title: Controlled synthesis of Mn3O4 nanoparticles in ionic liquids.
abstract: This work describes a simple one-step synthesis of Mn3O4 nanoparticles by thermal decomposition of [Mn(acac)2] (acac = acetylacetonate) using imidazolium ionic liquids (ILs) and a conventional solvent, oleylamine, for comparison. The Mn3O4 nanoparticles were characterized by XRD, ATR-FTIR, TEM, Raman, UV/VIS and magnetometry techniques. The addition of 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide IL (BMI·NTf2) yielded a smaller particle size (9.9 ± 1.8 nm) with better dispersion and more regular sizes than synthesis using oleylamine as the solvent (12.1 ± 3.0 nm). The complete conversion of the precursor to Mn3O4 nanoparticles occurred after 96 h at 180 °C for the reaction performed in BMI·NTf2. However, under these reaction conditions in oleylamine, no precursor was detected, but two different phases were observed: a major phase corresponding to Mn3O4 and a minor phase corresponding to MnO2. Magnetometry revealed that Mn3O4 nanoparticles synthesized in either oleylamine or BMI·NTf2 exhibited ferrimagnetic behavior at low temperatures, whereas they were paramagnetic at room temperature. As expected, the blocking temperature and the coercivity decreased with the size of nanoparticles. Our results demonstrate that reaction conditions such as time, and the nature of the ionic liquid play important roles in determining the size of Mn3O4 nanoparticles.
authors: Laboratório de Catálise Molecular (LCM), Instituto de Química, Universidade Federal do Rio Grande do Sul (UFRGS), P.O. Box 15003, 91501-970, Porto Alegre, RS, Brazil. jairton.dupont@ufrgs.br.
authors: Roberta
authors: R
authors: Bussamara
authors: Wellington W M
authors: WW
authors: Melo
authors: Jackson D
authors: JD
authors: Scholten
authors: Pedro
authors: P
authors: Migowski
authors: Graciane
authors: G
authors: Marin
authors: Maximiliano J M
authors: MJ
authors: Zapata
authors: Giovanna
authors: G
authors: Machado
authors: Sérgio R
authors: SR
authors: Teixeira
authors: Miguel A
authors: MA
authors: Novak
authors: Jairton
authors: J
authors: Dupont