Effect of co-substitutions (Ca-Mn) on structural, electrical and magnetic characteristics of bismuth ferrite

摘要

The polycrystalline samples of (Bi1-xCax)(Fe1-xMnx)O-3 with x=0, 0.05, 0.10, and 0.15 mol fraction were prepared by synthesizing through initial mixing of precursors by high-energy ball milling, and subsequent thermal treatment of the milled powders. Study of basic crystal parameters using x-ray diffraction technique of the calcined samples suggests that all the materials are crystallized in the distorted-perovskite (rhombohedral) structure which was supplemented and supported by their FTIR studies. The dielectric properties of the materials were investigated as a function of temperature and frequency and the temperature dependent dielectric constant and loss tangent of the modified system vary with substitution concentration (x) and frequency. Detailed studies of impedance exhibit that the electrical properties of the prepared systems are strongly dependent on temperature and frequency; and thus show a good correlation with their microstructures (i.e. bulk, grain boundary, etc.). Further, it is interesting, to see the contributions of bulk, grain boundary and electrode in the impedance plots. The decrease in value of bulk resistance on increasing temperature suggests the existence of negative temperature co-efficient of resistance (NTCR) behavior in the materials. Room temperature M-H hysteresis measurements reveal that magnetization increases due to the structural distortion, and partial destruction of spin cycloid is caused by co-doping in BiFeO3 ceramics. Unlike magnetic response, the ferroelectric properties of the samples were found be enhanced on increasing mole fraction of x in BiFeO3. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.