Modification of ferroelectric and resistive properties of (Bi0.5Na0.5)(Nb0.5Fe0.5)O3 -PVDF composite

Pure (Bi0.5Na0.5)(Fe0.5Nb0.5)O-3 [BNFN] ceramic was synthesized via a solid-state reaction route. PVDF and BNFN reinforced PVDF composite were prepared through a solution casting technique. The structure and surface morphology of the samples were studied using X-ray diffraction and scanning electron microscope respectively. Dielectric and impedance measurements were carried out in a frequency range of 1 kHz-1 MHz at different temperatures (25-130 degrees C). On addition of BNFN ceramic, a substantial increase in dielectric constant of the PVDF matrix was observed. The temperature has little effect on the dielectric constant of the composite in the said temperature range but its dielectric loss increases rapidly with rise in temperature. At room temperature the composite sample has dielectric constant of 161.7 and loss of 0.09. The composite exhibited a saturated ferroelectric hysteresis loop with remnant polarization value of 1.5 mu C/cm(2). The electric response was investigated by impedance spectroscopy technique in terms of equivalent electric circuit. The ac conductivity as a function of frequency obeys Jonscher's power law except a small deviation in the low-frequency region. The composite showed improved conductivity.