共价键
离子键合
纤锌矿晶体结构
铁电性
化学物理
材料科学
对称性破坏
点反射
库仑
凝聚态物理
结晶学
化学
电介质
离子
光电子学
物理
有机化学
量子力学
六方晶系
电子
出处
期刊:Science Advances
[American Association for the Advancement of Science (AAAS)]
日期:2023-01-20
卷期号:9 (3)
标识
DOI:10.1126/sciadv.adf8706
摘要
In the Mooser-Pearson diagram, binary ionic compoundss form into nonpolar symmetrical structures with high coordination numbers, while wurtzite structures should appear in the covalent region. Their tetrahedral bonding configurations break the inversion symmetry, with polarizations almost unswitchable due to the high barriers of abrupt breaking and reformation of covalent bonds. Here, through first-principles calculations, we find some exceptional cases of highly ionic ferroelectric binary salts such as lithium halides, which may form into wurtzite structures with covalent-like sp3 bondings, and the origin of these abnormal formations is clarified. Their high polarizations induced by symmetry breaking are switchable, with much smoother switching pathway refrained from abrupt bond breaking due to the long-range feature of Coulomb interactions. These covalent-like ionic bondings do reduce not only their ferroelectric switching barriers but also the phase transition barriers between polar and nonpolar phases, rendering high performance in applications such as nonvolatile memory and energy storage.
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