Microstructure Control of Grain-oriented Barium-titanate Ceramics and Their Piezoelectric Properties

摘要

A templated grain growth (TGG) method was used for the preparation of grain-oriented barium-titanate (BaTiO3, BT) ceramics. [110]-oriented BT plate-like template particles were dispersed in a matrix of hydrothermal BT spherical particles of various sizes. The Lotgering method using the X-ray diffraction (XRD) pattern determined the degree of orientation along the [110] direction (F-110). An optimization of the preparation conditions was performed in terms of the template-to-matrix weight ratio (T/M), the Ba/Ti ratio, and the sintering temperature and time in order to achieve a high F-110 along with a small grain size and a high density. A grain size as small as 10 mu m could be reached for Ba/Ti ratios close to the stoichiometric value. Lower values led to an increase in F-110 and in the grain size. A T/M bigger than 80% was necessary for F-110 to be above 80% and for the grain size lower than 40 mu m. The density was almost independent of the T/M and the Ba/Ti ratios. The grain growth was limited by a two-step sintering process. Small grain size, high F-110 and high density are essential if the piezoelectric constant d(33) is to be increased above the values for standard BT ceramics.