Structural and magnetic quantification of rhombohedral – Orthorhombic phase transition in gadolinium substituted bismuth ferrite

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Room-temperature X-ray diffraction (XRD), and High-resolution transmission microscopy (HR-TEM) were used to investigate the structural properties of multiferroic Bi1-xGdxFeO3 perovskites, (x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30). The system under investigation was synthesized through a citric acid-based auto-combustion technique. XRD analysis revealed that the pure bismuth ferrite and the gadolinium substituted bismuth ferrite up to x = 0.10 samples composed of a polycrystalline rhombohedral structure (space group R3c (161)), the samples with Gd concentration between x = 0.15 and x = 0.25 show coexistence of rhombohedral and orthorhombic phases. At the same time, Bi0.7Gd0.3FeO3 crystallizes in a pure orthorhombic structure (space group Pbnm (62)). The crystallographic parameters and the ratio of the two competed phases were estimated using Rietveld refinement of XRD data. Williamson-Hall model based on the refined XRD data was used to estimate the average crystallite length and the induced lattice strain. Furthermore, TEM and HR-TEM images coincident with the XRD results. Bi1-xGdxFeO3 nanoparticles display coupling interactions between weak ferromagnetism and canted antiferromagnets at room temperature. The magnetic properties were estimated by analyzing the M(H) hysteresis loops collected using a vibrating sample magnetometer (VSM). This study can sustain new strategies for tailoring new smart materials with different fascinating properties.