The lattice dynamics of GaO has been studied on the basis of the three body force shell model, which takes into account the effect of many body interactions in the lattice potential. The dispersion curves obtained by plottingω vsq agree fairly well with the experiments. It is concluded that the value of the molecular electronic polarizability of the solid must be must small than that determined experimentally which suggests that the interaction system in the solid may have a substantial covalent character.

Microwave induced d.c. voltage due to inverse a.c. Josephson effect has been observed across bulk samples of multiphase Y₂BaSrCu₃O₈. Results indicate that weakly coupled superconducting grains probably exist up to 26°C.

Josephson effects have been observed in bulk samples of Y-Ba-Cu-O. The magnitude of the zero-voltage current is found to change systematically with externally applied small magnetic fields of a few mG. It is also found to vary when samples are irradiated with microwaves. These observations suggest the presence of inter-grain Josephson junctions.