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We study straight-crested waves and vibration modes with spatial variations along the x3 direction only in an AT-cut quartz plate resonator. The equations of anisotropic elasticity are used. Dispersion relations for face-shear and thickness-twist waves in unbounded plates are plotted. Frequency spectra are obtained for face-shear and thickness-twist vibrations of finite plates in which these modes are coupled by boundary conditions. Most importantly, our analysis produces the frequency spectra for overtone modes which do not seem to have been obtained before for x3-dependent modes. Numerical results for third- and fifth-overtone AT-cut quartz resonators are presented, showing that higher-order overtone modes are associated with more mode couplings. [ABSTRACT FROM AUTHOR]

We study the propagation of thickness-twist and face-shear waves in piezoelectric plates of monoclinic crystals, which include rotated Y-cut quartz and langasite as special cases. The equations of linear piezoelectricity are used. Exact solutions are obtained for both fully-electroded and unelectroded plates. Dispersion relations are plotted for both AT-cut quartz and Y-cut langasite plates. The difference in frequencies between the exact piezoelectric solutions obtained in the present paper and the approximate elastic solutions in the literature is found to be of the order of 1%, which is significant in acoustic wave resonator and sensor applications. [ABSTRACT FROM PUBLISHER]

Typical perovskite oxides SrTiO3 (STO) and PbZr0.52Ti0.48O3 (PZT) were fabricated on GaN semiconductor substrates by pulsed laser deposition. STO and PZT films were deposited on bare GaN, TiO2, and MgO-buffered GaN. The effects of TiO2 and MgO buffer-layers on the orientations and electric properties of the perovskite films were systematically studied. The crystalline properties were in situ monitored by reflective high energy electron diffraction and ex situ characterized by X-ray diffraction. It was found that the epitaxial temperature of STO and PZT was reduced by inserting a buffer layer. (111)-oriented films were obtained on bare and TiO2-buffered GaN. However, the orientations of the perovskite films were changed to be (110) when deposited on MgO buffer layer. Furthermore, PZT films deposited on MgO- and TiO2-buffered GaN show better electric performance compared with these films directly deposited on GaN. These results show that perovskite oxide could be epitaxially grown on GaN semiconductor substrates by inserting a proper buffer layer. [ABSTRACT FROM PUBLISHER]