Complex permittivity and microwave absorption properties of BaTiO3-polyaniline composite

BaTiO3-polyaniline composites with different mixture ratios, 75/25, 50/50 and 25/75, have been prepared in polyurethane resin, keeping pigment to volume concentration (PVC) constant as similar to 25 in all the samples. For this, BaTiO3 powder by oxide route and polyaniline by chemical oxidation route have been synthesized. The complex permittivity (epsilon'(r) - j epsilon(r)) and reflection loss (dB) of the composites have been measured at different microwave frequencies in X-band (8.2-12.4 GHz) employing vector network analyzer model PNA E8364B and software module 85071. Reflection loss (dB) has been calculated for different thicknesses of the composites using measured values of epsilon(r)' and epsilon(r). It is found that the absorption properties of the composite improve with increasing % of polyaniline. A maximum reflection loss of - 15 dB (97% power absorption) at 10 GHz with a bandwidth of 3 GHz (full frequency width at half of the peak response) has been achieved. Materials can find applications in suppression of electromagnetic interference (EMI), and reduction of radar signature. (c) 2005 Elsevier B.V All rights reserved.