Effect of Poling Field on Piezoelectric Properties of KNbO3 Crystal Grown by Vertical Bridgman Method

概要

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Single crystals of KNbO3 were grown by the vertical Bridgman method. The crystals were cut into $6\times 3\times 0.5$ mm3 plates, and dielectric constants and resonance characteristics were observed as a function of the electric field strength used in the poling treatment. For the $[001]_{\text{pc}}$-poled crystal, which stands for [001] direction in pseudocubic crystal lattice, the dielectric constant increased once with increasing amount of poling field and then decreased again with higher fields. For $[101]_{\text{pc}}$-poled crystal, both a reduction in dielectric constant and a higher phase angle shift in the resonant region were observed when the electric field exceeded 85 V/mm. The series of observations can be consistently interpreted using the domain structures estimated from the anisotropic dielectric constant. The vibrators having their longitudinal directions along the $a_{\text{pc}}$ and $b_{\text{pc}}$ axes showed quite different piezoelectric responses, revealing that the polarization vector lies only in the $[101]_{\text{pc}}$ and $[\bar{1}01]_{\text{pc}}$ directions.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2004-09-15