First-Principles Study of Piezoelectric Properties and Bonding Analysis in (Mg, X, Al)N Solid Solutions (X = Nb, Ti, Zr, Hf)
First-Principles Study of Piezoelectric Properties and Bonding Analysis in (Mg, X, Al)N Solid Solutions (X = Nb, Ti, Zr, Hf)
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DOI：
10.1021/acsomega.9b01912
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发表时间：
2019-09-17
期刊：
影响因子：
4.1
通讯作者：
Akiyama, Morito
中科院分区：
文献类型：
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作者：
Hirata, Kenji;Yamada, Hiroshi;Akiyama, Morito
用第一性原理计算方法研究了在氮化铝（AlN）中共掺杂Mg + X （X = Nb, Ti, Zr, Hf）增强压电性能的机理。理论上，当弹性常数C-33减小，压电应力常数e（33）增大时，可以增大压电常数d（33）。在AlN中加入Mg + X可以提高e（33）的所有分量，包括夹固的e（33）、Born有效电荷（Z(33)）和内部参数的应变灵敏度（du/d epsilon）。Mg + x共掺杂AlN中C-33的减少和du/d epsilon的增加表明发生了弹性软化，这被认为是受纤锌矿结构中原子间键变化的影响。用晶体轨道Hamilton居群对Mg + x共掺杂AlN体系中金属-氮（Me-N）对的成键分析表明，其共价键（Me-N）弱于纯AlN体系。因此，这种较弱的共价键被认为是弹性软化的起源之一。掺sc的AlN具有比纯AlN更高的压电响应。
The enhancement mechanism of piezoelectric properties codoping Mg + X (X = Nb, Ti, Zr, Hf) into aluminum nitride (AlN) was investigated by first-principles calculations. Theoretically, the piezoelectric constant (d(33)) can be increased when the elastic constant (C-33) is decreased and the piezoelectric stress constant (e(33)) is increased. All components of e(33), which consists of the clamped e(33), the Born effective charge (Z(33)), and the strain sensitivity (du/d epsilon) of the internal parameter, were improved by the addition of Mg + X into AlN. The decrease in C-33 and the increase in du/d epsilon that were observed in Mg + Xcodoped AlN indicate the occurrence of elastic softening which was considered to be influenced by changes in the interatomic bond in the wurtzite structure. The bonding analysis of metal-nitrogen (Me-N) pairs in the Mg + X-codoped AlN system which was carried out by crystal orbital Hamilton populations showed that the covalent bonding (Me-N) was weaker than in pure AlN. Therefore, this weaker covalent bond is considered to be one of the origins of the elastic softening. Similar phenomena were also found for Sc-doped AlN which has higher piezoelectric response than that of pure AlN.