抄録
The fundamental vibrations of the short-cylindrical barium titanate vibrators are investigated. Assumptions are: i) The disk polarized in the direction of thickness is isotropic concerning its elastic properties. ii) The electrostrictivities Γ_<11> and Γ_<12> are connected with the relation: Γ_<12>=σΓ_<11> where σ is Poisson's ratio. Under these assumptions, axially symmetric vibrations of free disks are deduced from the general equations of motion. Two cases, which can be well approximated either by a thin disk or a long bar are considered, because of its difficulty in satisfying all boundary conditions. The corresponding curves for the both cases are connected with each other through the point P_0 of (thickness)/(diameter)≌0. 854, where, fortunately, all boundary condition are satisfied. In measuring the electrostrictive constant εΓ_<11>(ε: susceptibility) or electrostrictivity Γ_<11>, it is more convenient to consider the shape factors χ_1 and χ_2 which are determined by vibrational modes and the configuration of electrodes. The factors χ_1 and χ_2 are computed numerically. The characters of electrostrictive vibrators in the first longitudinal mode are elucidated by this research.
