Structural, ferroelectric and impedance spectroscopy properties of Y3+ modified Pb(Fe0.5Nb0.5)O3 ceramics

Some ceramic samples of Pb1−xYx(Fe0.5Nb0.5)1−x/4O3 (PYFN) (0.00≤x≤0.08) were synthesized by a mixed oxide route. X-ray diffraction patterns of all the above samples confirm the formation of single phase material crystallizing in monoclinic structure. Dielectric properties (εr and tan δ) were analyzed in a wide temperature (30-350 °C) and frequency range (100 Hz-1 MHz). Ferroelectric properties of these compounds were confirmed from polarization (P-E hysteresis loop) measurements at room temperature. All the room temperature hysteresis loops of PYFN ceramics were well simulated using the ferroelectric capacitor model. Yttrium substitution resulted in notable enlargement of room temperature remnant polarization (2Pr). The 2Pr of PYFN (x=0.02) reaches to a large value (23 μC/cm2), which is nearly 5 times greater than that of PFN ceramic (4.6 μC/cm2). All the compounds exhibits negative temperature coefficient of resistivity (NTCR) type behavior as that of semiconductors. Dc conductivity (estimated via bulk resistivity) variation with temperature of all the samples follows Arrhenius type of electrical conductivity.