[6a-A502-1~14] 9.1 Dielectrics, ferroelectrics

▼ [6a-A502-12] Correlation of Surface Damaged Layers and Dielectric, Ferroelectric, and Piezoelectric Properties in Barium Titanate Ceramics

〇(D)Gopal Prasad Khanal¹, Sangwook Kim¹, Ichiro Fujii¹, Shintaro Ueno¹, Chikako Moriyoshi², Yoshihiro Kuroiwa², Satoshi Wada¹ (1.Univ. of Yamanashi, 2.Hiroshima Univ.)

Keywords:Dielectric, Ferroelectric, Piezoelectric Properties

Polishing and cutting are used during ceramics processing, which is believed to induce stress and a surface damaged layer that could deteriorate the electrical properties of ferroelectrics. In this study, a prototypical ferroelectric: barium titanate (BaTiO₃, BT) piezoelectric ceramics were prepared conventionally using hydrothermal nanometer-sized barium titanate powder. Polished and cut BT ceramics were annealed at several conditions for recovery, and the crystal structures and electrical properties were investigated as a function of annealing temperatures. The electrical measurements revealed a reduction in the coercive field, elimination of internal bias and an increase in saturation polarization in the thermally annealed samples. Furthermore, the electromechanical properties measured by resonance method, prior to thermal annealing are d₃₃= 184 pC/N, k₃₃= 0.36, Q_m= 99, while the values after 1200 ^oC-4 h thermal annealing are d₃₃= 287 pC/N, k₃₃= 0.54, Q_m= 184. The mechanism for the electrical properties enhancement after thermal annealing is discussed in terms of in situ crystal structure analysis using synchrotron X-ray diffraction and laboratory Cu Kα X-ray diffraction. This study elucidates the basic and fundamental principle for the properties enhancement of barium titanate ceramics with the recovery of the surface damaged layer by thermal annealing.