Nowadays, orthotropic piezomaterials have enormous potential in producing electronic devices owing to their inherent merits, e.g., intrinsically robust piezoelectricity. Nevertheless, the previous theoretical studies merely report surface effects on the physical properties of SH waves in a layered transversely isotropic piezoelectric structure. Filling such a blank is a special necessity for optimizing Surface Acoustic Wave (SAW) sensors. Thus, the present paper aims to determine how surface effects and interfacial imperfection affect the attributes of SH waves in a layered orthotropic piezoelectric semi-space by means of surface piezoelectricity theory and a linear spring model. The structure mainly consists of the piezoelectric film's bottom and top surface layers and the imperfect bonding between the piezoelectric film and elastic half-space. To explicitly figure out surface and imperfect interface effects on the mechanical behavior of SH waves in a layered piezoelectric half-space, we extensively derive the phase velocity equations of SH waves in an orthotropic piezoelectric plate and an orthotropic piezoelectric half-space. Then, a comparison study among SH waves in a layered piezoelectric semi-space, a piezoelectric plate, and a piezoelectric half-space is conducted. As a result, it is revealed that the attributes of SH waves dramatically vary as the piezoelectric films’ thickness changes from microscale to nanoscale. In addition, phase velocity increases or decreases with an increasing surface elastic constant or surface density due to the enhancement of stiffness or density of the whole structure. When the ratio of piezoelectric film thickness to wavelength is small, imperfect parameters substantially reduce the phase velocity owing to a decreasing interface elastic stiffness. The comparison study shows that the imperfect parameter does not influence the waves’ velocity, while the ratio of film thickness to wavelength is relatively considerable. Anisotropic piezoelectric constant essentially weakens surface effects on the waves’ velocity. Intriguingly, a linear function is acquired and is used to measure surface density via the slope of the linear function. The summaries supply unique guidelines and instructions to open an avenue for designing and manipulating surface acoustic wave nanosensors in the future.

中文翻译：

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考虑表面效应的正交各向异性压电材料中的 SH 波


如今，正交各向异性压电材料由于其固有的优点，例如固有的鲁棒压电性，在生产电子设备方面具有巨大的潜力。然而，先前的理论研究仅报告了层状横观各向同性压电结构中SH波物理性质的表面效应。填补这样的空白对于优化表面声波（SAW）传感器来说是特别必要的。因此，本文旨在通过表面压电理论和线性弹簧模型确定表面效应和界面缺陷如何影响层状正交各向异性压电半空间中SH波的属性。该结构主要由压电薄膜的底面和顶面层以及压电薄膜与弹性半空间之间的不完美键合组成。为了明确地弄清楚表面和不完美界面对层状压电半空间中SH波机械行为的影响，我们广泛地推导了正交各向异性压电板和正交各向异性压电半空间中SH波的相速度方程。然后，对层状压电半空间、压电板和压电半空间中的SH波进行了比较研究。结果表明，随着压电薄膜厚度从微米级到纳米级的变化，SH波的属性会发生显着变化。此外，由于整个结构的刚度或密度的增强，相速度随着表面弹性常数或表面密度的增加而增加或减少。 当压电薄膜厚度与波长之比小时，由于界面弹性刚度降低，不完美的参数显着降低了相速度。对比研究表明，不完善的参数对波速的影响不大，而膜厚与波长的比值相对较大。各向异性压电常数本质上削弱了表面对波速的影响。有趣的是，获取线性函数并用于通过线性函数的斜率测量表面密度。这些摘要提供了独特的指南和说明，为未来设计和操作表面声波纳米传感器开辟了一条途径。