| 摘要 |
PURPOSE:To obtain a composite electrostrictive material made of electrostrictive porcelain composition and polymer substance and having high performance and an ultrasonic vibrator and an ultrasonic probe to be controlled at its electroacoustic conversion efficiency according to a bias electric field intensity by holding powder of specific porcelain composition in sheetlike polymer or vertically burying many fine columnar porcelains of the composition in the sheet face of the polymer. CONSTITUTION:The composition of an electrostrictive porcelain for an ultrasonic vibrator is generated by a general formula (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3, where 0.05<=x<=0.12. For example, as the starting material of the composition, lead oxide (PbO), niobium oxide (Nb2O5), magnesium oxide (MgO) and titanium oxide (TiO2) is employed, they are weights in predetermined composition, and wet mixed with acetone in a ball mill. In the composition, the composition in which thickness vibration electromechanical coupling coefficient kt is 0.30 or more in a bias electric field of 400V/mm at a temperature range of 15-40 deg.C and the remainder of the kt becomes less than 0.1 at the time of removal of the bias electric field can be selected. Accordingly, the composition in which electromechanical coupling coefficient equivalent to that of a conventional PZT piezoelectric vibrator can be induced in an ambient temperature available environment is obtained. |
