Electric, magnetic and microstructural features of the La2CoFeO6 lanthanide ferrocobaltite obtained by the modified Pechini route

Abstract

In the search for new materials with applicable magnetic properties in spintronic devices, the aim of this work is to report the synthesis of the lanthanide ferrocobaltite La2CoFeO6 using the modified Pechini route; the experimental study of structural, morphological and magnetic properties, and the analysis of the electronic structure and bands are obtained in the framework of the Density Functional Theory. Rietveld refinement of experimental X-ray diffraction patterns revealed the crystallization of this oxide material in a perovskite-like monoclinic structure, space group [Formula: see text]21/[Formula: see text] (# 14). Scanning electron microscopy and atomic force microscopy images revealed that the surface morphology is essentially polycrystalline, with mean grain sizes between 177 and 188 nm. The dispersive X-ray spectroscopy suggests that the material obtained contains La, Fe, Co and O in the stoichiometric proportions expected by up to 98%. The magnetic susceptibility curves as a function of temperature indicated that the material is ordered ferromagnetically, showing strong irreversibility effects due to the disorder of the Fe and Co cations in the three crystallographic directions of the structure and to the strong distortions in the FeO6 and CoO6 octahedra. Magnetic hysteresis curves confirmed the ferromagnetic character of the material for all temperatures evaluated, up to room temperature. I–V response curves revealed a semiconductor-like behavior with a figure of merit exponent 1.53 of the varistor type. The ferromagnetic semiconductor behavior suggests the potential applicability of the material in spintronic technological devices.

Correlation between the structural phase transition and magnetic properties of sol-gel synthesized nanoparticles

“…Haripriya et al have identified LCFO as a long-range antiferromagnet with a Neel temperature of 270 K, which is observed in the rhombohedral phase [3]. In the recent past, LCFO and doped LCFO have been studied extensively by various researchers for diverse applications [4][5][6][7][8][9][10][11]. It was found that multiple spin states of the transition metal ions in perovskites result in manifestation of multiple magnetic phases in perovskites.…”

“…The crystalline structure of LCFO has been observed in rhombohedral, orthorhombic, monoclinic, or a combination of these phases, as reported by different researchers depending on differences in synthesis routes and experimental parameters [8][9][10]. The crystal symmetry of perovskites is known to have a profound effect on their magnetic properties.…”

“…The crystal symmetry of perovskites is known to have a profound effect on their magnetic properties. For example, Palacio et al inferred that the LCFO prepared by the Pechini method possesses a monoclinic phase, and behaves like a ferromagnetic semiconductor and displays irreversibility temperature, above room temperature [10]. In another study, Wang et al reported the ferromagnetic nature of La 2 Fe 1.20 Co 0.80 O 6 crystallised in an orthorhombic phase, exhibiting T c above room temperature [11].…”

“…The different magnetic interactions possible in LCFO compounds are Fe-O-Fe (AFM), Co-O-Co (AFM) and Co-O-Fe (FM) [3]. The ferromagnetic interaction of the LCFO compound is due to the 180 • Fe-O-Co superexchange interaction [10]. A large antisite disorder is introduced in perovskites, calcined at higher temperatures resulting in disruption of magnetic exchange paths and hence an increase in antiferromagnetic interactions in the compound [8,19,20].…”