EFFECT OF COMPOSITIONAL MODIFICATIONS ON DIELECTRIC, FERROELECTRIC AND PYROELECTRIC RESPONSE OF PMN-PT SOLID SOLUTIONS NEAR MPB
Abstract
Morphotropic phase boundary (MPB) compositions of (1-x)PMN-(x)PT system, where x=0.30, 0.32 and 0.34, were prepared in single perovskite phase by the B-site Columbite precursor method. Temperature dependence of dielectric behavior, measured at different frequencies, revealed the transformation of the system from relaxor to normal ferroelectric behavior and decrease in dielectric dispersion near transition temperature (Tc) with the increase in PT content. Appearance of an abnormal hump in the dielectric behavior of PMNT 68/32 composition confirms the MPB nature of the system. Remnant polarization, Pr was found to be ~ 23, 22 and 27 μC/cm2, whereas coercive field, Ec was found to be ~ 3.3, 3.9 and 3.6 kV/cm for PMNT 70/30, 68/32 and 66/34 compositions respectively. Strain versus electric field (S-E) behavior revealed the piezoelectric nature of these compositions with a maximum strain ~ 0.75% at 31 kV/cm applied electric field in PMNT 68/32 composition. Temperature variation of the pyroelectric coefficient, Pi, confirms Tc, as obtained by dielectric measurements.
