Electrical impedance functionality and spin orientation transformation of nanostructured Sr-substituted BaMnO3 hexagonal perovskites

摘要

Eliminating the undesirable pyrochlore phase is quite essential in order to determine the viable dielectric and magnetic characteristics of perovskite-based materials. In this work, we report the synthesis of stoichiometric Sr-substituted barium manganite namely, Ba1-xSrxMnO3 (x = 0.0, 0.2, 0.4, 0.6 and 0.8) to reveal the improved structural, dielectric and magnetic properties with increase in Sr contents. X-ray diffraction and subsequent Rietveld refinement reveals that with successful substitution of Sr at Ba-site, the pyrochlore phase diminishes and pure perovskite phase is achieved. Scanning electron microscopy demonstrates gradually improved grain shapes and uniformity in sizes in the series. Electrical impedance spectroscopy was performed using an impedance analyzer, to obtain frequency response of dielectric constant, giving tenable information about a sustainable change in electrical permittivity due to Sr substitution which could be used for multilayered chip inductors. Dense dielectric materials with low losses are credible for multilayered components which make these oxides more feasible than ferrites to be used as sheets inside the multilayered chip inductors. Contribution of grains and grain boundaries effect on electrical resistivity, losses and quality factors are also distinguished. The coupling between the magnetic and dielectric order is also confirmed through magneto-dielectric measurement. Low temperature magnetic studies reveals the multiferroic characteristic of the material as the ferromagnetic transition temperature of 55 K, found experimentally has never been reported before. (C) 2017 Elsevier B.V. All rights reserved.