Effect of Poling Field on Piezoelectric Properties of KNbO 3 Crystal Grown by Vertical Bridgman Method

• Published in: Japanese Journal of Applied Physics Vol. 43; no. 9S; p. 6701
• Main Authors: Kudo, Kenichi, Kakiuchi, Kenji, Endo, Naoyuki, Bamba, Noriko, Hoshikawa, Keigo, Fukami, Tatsuo
• Format: Journal Article
• Language: English
• Published: 01-09-2004
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.43.6701

Single crystals of KNbO
3
were grown by the vertical Bridgman method. The crystals were cut into 6×3×0.5 mm
3
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]
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]
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
pc
and
b
pc
axes showed quite different piezoelectric responses, revealing that the polarization vector lies only in the [101]
pc
and [101]
pc
directions.