Structural Dielectric and Impedance Spectroscopy of YBaCuFeO₅

The layered Perovskite compounds play important role in solid state physics due to their intriguing physical properties. We have investigated the structural, complex dielectric and impedance properties of layered perovskite compound YBaCuFeO5(YBCFO). The YBCFO crystallizes in a non-centrosymmetric crystal structure with space group P4mm.The frequency dependent dielectric permittivity (epsilon') shows two relaxation peaks. Both peaks shift towards higher frequency with increasing temperature and follow Arrhenius behaviour with activation energies 0.24 and 0.13 eV respectively. The Nyquist plot resolves the contributionsfrom grain and grain boundaries. The grain boundary contribution dominates at higher temperatures whereas at lower temperature only grain contribution remains. The dielectric measurement combined with Nyquist plots shows that first relaxing peak arises due to grain contribution and hence represents the materials property, whereas the second peaks arises out of grain-boundary contribution.