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Increasing demand of multifunctional devices has attracted researchers and scientists toward materials having magnetoelectric coupling as they can provide an extra degree of freedom to device fabrication. In this regard, composites of antiferromagnetic perovskites and ferromagnetic spinels comprise a prospective recipe. Here, we report (1-x)BiFe 0.9 Mn 0.1 O 3 -xNiFe 2 O 4 (x = 0.00, 0.10, 0.20, 0.30, 0.40, and 0.50) nanocomposites prepared by a two-step route. Analysis of the data obtained from diffractometer confirmed the corresponding crystalline phases of Mn-doped BiFeO 3 and NiFe 2 O 4. Formation of nanoparticles was confirmed by field emission scanning electron microscope. Presence of stoichiometric amounts of all elements in composites was confirmed by energy dispersive X-ray spectroscopy. To understand the dielectric relaxation phenomenon, we examined dielectric spectra in a wide frequency range, something that helped us probe the nature of charge transition inside the samples. Increasing NiFe 2 O 4 contents in composites improved the ferroelectric and magnetic response of the material with noticeable magneto-electric coupling, showing the potential of these composites for multifunctional device fabrication. [ABSTRACT FROM AUTHOR]

Abstract An extensive study of oscillatory response of structural and magnetic behavior of phase pure bismuth iron oxide (BiFeO 3) thin films is reported in the present study. Sol-gel method is used to synthesize BiFeO 3 sols at room temperature. Molarity, being an important parameter in chemical synthesis, is varied (0.25 M, 0.3 M, 0.35 M, 0.4 M, 0.45 M, 0.5 M, 0.55 M and 0.6 M) and the effect is investigated in detail. Spin coated thin films are structurally studied by X-ray diffraction (XRD) method. Films prepared using 0.35 M and 0.5 M sols confirm the formation of pure hexagonal phase of perovskite structure with R3c (161) space group. Strengthening of BiFeO 3 phase is observed after magnetic field annealing (MFA) of samples at 300 °C for 2 hours. Mixed bismuth iron oxide phases (i.e. bismuth rich or deficient) are observed in thin films prepared using rest of the sols. Preferred orientation oscillates between (122) and (315) as a function of the appearance of pure and mixed BiFeO 3 phases, respectively. Refined XRD parameters show -ive tilt in bond angle (i.e. ~ -7.148°) in the films with mixed bismuth iron oxide phases. Whereas, +ive tilt (i.e. 2.55° and 4.49°) in bond angles are responsible for the appearance of phase pure bismuth iron oxide phase at 0.35 M and 0.5 M sol concentration. Room temperature ferromagnetic behavior with high value of saturation magnetization is observed for films prepared using 0.35 M (109 emu/cm3) and 0.5 M (135 emu/cm3) sols. Law of approach to saturation magnetization is used to calculate magneto crystalline anisotropy. Graphical abstract fx1 Highlights • Bismuth iron oxide films were prepared using sol-gel and spin coating method. • Molarity of sols was varied in the range of 0.25–0.6 M. • Aqueous media was used for the preparation of BiFeO 3 sols with 1:1 of HCl and ethylene glycol. • Phase pure BFO was observed at 0.35 and 0.5 M sol concentration. • Preferred orientation, crystallite size and dislocation density exhibited oscillatory behaviour. • 3D diamond structures showed -ive tilt in bond angle for mixed phases and +ive tilt for phase pure bismuth iron oxide. • Higher values of saturation magnetization were observed at 0.35 and 0.5 M sol concentrations. • Change in easy axis of magnetization from ⟘ to // along with low anisotropy constant were observed at room temperature for 0.35 and 0.5 M. [ABSTRACT FROM AUTHOR]