Ferroelectric properties and ac conductivity studies of yttrium modified Pb(Fe0.5Nb0.5)O3 ceramics

Using a high-temperature standard solid-state reaction (i.e., mixed oxide) method several yttrium modified ferroelectric ceramics of type Pb1−xYx(Fe0.5Nb0.5)1−x/4O3 (PYFN)with different concentration (x = 0.00, 0.02, 0.04, 0.06, 0.08) were prepared. Preliminary X-ray structural analysis reveals that all the samples were crystallized in monoclinic crystal system. The crystal structure is almost invariant with small Y-concentration. Microstructure of the samples exhibits grain growth on increasing Y content. Curie temperature of Y-substituted samples decreases slightly as compared to that of PFN (Pb(Fe1/2Nb1/2)O3). However, Y substitution results in a notable enlargement of 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 x = 0.00 (4.6 μC/cm2). A phenomenological model (i.e., ferroelectric capacitor model) used to simulate hysteresis loops was found to be suitable to explain experimental results. Jonscher's single power law (σac(ω) = σ(0) + Aωn) was well fitted to the frequency dependence of conductivity for all the samples.

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