Ferroelectric phase transition in RbH₂PO₄ has been investigated using propagation of longitudinal acoustic waves along the polar axis near the transition temperature. The velocity of this mode is continuous across the transition temperature. Velocity data in the ferroelectric phase are analyzed in terms of coupled soft modeacoustic mode model of Pytte to obtain the temperature dependence of the soft mode frequency. The attenuation data in the ferroelectric phase show power law dependence. It follows scaling behaviour of the type predicted by Kawasaki from the mode-mode coupling theory and the dynamical scaling.

Two aspects of ultrasonic attenuation in superconductors are examined: (i) electron drag on dislocations and (ii) anomalous results in energy gap measurements. None of these features is physically understandable at present.

We report here the results of our heat capacityC_p measurements on a monophasic material HoBa₂Cu₃O_7−y. ΔC_p/T_c, the jump inC_p at the superconducting transition temperature (=91 K) of the material is measured to be 31 mJ/mol-K².