Anisotropic Ultrasound Propagation in a Smectic-ALiquid Crystal

Abstract
An anisotropic ultrasonic velocity in smectic-A diethyl 4,4′-azoxydibenzoate was measured at 2, 5, 12, and 20 MHz. The material was aligned by slowly cooling through the phase transition point in a magnetic field of 12.4 kOe. An accuracy of ±0.08% in the relative velocity was provided by the phase-matching technique, and three elastic constants were calculated.