Analysis of recoverable and energy loss density mediated by Ni/Cr co-doping in BiFeO3

BiFeO₃ is the only multiferroic material in which coexistence of ferroelectricity and anti-ferromagnetism can be seen at room temperature. However, small strength of coupling is a main hurdle for its use in multistate memory devices. The single or co-doping of any other material can improve its multiferroicity. In this regard, we synthesized a series with varying concentration of Ni at the place of Cr in BiFe_0.9Cr_0.1−xNi_xO₃ (x = 0, 0.03, 0.07, 0.1) using sol‒gel auto-combustion route. The rhombohedrally distorted cubic perovskite structure has been observed throughout the series, while the micrographs obtained from scanning electron microscopy exposed that Ni-free composition had diffused grains with no sharp boundaries. Addition of Ni not only reduced the average grain size but also increased the ferroelectric response. Energy density calculations were performed using charge–discharge curves which revealed that increasing Ni/Cr ratio at the Fe site enhanced the energy storage capability. Dielectric study revealed that real part of dielectric constant decreased and concentration-dependent variation remained consistent with morphological change. Impedance spectroscopy exposed that Ni substitution caused an increase in its resistive response, while the relaxation phenomenon and nature of transportation were examined through the shifting of peaks in the complex modulus spectrum.