硅酸盐四面体链扭曲驱动的铁电性
Ferroelectricity Driven by Twisting of Silicate Tetrahedral Chains
摘要：
常规的钙钛矿型铁电体基于氧的八面体单元，并且通常包含有毒的Pb以实现稳健的铁电性。在这里，我们报告的铁电性的硅酸盐基化合物，Bi 2SiO 5（BSO），诱导相应的硅酸盐四面体链的结构不稳定性。低能声子模在~ 673 K时凝聚，引起适当的铁电相变。在BSO单晶中观察到极化开关，矫顽场为30 kV/cm，沿垂直于解理面的方向的自发极化为0.3 microC/cm 2。通过第一性原理计算估计面内偏振为23微C/cm 2。本研究结果为基于SiO 4四面体单元的铁电材料的设计提供了新的指导，SiO 4四面体单元广泛存在于天然矿物中。
英文摘要：
Conventional perovskite-type ferroelectrics are based on octahedral units of oxygen, and often comprise toxic Pb to achieve robust ferroelectricity. Here, we report the ferroelectricity in a silicate-based compound, Bi2SiO5 (BSO), induced by a structural instability of the corresponding silicate tetrahedral chains. A low-energy phonon mode condenses at ~ 673 K to induce the proper ferroelectric phase transition. Polarization switching was observed in a BSO single crystal with a coercive field of 30 kV/cm and a spontaneous polarization of 0.3 microC/cm2 along a direction normal to the cleavage plane. The in-plane polarization was estimated by first principles calculations to be 23 microC/cm2. The present findings provide a new guideline for designing ferroelectric materials based on SiO4 tetrahedral units, which is ubiquitously found in natural minerals.
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