Negative-charge-storing mechanism of potassium-ion SiO2-based electrets for vibration-powered generators
Negative-charge-storing mechanism of potassium-ion SiO2-based electrets for vibration-powered generators
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用于振动发电机的钾离子SiO2基驻极体的负电荷存储机制
DOI：
10.1063/5.0029012
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
K. Shiraishi
中科院分区：
文献类型：
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作者：
T. Nakanishi;Takeshi Miyajima;K. Chokawa;M. Araidai;H. Toshiyoshi;T. Sugiyama;G. Hashiguchi;K. Shiraishi
钾离子驻极体是振动式微型机电发电机的关键元件，它可以几乎永久地储存负电荷。然而，这种负电荷的储存机制仍不清楚。利用第一性原理分子动力学计算方法，从理论上研究了含和不含钾原子的非晶态二氧化硅(a-SiO_2)的原子结构和电子结构。我们的计算表明，具有五个Si-O键的五配位Si原子(SiO5结构)是具有钾原子的a-SiO_2的特征局域结构，它变成负电荷，即使在去除钾原子后仍然是如此。这些结果表明，这种SiO5结构是在钾离子驻极体中观察到的强负电荷的物理来源。我们还发现SiO_5结构在1000 cm−_1处有一个拉曼峰。
A potassium-ion electret, which is a key element of vibration-powered microelectromechanical generators, can store negative charge almost permanently. However, the mechanism by which this negative charge is stored is still unclear. We theoretically study the atomic and electronic structures of amorphous silica (a-SiO2) with and without potassium atoms using first-principles molecular-dynamics calculations. Our calculations show that a fivefold-coordinated Si atom with five Si–O bonds (an SiO5 structure) is the characteristic local structure of a-SiO2 with potassium atoms, which becomes negatively charged and remains so even after removal of the potassium atoms. These results indicate that this SiO5 structure is the physical origin of the robust negative charge observed in potassium-ion electrets. We also find that the SiO5 structure has a Raman peak at 1000 cm−1.