Silicone Rubber Composites of Differently Fired Cadmium Oxide and Their Positron Lifetime Study

Abstract

Cadmium oxide (CdO) exhibit altered properties with altered Cd: O composition after heat treatment at different temperatures. This has been probed experimentally by various techniques. High electrical conductivity (low resistivity of ~2m Ωcm) after 800 °C firing has inspired novel applications, in many of which the brittleness of the fired ceramic become a bottleneck. Here, flexible composites of these fired cadmium oxides have been formed with a silicone rubber binder and tested with respect to properties like carrier concentration and fractional free volume by positron lifetime spectroscopy. Fractional free volume, V f , 15.32% in the pure silicone rubber, reduces to 9.40% for the composite with 59.13 wt% of 800 °C fired cadmium oxide. Bulk lifetime τ B for positrons in a sample is shorter for higher number density of electrons in the bulk. It reduces from 203.78ps for pure silicone rubber, to 174.01ps for the same composite.