Universal A-Cation Splitting in LiNbO3-Type Structure Driven by Intrapositional Multivalent Coupling

Yifeng Han, Yijie Zeng, Mylène Hendrickx, Joke Hadermann, Peter W. Stephens, Chuanhui Zhu, Christoph P. Grams, Joachim Hemberger, Corey Frank, Shufang Li, Mei Xia Wu, Maria Retuerto, Mark Croft, David Walker, Dao Xin Yao, Martha Greenblatt, Man Rong Li

Research output: Contribution to journalArticlepeer-review

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Abstract

Understanding the electric dipole switching in multiferroic materials requires deep insight of the atomic-scale local structure evolution to reveal the ferroelectric mechanism, which remains unclear and lacks a solid experimental indicator in high-pressure prepared LiNbO3-type polar magnets. Here, we report the discovery of Zn-ion splitting in LiNbO3-type Zn2FeNbO6 established by multiple diffraction techniques. The coexistence of a high-temperature paraelectric-like phase in the polar Zn2FeNbO6 lattice motivated us to revisit other high-pressure prepared LiNbO3-type A2BB′O6 compounds. The A-site atomic splitting (âˆ1.0-1.2 Å between the split-atom pair) in B/B′-mixed Zn2FeTaO6 and O/N-mixed ZnTaO2N is verified by both powder X-ray diffraction structural refinements and high angle annular dark field scanning transmission electron microscopy images, but is absent in single-B-site ZnSnO3. Theoretical calculations are in good agreement with experimental results and suggest that this kind of A-site splitting also exists in the B-site mixed Mn-analogues, Mn2FeMO6 (M = Nb, Ta) and anion-mixed MnTaO2N, where the smaller A-site splitting (âˆ0.2 Å atomic displacement) is attributed to magnetic interactions and bonding between A and B cations. These findings reveal universal A-site splitting in LiNbO3-type structures with mixed multivalent B/B′, or anionic sites, and the splitting-atomic displacement can be strongly suppressed by magnetic interactions and/or hybridization of valence bands between d electrons of the A- A nd B-site cations.

Original languageEnglish (US)
Pages (from-to)7168-7178
Number of pages11
JournalJournal of the American Chemical Society
Volume142
Issue number15
DOIs
StatePublished - Apr 15 2020

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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