This paper is concerned with the electromechanical coupling factors for bulk waves in KNbO/sub 3/ crystal. The dependence of coupling factors on the orientation of vibrators for various types of vibration modes has been calculated. As a result, it has been found that most of these coupling factors are very large at certain orientations of vibrators. Especially, the maximum coupling factor of the thickness-extensional mode excited with a perpendicular field, k/sub t/, is as high as 69% for the rotated X-cut by an angle 49.5/spl deg/ about the Y-axis; that of the thickness-shear mode, k/sub s/, is 88% for the X-cut. To the best of our knowledge, these coupling factors are the highest among those of known piezoelectrics. It has also been found that the coupling factor of the width-extensional mode of a thin finite-width plate with electrodes on its edges, k/sub ww/', is 82% for the rotated Z-cut by an angle 43.5/spl deg/ about the Y-axis. This vibrator would be promising as elements of phased array ultrasonic probes.
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机译：本文涉及KNbO / sub 3 /晶体中体波的机电耦合因子。对于各种类型的振动模式，已经计算出耦合因素对振动器定向的依赖性。结果，已经发现，在振动器的某些方向上，大多数这些耦合因子非常大。尤其是，对于绕Y轴旋转4角度/ spl度/的X形切割，在垂直场激励下的厚度-延伸模的最大耦合系数k / sub t /高达69％。对于X切，厚度剪切模式的k / sub s /为88％。据我们所知，这些耦合因子在已知压电器件中是最高的。还发现，对于旋转Z形切割角度为43.5 / spl的有限宽度薄板，其边缘在其电极上，其宽度-延伸模式的耦合因子k / sub ww /'为82％ deg /绕Y轴。这种振动器有望作为相控阵超声探头的元件。
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