Microwave Combustion Synthesis of Silver Doped Lanthanum Ferrite Magnetic Nanoparticles

Abstract

ExpErImEntal dEtaIlsAll the chemicals used were of A.R. grade. The salt precursors i.e. lanthanum nitrate (La(NO 3 ) 3 .6H 2 O) and ferric nitrate (Fe(NO 3 ) 3 .9H 2 O) and glycine (NH 2 CH 2 COOH) as a fuel were from Loba Chemie, India, while silver nitrate (AgNO 3 ) was from Qualigens, India. Lanthanum ferrite (LaFeO 3 ) was synthesized by initially mixing the precursor salts together in stoichiometric amounts i.e. 1:1 equimolar ratio (0.08 M each) followed by addition of glycine as fuel (0.26 M). To this, were added ~50 ml of double distilled water. The stoichiometric composition of the mixture was calculated based on oxidizing valency of metal nitrates and reducing valency of glycine 19 . Silver doped samples both at A (La) site and B (Fe) site i.e. La (1-x) Ag x FeO 3 and LaFe (1-x) Ag x O 3 were prepared by partial substitution of host atoms (La and Fe) by varying the concentration of added silver (x = 0.25, 0.50, and 0.75). The resulting mixtures (for undoped and doped perovskites) were stirred for few minutes at room temperature and subjected to evaporation on a hot plate so as to obtain a gel. The gels were subjected to microwave power (0.1-0.9 kW) using a domestic microwave oven (MG-555F Model) for auto combustion and the resulting products were cooled to room temperature. Pure phase products both, for pure and silver doped samples were obtained at 0.42 kW microwave power. During synthesis, the microwave combustion synthesis of silver doped lanthanum Ferrite magnetic nanoparticles ) and silver doped LaFeO 3 powders were synthesized by a single step microwave combustion route using nitrates as precursors and glycine as a fuel. XRD analysis indicated the formation of cubic phase with the dopant peaks at 2θ values of 38.3°, 44.1°, and 64.4° apart from the peaks corresponding to LaFeO 3 . As observed from the transmission electron micrographs, LaFeO 3 exhibits particles with a larger size (mean size ~57 nm), significant decrease in particle size is observed for silver doped samples. The magnetic measurements reveal weak ferromagnetic nature of LaFeO 3 , while silver doped samples are ferromagnetic in nature. Lanthanum silver ferrite (x = 0.25, A site) shows maximum coercivity (Hci = 480.96 G) with hysteresis loop at room temperature which is a clear sign of ferromagnetic ordering. The S shape of the curve implies the presence of domain wall movements in nanoparticles. Thermogravimetric analysis of the samples show stable behavior of the products.

La0.8Bi0.2FeO3 Perovskite-Type: High-Performance of Photocatalytic Degradation of Ortho-Toluidine Blue Under Visible Light Irradiation

“…Additionally, we observe that there are two closely bands, the first of which is at 1385 cm -1 and the second at 1485 cm -1 . They are attributed to NO 3and N-H respectively, and both come from reacted precursor raw materials; they are neighbors and weak [40]. The La/Fe-O bending vibration modes do not change in frequency with increasing Bi content up to x=0.6, confirming that there has been no lattice deformation and, consequently, no changes in the length of the La/Fe-O bond, as supported by the XRD analysis.…”