Tetra-needle zinc oxide/silica composites: High-temperature dielectric properties at X-band

Nano-structural ZnO of unique electrical and optical properties is highly attractive in dielectric and microwave applications, specifically considered as ideal fillers for achieving light-weight composites. In this work, tetra-needle ZnO (T-ZnO) by a direct combustion approach was selected as the filler in silica nanopowders for fabricating T-ZnO/SiO2 composites. Temperature effects on dielectric properties of the composites were investigated in the temperature range of 300-700 degrees C at 8.2-12.4 GHz. The observed imaginary permittivity and loss tangent was found to be temperature dependent, and the mechanism associated with relaxation and electrically conductive loss was discussed. (C) 2012 Elsevier Ltd. All rights reserved.