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标题：Unidirectional thermal expansion in edge-sharing BO₄ tetrahedra contained KZnB₃O₆
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作者：Yanfang Lou ; Dandan Li ; Zhilin Li 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2015
卷号：5
DOI：10.1038/srep10996
出版社：Springer Nature
摘要：Borates are among a class of compounds that exhibit rich structural diversity and find wide applications. The formation of edge-sharing ( es -) BO₄ tetrahedra is extremely unfavored according to Pauling’s third and fourth rules. However, as the first and the only es- borate obtained under ambient pressure, es -KZnB₃O₆ shows an unexpected high thermal stability up to its melting point. The origin of this extraordinary stability is still unclear. Here, we report a novel property in KZnB₃O₆: unidirectional thermal expansion, which plays a role in preserving es- BO₄ from disassociation at elevated temperatures. It is found that this unusual thermal behavior originates from cooperative rotations of rigid groups B₆O₁₂ and Zn₂O₆, driven by anharmonic thermal vibrations of K atoms. Furthermore, a detailed calculation of phonon dispersion in association with this unidirectional expansion predicts the melting initiates with the breakage of the link between BO₃ and es- BO₄. These findings will broaden our knowledge of the relationship between structure and property and may find applications in future.