AVS 57th International Symposium & Exhibition
    Nanometer-scale Science and Technology Tuesday Sessions
       Session NS-TuP

Paper NS-TuP13
Magnetic Properties of Fe–O Nanonetworks

Tuesday, October 19, 2010, 6:00 pm, Room Southwest Exhibit Hall

Session: Nanometer-Scale Science and Technology Poster Session
Presenter: C.G. Franco, University of Texas at El Paso
Authors: C.V. Ramana, University of Texas at El Paso
C.G. Franco, University of Texas at El Paso
K.B. Karuppanan, University of Texas at El Paso
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Nanostructures of Fe oxides and hydroxides with varying morphologies were prepared in aqueous media by precipitation of iron nitrate and ammonium hydroxide. The synthesis was carried out at room temperature (RT) involving two stages. The first stage is the precipitation of goethite and the second stage corresponds to the structural modification due to acetic acid. Initially, 250 ml of 3.52N NH4OH was added to 250 ml of 1N Fe(NO3).9H2O under magnetic stirring for 30 min at RT. The precipitates were washed with de-ionized water and maintained in water at 1.25N. AcOH was added to obtain three different concentrations: 2.4, 9.1, and 16.7 vol %. Powders were obtained heating the sols at 373 K until dry, and oxides were obtained by heat treatment at 773 K for 2 h. The samples with acetic acid addition show hematite (α-Fe2O3) with average size of 20 nm . Temperature variation of magnetization measurement was carried out for all the samples and the Curie temperature values for the 2.4, 9.1, and 16.7 vol % AcOH added samples were found to be 1004 K, 1024 K and 982 K respectively. Magnetization measurement was carried out at up to the magnetic field of 1000 Oe for 2.4 and 16.7 vol % AcOH added samples at room temperature as well as at higher temperatures. Magnetization value was found not to saturate at 1000 Oe for both the samples. For 16.7 vol % AcOH added sample, the saturation magnetization value at 300 K was calculated from Honda plot (1/H vs M plot) and it is found to be 38 emu/g. Coercive field value was found to be 255 Oe at 300 K. In the case of 2.4 vol% AcOH sample, magnetization measurements were carried out at different temperatures (from 300 K to 800 K) and the coercive field value was found to decrease with increasing temperature (130 Oe to 10 Oe).