Microwave hall mobility studies on polymer-metal oxide nanocomposites

Films of polymer metal oxide composites with poly(methyl methacrylate) and metallic powders (CuO, Ni, and brushed Fe3O4) were prepared with a spin-casting method. Electric transport studies indicated that the compositions surpassed the percolation threshold limit. Alternating current (AC) conductivity studies confirmed a hopping mechanism with power-law behavior in frequency. For the first time, the mobility values of the carriers in these films were measured by the contactless microwave Hall effect technique with a bimodal cavity operating at 14 GHz. In this technique, a circular bimodal cavity is used to measure the change in the transmission coefficient (proportional to the carrier mobility) due to the application of a static magnetic field perpendicular to the microwave electric fields. The mobility measurements indicated a decrease in mobility with increasing quantity of CuO and Ni and showed an increase in the carrier-lattice scattering, whereas the mobility increased with increasing Fe3O4 due to the negative magneto resistance. © 2007 Wiley Periodicals, Inc.