We show that for MgGa $_{2}$ O $_{4}$ and MgIn $_{2}$ O $_{4}$ , it is crucial to consider the effects of lattice vibrations to achieve agreement between theory and experiment. For MgAl $_{2}$ O $_{4}$ , we find that neglecting short-range order effects in thermodynamic modeling can lead to significant underestimation of the degree of inversion. Furthermore, we demonstrate that the common practice of representing disordered structures by randomly exchanging atoms within a small periodic supercell can incur large computational error due to either insufficient statistical sampling or finite supercell size effects.

Received 29 September 2011

DOI:https://doi.org/10.1103/PhysRevB.86.024203

Authors & Affiliations

Chao Jiang^1,*, Kurt E. Sickafus², Christopher R. Stanek³, Sven P. Rudin⁴, and Blas P. Uberuaga^3,*

¹State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, China
²Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
³Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
⁴Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

^*Corresponding authors: chaopsu@gmail.com and blas@lanl.gov

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Vol. 86, Iss. 2 — 1 July 2012

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