Low field ac study of PZT/PVDF nano composites

Composites of nanocrystalline Pb0.96Sr0.04(Zr-0.53,Ti-0.47)O-3 (PZT) and alpha-phase PVDF have been developed using solution casting technique. Characterization of the composites has been done using XRD, FEGSEM, DSC and impedance analysis. XRD and FEGSEM determined the size range of PZT as 22-40 nm. XRD shows the successful incorporation of PZT into PVDF matrix and also confirms that no new phase is developed. DSC of the nanocomposites showed decrease in crystallinity with increasing PZT content. Broadband impedance analysis has been carried out to study the effect of the addition of PZT on the low field ac electrical properties of PVDF. Room temperature dielectric permittivity measurement of the PZT-PVDF composites at 1 kHz determined using impedance analyzer gives values of permittivity 2-4 times higher as compared to neat PVDF. It is found that dielectric permittivity values at the lower frequency edge are affected by space charges while the higher frequencies show the influence of relaxation effects in the materials. It is suggested that PZT/PVDF composites are the preferred materials for high temperature and high frequency applications. However, for low frequency use at higher temperatures, these composites do not offer any specific advantage. At room temperature, the composites are again the better choice in the 1 mHz-1 MHz frequency range.