An exact approach is used to investigate Love waves in functionally graded piezoelectric material (FGPM) layer bonded to a semi-infinite homogeneous solid. The piezoelectric material is polarized in z-axis direction and the material properties change gradually with the thickness of the layer. We here assume that all material properties of the piezoelectric layer have the same exponential function distribution along the x-axis direction. The analytical solutions of dispersion relations are obtained for electrically open or short circuit conditions. The effects of the gradient variation of material constants on the phase velocity, the group velocity, and the coupled electromechanical factor are discussed in detail. The displacement, electric potential, and stress distributions along thickness of the graded layer are calculated and plotted. Numerical examples indicate that appropriate gradient distributing of the material properties make Love waves to propagate along the surface of the piezoelectric layer, or a bigger electromechanical coupling factor can be obtained, which is in favor of acquiring a better performance in surface acoustic wave (SAW) devices.
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http://dx.doi.org/10.1016/j.ultras.2006.09.004 | DOI Listing |
Chemistry
January 2025
Lund University: Lunds Universitet, Centre for Analysis and Synthesis and NanoLund, 22362, Lund, SWEDEN.
Lead-based piezoceramics are the dominant materials used in electronic devices, despite the known toxicity of lead. Developing safer piezoelectric materials has inspired the pursuit of lead-free piezoceramics, however some challenges remain in accessing these materials reproducibly. Here we demonstrate a simple and robust method for synthesis of the lead-free piezoceramic material, potassium sodium niobate (KxNa1-xNbO3, KNN) via an aqueous route.
View Article and Find Full Text PDFNat Commun
January 2025
LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore.
Lattice strain plays a vital role in tailoring the optoelectronic performance of colloidal nanocrystals (NCs) with exotic geometries. Although optical identifications of lattice strain in irregular-shaped NCs or hetero-structured NCs have been well documented, less is known about optical signatures of the sparsely distributed lattice mismatch in chemically-doped NCs. Here, we show that coherent acoustic phonons (CAPs) following bandgap optical excitations in Cu-doped CdSe colloidal quantum wells (CQWs) offer a unique platform for indirectly measuring the dopant-induced lattice strain.
View Article and Find Full Text PDFNat Nanotechnol
January 2025
Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, China.
Skyrmions can form regular arrangements, so-called skyrmion crystals (SkXs). A mode with multiple wavevectors q then describes the arrangement. While magnetic SkXs, which can emerge in the presence of Dzyaloshinskii-Moriya interaction, are well established, polar skyrmion lattices are still elusive.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Physics Department, Materials Genome Institute, State Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of High Temperature Superconductors, International Centre for Quantum and Molecular Structures, Shanghai University, Shanghai, 200444, China.
Correction for ' study of temperature-dependent piezoelectric and electronic properties of thermally stable GaPO' by Xiaoqing Yang , , 2024, , 21530-21537, https://doi.org/10.1039/D4CP02270J.
View Article and Find Full Text PDFNat Commun
January 2025
State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle, College of Mechanical and Vehicle Engineering, Hunan University, Changsha, China.
Electrostriction is an important electro-mechanical property in poly (vinylidene fluoride) (PVDF) films, which describes the proportional relation between the electro-stimulated deformation and the square of the electric field. Generally, traditional methods to improve the electrostriction of PVDF either sacrifice other crystalline-related key properties or only influence minimal regions around the surface. Here, we design a unique electret structure to fully exploit the benefits of internal crystal in PVDF films.
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