Piezoelectric and Dielectric Characteristics of Single-Crystal Barium Titanate Plates

T h e physical properties of B a T i 0 3 have been investigated extensively in the last few years, and the ferroelectric characteristics of single crystals have found several applications in electrical circuit devices. On the other hand, applications of the piezoelectric characteristics of BaTiOs have largely been limited to its ceramic form. T h e experiments reported in this paper were initially undertaken to investigate the possible usefulness of the piezoelectric characteristics of BaTiO : i single crystals in practical devices. In the work reported in this paper, dielectric and piezoelectric characteristics of BaTiOa in single crystals were investigated by means of two types of electrical measurements. A crystal plate with electrodes is essentially a two-terminal circuit element. T h e admittance of crystals as passive elements has been measured as a function of average remanent 719 720 THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1 9 5 8 polarization above, below and in the vicinity of the fundamental resonant frequency in the thickness-extensional mode. When such a crystal is excited by ultrasonic radiation it becomes a voltage source. T h e o u t p u t voltage of an ultrasonically excited crystal has been observed as a function of average remanent polarization when the ultrasonic excitation was at frequencies in the vicinity of the f u n d a m e n t a l resonant frequency in the thickness-extensional mode. Certain features of the piezoelectric behavior of B a T i 0 3 single crystals have been measured before by Bond, Mason and McSkimin; 1 by Caspari and Merz; 2 by Drougard and Young 3 and by Iluibregtse, Drougard and Young.