The absolute thermopower of single phase YBa₂Cu₃O₇ and Y_0.8Er_0.2Ba₂Cu₃O₇ has been measured in the range 250 K to the superconducting transition temperature. It is found that these compounds show a large enhancement of thermopower in the range 150 K down toT_c. This enhancement shows a steep exponential drop as the temperature increases from the transition temperature. The temperature variation of the enhancement is too steep to be accounted for by electron-phonon or electron-local structural excitation mechanisms.

Electrical resistivity measurements under pressure and lattice parameter study on SmSe_1−xAs_x are reported here. The estimate d lattice parameter and valence is calculated for the same and they are found to be in good agreement with the experimental data. The electrical conductivity increases with the increase of As concentration.

Results are presented on the measurements of unit cell parameter and electrical resistivity under pressure on SmSe_1−xAs_x forx=0.1, 0.2, 0.3 and 0.4. The electrical resistivity values are found to be decreasing with increase of pressure and also with increase of arsenic concentration. The semiconductor to metallic transition is induced by chemical alloying of SmSe with SmAs similar to that observed under pressure. The electrical resistivity values are also calculated which are in good agreement with the experimental values. In this calculation, the carrier mobility is of negative sign and so the sample SmSe_1−xAs_x is found to ben-type semiconductor.