Universal Geometric Frustration in Pyrochlores

Published

July 5, 2018

Author(s)

Benjamin A Trump, Syed M. Koohpayeh, Ken J. T. Livi, JiaJia Wen, Kathyrn Arpino, Quentin M. Ramasse, Rik Brydson, Mikhail Feygenson, H. Takeda, M. Takigawa, K. Kimura, S. Nakatsuji, Collin L. Broholm, T. M. McQueen

Abstract

We report on the structural details of Pr₂Zr₂O₆O', La₂Zr₂O₆O', and Yb₂Ti₂O₆O' in the A₂B₂O₆O' pyrochlore structure. X-ray and neutron powder diffraction indicate these materials are long-range ordered. On the local scale these materials appear to be disordered despite ideal stoichiometry, ideal cation-ordering, no lone pair-effects, and lack of magnetism (in La₂Zr₂O₇); as evidenced by pair-distribution analysis and selected area electron diffraction at room temperature. High-resolution scanning transmission electron microscopy and ⁹¹Zr NQR indicate that this disorder is static and of order 0.1 Å. The magnitude and pattern for displacements is consistent with a β-cristobalite distortion, due to either an electronic (Jahn-Teller) effect or the size mismatch between A and B cations. The evidence for these distortions has significant implications for materials which crystallize in the pyrochlore structure.

Citation

Nature Communications

Volume

9

Issue

1

Pub Type

Journals

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Keywords

Pyrochlore, geometric frustration, spin-liquid behavior, β-cristobalite, pair-distribution function, scanning transmission electron microscopy

Citation

, B. , , S. , T., K. , Wen, J. , Arpino, K. , , Q. , Brydson, R. , Feygenson, M. , Takeda, H. , Takigawa, M. , Kimura, K. , Nakatsuji, S. , , C. and , T. (2018), Universal Geometric Frustration in Pyrochlores, Nature Communications, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=922150 (Accessed April 18, 2024)