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Fityk peak fitting video7/5/2023 Polycrystalline NdFeO 3 has been prepared by adopting non-conventional methods, for instance sol–gel citrate method, 18,19 hydrothermal route, 20 auto combustion technique, 21 molecular precursor method, 22 and vertical floating zone method. 17 Hence, formation of such a metastable compound is feasible if a well-controlled synthesis method is adopted. The tolerance factor (t = 0.9) for NdFeO 3 is found to lie between these limited values. The stable perovskite structure has a limited value between 0.8 and 1. The ideal perovskite structure has t = 1. This ratio describes the degree of distortion in the compound. Where R A and R B are the ionic radii of the A site and B site cations, respectively, and R O is the ionic radius of oxygen. The long range antiferromagnetic ordering due to the Fe-O-Fe super exchange interaction and the unusual ferroelectricity, both occurring at the room temperature, fulfill the need for potential applications in sensing, actuation, memory, etc., by allowing an additional degree of freedom in device design. 13–15 This distortion along with the canted antiferromagnetic (AFM) G-type magnetic structure at room temperature 16 induces spontaneous reversible electrical polarization with strong coupling between magnetic and electrical order parameters, thus making it a novel multiferroic material. Due to the distortion, corner shared FeO 6 octahedra in the unit cell are tilted and the angle of tilting changes with temperature. This distortion increases when Nd is replaced with other rare earth elements having higher atomic number. The distortion occurs due to the presence of rare earth (RE) element Nd. 9–12 NdFeO 3 orthoferrite adopts distorted orthorhombic perovskite structure with Pbnm space group. Most appealing is the spin reorientation transition of the ordered Fe 3+ magnetic moments in which the direction of the magnetization of Fe 3+ ions changes from the easy axis to the other crystal axis. 8,9 As a result, each interaction dominates the other at some particular temperature. These interactions are greatly influenced by the temperature because structural parameters such as bond angles and bond distances between the magnetic ions are temperature dependent. The competition of Fe-O-Fe, R-O-Fe, and R-O-R interactions leads to surprising magnetic phenomena. 7 Rare-earth orthoferrite invoked attention mainly due to its interesting magnetic properties which arise from the super exchange interactions between two different types of magnetic sub lattices: Fe 3+ and R 3+. Among many, rare-earth orthoferrite having perovskite structure is promisingly suitable for a wide variety of applications with the photo catalytic property it helps in solving environmental and energy crisis, 1–3 and with the peculiar magneto-optical properties it finds application in many optical devices, such as optical isolator, switch, memory, and sensor, 4–6 and is used as cathodes in solid oxide fuel cells. Multi-functional orthoferrite materials with their strong correlation between structural, magnetic, electrical, and optical properties meet the desperate urge for miniaturized and integrated devices. Magnetic field has influence on the dielectric constant as evident from the impedance spectroscopy, indicating the strong coupling between ferroelectric and the magnetic structure of NdFeO 3. The lossy natured ferroelectric loop having a maximum polarization of 0.23 μC/cm 2 at room temperature is found to be driven by the non-collinear magnetic structure with reverse Dzyaloshinskii–Moriya effect. The direct band gap is estimated to be 2.39 eV from the diffuse reflectance spectrum. Absorption bands in the visible ambit, apparent from the UV-Vis diffuse reflectance studies, is found due to the crystal ligand field of octahedral oxygen environment of Fe 3+ ions. Magnetization measurement illustrates antiferromagnetic behaviour with a weak ferromagnetic component caused by the canted nature of the Fe 3+ spins at room temperature. Rietveld refinement of the room temperature X-ray diffraction pattern shows that the Fe-O-Fe bond angle significantly favors the super exchange interaction, which is predominantly antiferromagnetic in nature. It is established that structural arrangement of NdFeO 3 regulates the multifunctional feature of the material. Phase pure NdFeO 3 has been achieved using high energy ball milling of oxide precursors with subsequent sintering.
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