UV pulsed laser deposition of magnetite thin films

Phosphate Adsorption Properties of Magnetite-Based Nanoparticles

“…[72][73][74][75] The deviation from 0.50 is generally attributed to a superstoichiometry in oxygen or cationic vacancies; there would be oxidation of Fe 2+ on the B site in Fe 3+ accompanied by vacancies of formation, giving the general formula: Fe 3+ A [Fe 2.5+ 2-6δ Fe 3+ 5δ 0 δ ] B O 4 2-. Calculations of the stoichiometry deviation from the relative subspectral area with the formula reported by Voogt et al 76 and with that of Parame ˆs et al 77 give for both adsorptions a similar deviation δ ) 0.08 in Fe 3-δ O 4 , leading thus to a general formula of Fe 2.92 O 4 . The values of isomer shift lead to an estimate of the Fe valence state and, then, to composition.…”

Hydrothermal Synthesis of Monodisperse Magnetite Nanoparticles

“…A [Fe 2.5+ 2-6δ Fe 3+ 5δeδ ] B O 4 2-. Calculations of the stoichiometry deviation from relative subspectral area with two different reported formulas, δ ) 0.063 in Fe 3-δ O 4 28 and δ ) 0.057 in Fe 3-δ O 4 , 30 give a general formula of Fe 2.94 O 4 . The values of the isomer shift lead to an estimate of the Fe valence state, i.e., the Fe content; assuming the isomer shift of Fe 3+ tetra , Fe 3+ octa , and Fe 2+ octa at 0.25, 0.40, and 1.00 at 300 K, and 0.40, 0.54, and 1.15 at 77 K, respectively, one obtains Fe 2.95 O 4 .…”

“…Moreover, controlling the synthesis conditions is a critical point, because the properties of nanoparticles are found to vary with synthesis methods. ,,− The variations in magnetic properties were assigned to different parameters, such as cationic distribution and vacancies, nonstoichiometry, spin canting, or surface contribution due to the nanometric size. ,,− Reports on the synthesis of magnetite nanoparticles with controlled grain sizes and careful characterizations have been unable to choose between these explanations.…”

“…19,20,[24][25][26][27][28][29] The variations in magnetic properties were assigned to different parameters, such as cationic distribution and vacancies, nonstoichiometry, spin canting, or surface contribution due to the nanometric size. 23,24,[30][31][32][33][34][35] Reports on the synthesis of magnetite nanoparticles with controlled grain sizes and careful characterizations have been unable to choose between these explanations. We report here the synthesis of magnetite nanoparticles, with an average grain size of 39 ( 5 nm, a controlled stoichiometry, and a ferrimagnetic behavior at room temperature, by using a hydrothermal process.…”

Síntese e caracterização de nanopartículas magnéticas: Aplicação como vetores de liberação de óxido nítrico

“…No caso dos processos físicos, podemos citar, por exemplo, condensação por gás inerte [10], plasma [11], sputtering de íons [12], e ablação por laser a partir de ma-1 teriais macroscópicos [13]. Os processos químicos para obtenção de nanopartículas ocorrem a partir de átomos e moléculas que as formam via redução química [14], método sol-gel [15], sonoquímica [16], método solvotérmico [4], decomposição térmica [17] e coprecipitação [18].…”