A new technique to assess electrical behaviour by microwave measurements, application to Perovskites RNiO(3) (R=Nd, Sm)

An original technique to measure conductivity and Hall effect on powdered samples at microwave frequency is presented. A microwave electric field (E) over right arrow and a perpendicular magnetic field (B) over right arrow induce an effect on the motion of electric charges and a component of the movement appears along the direction (E) over right arrow A (B) over right arrow. This motion generates, in a cavity, a new mode of oscillation. The analysis of the signal allows the study of the charge carriers, especially the sign and the parameters tau/m and n. This new method has been used to measure the conductivity behaviour of perovskites Sm1-xNdxNiO3. It proved possible to detect the metal-insulator transition at room temperature, as well as the nature of charge carriers. (C) 1997 Elsevier Science Ltd.