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A new three-phase PZT/C/PVC composite comprising PZT (50vol%), nanocrystalline PVC (50 vol%) and a small volume fraction f of carbon black (C) was prepared by the hot-pressing technique. The dielectric property of the composite as a function of the frequency and the dielectric and piezoelectric properties as a function of the volume fraction f of C were studied. The measured dielectric property demonstrates that a percolation transition occurs in the three-phase composites as in normal two-phase metal-insulator continuum media. The dielectric constant varies slightly with f at f<0.1 and increases rapidly when f is close to the percolation threshold at 1 kHz. The optimum properties were obtained for f=0.5 before the percolation threshold in the PZT/C/PVC (50/f/(50-f)vol%) composite with its d_ 33 (20 pC/N) being 50% higher than that of the PZT/PVC (50/50vol%), and its g_ 33 (47.23×10 -3 Vm/N) and K_p (0.25) much higher than the earlier reported values. XRD patterns and P-E hysteresis loops were used to interpret the experimental results.
A new three-phase PZT / C / PVC composite comprising PZT (50 vol%), nanocrystalline PVC (50 vol%) and a small volume fraction f of carbon black (C) was prepared by the hot-pressing technique. The dielectric property of the composite as a function of the frequency and the dielectric and piezoelectric properties as a function of the volume fraction f of C were studied. The measured dielectric property demonstrates that a percolation transition occurs in the three-phase composites as in normal two-phase metal The insulator constant varies slightly with f at f <0.1 and increases rapidly when f is close to the percolation threshold at 1 kHz. The optimum properties were obtained for f = 0.5 before the percolation threshold in the PZT / C / PVC (50 / f / (50-f) vol%) composite with its d_33 (20 pC / N) being 50% higher than that of the PZT / PVC 10 -3 Vm / N) and K_p (0.25) much higher than the earlier reported values. XRD patterns and PE hysteresi s loops were used to interpret the experimental results.