Synthesis and Properties of Magnetic Ceramic Nanoparticles Monica Sorescu, Duquesne University, DMR Outcome Researchers in Duquesne University showed the magnetic ceramic nanoparticles can be produced through simple high energy ball- milling of transition metal oxides and α-Fe 2 O 3. Impact/The as-synthesized magnetic ceramic benefits nanoparticles showed various thermal, magnetic, and electronic properties, of interest in water splitting catalysts, gas sensors, semiconductors, and magnetic materials. Explanation The thermal behavior of hematite was altered due to the solid-solid interaction and ion substitutions in lattice. The formation of solid solution or the formation of perovskite depends on whether solid state reaction occurs. The magnetic phase evolutions were monitored through Mössbauer spectroscopy, which can be used to interpolate the growth mechanism of nanocomposite. The band gap energy of ceramic nanoparticles can be tuned precisely through controlling the duration of ball-milling time and the choice of transition metal oxides. Mössbauer spectra of In 2 O 3 -Fe 2 O 3 solid solution (left, mainly paramagnetic) and LaFeO 3 perovskite (right, mainly antiferromagnetic) SEM images of In 2 O 3 -Fe 2 O 3 solid solution (left) and LaFeO 3 perovskite (right) with big agglomerates consisting of nanoparticles

Synthesis and Characterization of Indium Oxide Doped Hematite xIn 2 O 3 ∙(1-x)  -Fe 2 O 3 Solid Solution Monica Sorescu, Duquesne University, DMR In 2 O 3 -Fe 2 O 3 solid solution synthesized through mechanochemical activation method showed various physical and chemical properties. The development of these properties is controlled by ion substitution effects [1] : (1) In 3+ substitutes Fe 3+ in Fe 2 O 3 lattice, which causes the decrease in the strength of hyperfine magnetic field and the increase in the band gap energy of Fe 2 O 3, respectively, (2) Fe 3+ substitutes In 3+ in In 2 O 3 lattice. Therefore, these findings can be used to predict band gap energy variation and magnetic properties of uninvestigated solid solutions formed between Fe 2 O 3 and M 2 O 3, which are widely used in magnetic materials and water splitting catalyst for energy harvesting. Prof. Monica Sorescu next to a Mössbauer spectrometer used to measure the magnetic properties of synthesized nanoparticles at atomic resolution scale 1. Monica Sorescu et al., Mechanochemical synthesis and characterization of xIn 2 O 3. (1-x)α-Fe 2 O 3 nanostructure system. Journal of Materials Science, 46 (2011)

Investigation of Growth Mechanism of LaFeO 3 Perovskite through Mechanical Ball Milling of Lanthanum and Iron Oxides Monica Sorescu, Duquesne University, DMR LaFeO 3 perovskite can be produced through ball milling the mixture of Fe 2 O 3 and La 2 O 3 at room temperature. The growth mechanism was investigated through XRD and Mössbauer spectroscopy [1] : (1) The grain sizes of both La 2 O 3 and Fe 2 O 3 decrease with the increase in ball milling time, (2) La 2 O 3 and La(OH) 3 phases coexist under the ball milling process, indicating that either La 2 O 3 or La(OH) 3 can be used to produce LaFeO 3, (3) The formation of LaFeO 3 phase was mainly caused by the La 3+ substitution of Fe 3+ in Fe 2 O 3 lattice. Therefore, these findings can be used to direct the synthesis of other Fe-based perovskites through mechanochemical activation. 1. Monica Sorescu et al, Investigation of LaFeO 3 perovskite growth mechanism through mechanical ball milling of lanthanum and iron oxides. Journal of Materials Science, 46 (2011) Figure 1 Phase evolution of LaFeO 3 perovskite during ball milling process