Abstract
In the present paper we report experimental results of the velocity and attenuation of ultrasonic longitudinal waves in TSCC ((CH3NHCH3COOH)3- CaCl2), which is an uniaxial ferroelectric below 127 K with a phase transition of the second order of order-disorder type.1–3 In the paraelectric phase (D2k = mmm) and in the ferroelectric phase (C22k = mm2) TSCC belongs to the orthorhombic system? An anomalous increase of the attenuation in y-direction of sound waves and a step-like behaviour of the sound velocities v 22 and v 11 were observed.