Enhanced multiferroic response in new binary solid solution (0.5)Bi0.70A0.30FeO3–(0.5)PbTi0.5Fe0.5O3 (A = Sr, Pb, and Ba) systems

Abstract

Abstract New (0.5)Bi0.70A0.30FeO3–(0.5)PbTi0.5Fe0.5O3 (A = Sr2+, Pb2+, and Ba2+; denoted as A30-Fe50) binary solid solutions with multiferroic properties were synthesized via solid-state method. X-ray diffraction and a subsequent Rietveld analysis of the data for solid solutions confirmed the presence of multiphase (R3c, Pm 3 ¯ m & P4mm) in the binary systems. Deconvoluted Raman spectra helped us to understand the variation of phonon modes. The overlapping and weakening of modes are ascribed to the structural changes/transformation whereas modes’ shifting is attributed to the changes in average atomic mass at A/B-sites. The magnetic properties of the binary systems showed an increase in average magnetization. We found a systematic increase in magnetization of binary systems which correlates well with the size variance (ri; Ba2+ > Pb2+ > Sr2+ > Bi3+) effect introduced in BiFeO3 phase and the highest magnetization was observed for Ba30-Fe50 binary system. Moreover, Pb30-Fe50 and Ba30-Fe50 systems exhibited enhanced magnetization compared to the sum of constituent phases while the Sr30-Fe50 system exhibited the average trend of saturation magnetization. This improvement in magnetic properties of solid solutions can be attributed to the suppression of spin spiral modulated structure as well as possible changes in Fe O local environment which effects the superexchange interaction. Moreover, Pb30-Fe50 binary system exhibited improved dielectric and ferroelectric properties which can be attributed to the existence of lone pair ion Pb which has high polarizability and a higher percentage of tetragonal symmetry in the system. Thus, a significantly high magnetization, high value of dielectric constant, small dielectric loss, and a good ferroelectric response of Pb30-Fe50 system makes it the best among the three studied systems and a promising candidate from an application point of view.