Solventless synthesis and characterization of α-Fe, γ-Fe, magnetite and hematite using iron(III)citrate

Effect of reaction protocol on the nature and size of iron oxide nano particles obtained through solventless synthesis using iron(II)acetate: structural, magnetic and morphological studies

“…On the other hand, in case of FA2, the sextet S1 can be assigned to iron in magnetite, whereas the sextet S2 represents iron in hematite phase [16,18,41]. The population ratio of these two sites is ~ 2:3.…”

“…In magnetite at ~ 123 K, a charge-ordering transition (Verwey transition) occurs when an ordering of Fe 3+ and Fe 2+ ions within the octahedral sites occurs and a drop in magnetization at the transition temperature is the signature of magnetite [13,14]. On the other hand, at ~ 263 K, hematite exhibits a weak ferromagnetic to antiferromagnetic transition (Morin transition) owing to rearrangement of spins to antiparallel fashion along the rhombohedral (111) axis from a canted spin arrangement with respect to the basal (111) plane [15][16][17]. These magnetic phases of iron oxide along with subphases are very accurately detected by the application of Mӧssbauer spectroscopy [16,18].…”

“…On the other hand, at ~ 263 K, hematite exhibits a weak ferromagnetic to antiferromagnetic transition (Morin transition) owing to rearrangement of spins to antiparallel fashion along the rhombohedral (111) axis from a canted spin arrangement with respect to the basal (111) plane [15][16][17]. These magnetic phases of iron oxide along with subphases are very accurately detected by the application of Mӧssbauer spectroscopy [16,18].…”

“…There are several methods for preparing iron oxide nanoparticles, e.g., solventless thermal decomposition of iron-containing compounds [21], electrochemical deposition [22], co-precipitation [23], ultrasound irradiation [24], solvothermal method [25], microemulsion [26] and hydrothermal method [27]. Out of these methods, solventless thermal decomposition of iron-containing molecular materials is the most easy and practical technique for synthesis of iron oxide nanoparticles as this method neither requires any special instrument nor involves complicated reaction steps, and, moreover, this method provides a good control over the homogeneity, composition, purity, phase and microstructure of the decomposed products [14,16,20,28]. Selection of a proper organo-iron molecular precursor with comparatively low decomposition temperature and a rational reaction protocol may result the desired magnetic iron oxide nanoparticles via solventless thermal decomposition route.…”

“…The reaction mechanism involved as well as the energy required to initiate the decomposition reaction can be obtained by the reaction kinetic study [29,30]. In continuation of our earlier attempts [14,16] to prepare iron oxide nanoparticles, presently we report the synthesis of pure magnetite and hematite nanoparticles (size ~ 20 nm) using iron(II)acetate as the sole precursor under different reaction protocols. The materials synthesized were characterized by different physical techniques like FT-IR, powder XRD and 57 Fe Mӧssbauer spectroscopy where the morphology and compositional analysis were studied by SEM/TEM and EDX, respectively.…”