Ultrasonic Measurements on Rochelle Salt Crystals

Abstract

A pulse technique at 10 Mc/sec. has been used to study the anomalous elastic properties of rochelle salt single crystals at temperature around the upper Curie temperature. The temperature dependence of foiled crystal constant $S_{44}^{}{}_{}{}^{E}$ and of the attenuation of waves which contain a component of shear strain in the $X$ crystallographic plane is reported. The attenuation measurements are formulated in terms of the interaction theory.The dependence of the velocity in 45\ifmmode^\circ\else\textdegree\fi{} $X$ cut crystals of rochelle salt on a d.c. field in the $X$ crystal-lographic direction shows a marked unipolarity. This change in velocity which is caused by the bias field arises from the two following sources: one is the usual saturation on effect which produces a change in velocity that is independent of the polarity; the other is the morphic effect which results from the induced monoclinic constants, and which produces a velocity change, the sign of which is dependent on the polarity.