Study the influence of Nd and Co/Cr co-substitutions on structural, electrical and magnetic properties of BiFeO3 nanoparticles

Multiferroic BFO nanoparticles of the compositions Bi1−xNdxFeO3 (x=0.05 and 0.1) and Bi0.9Nd0.1Fe0.95TM0.05O3 (Transition Metals, TM=Co and Cr) have been synthesized by low temperature citric acid assisted auto-combustion route. Subsequently, the co-doping effects on structural, dielectric and ferroelectro-magnetic properties of BFO have been investigated. X-ray diffraction analysis hints phase transformation from rhombohedral to orthorhombic for 10% Nd-substituted BFO. TM addition further modifies structure and co-doped samples possess pseudo-cubic symmetry. Magnetic measurement reveals gradual enhancement in weak ferromagnetic nature with increasing doping. A well-developed magnetic hysteresis loop with high magnetization (Mr~0.35 emu/g) and coercive field (Hc~1255 Oe) is observed for Nd-Co co-doped sample, whereas other samples exhibit rarely-observed 'wasp-waisted' type loops. Dielectric behavior is improved significantly on doping. Temperature-dependent dielectric constant presents a broad peak in the vicinity of Neel׳s temperature (TN) for all the samples, signifying strong magnetoelectric coupling. An increment in TN is also observed as a result of Nd-doping and further on adding TM. Leakage current decreases significantly as a result of reduced oxygen vacancies on substitutions. Therefore, co-substitutions of rare-earth and magnetically active transition ions remarkably enrich electric and magnetic characteristics of BFO, and boost multiferroic feasibility.