Influence of divalent Ni and trivalent Cr ions on the properties of ytterbium modified bismuth ferrite

• Synthesis by sol-gel method.
• Decrease in band gap is observed with Ni and Cr co-doping.
• Conduction mechanism is found to be different in Ni and Cr co-doped samples.
• Maximum polarization follows a similar trend as leakage current density.

Different concentrations of Ni2+ and Cr3+ ions are individually doped in the Fe site of Bi0.95Yb0.05FeO3 and its effect on structural, band gap, magnetic and electrical properties of bismuth ferrite is analyzed. Samples are synthesized using citrate based sol-gel method. XRD pattern of all the samples confirmed the formation of BFO with rhombohedral crystal structure. Reflectance spectra of the samples show band corresponding to charge transfer and d-d transitions in Fe. The direct band gap of the samples is calculated using Kulbeka-Munk theory. When compared to Yb modified BiFeO3, an enhancement of magnetization is observed in the Ni co-doped samples and variation with increase in Cr concentration is seen. All the Ni co-doped samples display high leakage behavior, whereas 1, 3 Cr co-doped samples show low leakage and an increase is observed for 5% Cr concentration. The conduction mechanism responsible for the leakage behavior in the Ni co-doped and Cr co-doped samples is found to be different. Ferroelectric measurements show ferroelectric behavior in all the samples. In Ni co-doped samples, the conducting nature has an influence on observed ferroelectric behavior.

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