Structural, optical, and magnetic properties of Fe-doped In 2 O 3 nanocubes
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-Ping Zenga) and Dongliang Jiang Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People’s Republic of China
Zhongming Ren and Weili Ren Department of Materials Science and Engineering, Shanghai University, Shanghai 200072, People’s Republic of China
Junhu Wang and Tao Zhang State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People’s Republic of China (Received 27 September 2007; accepted 9 April 2008)
Fe-doped In2O3 nanocubes were synthesized by a solvothermal method. The lattice constant a decreases linearly as Fe doping concentration increases, and Raman scattering measurement proves the incorporation of Fe ions into the In2O3 crystal lattice. Mössbauer spectra show the presence of mixed valence of Fe ions instead of Fe3O4, while the sample is superparamagnetic. The products with an average diameter of 80 nm have a single-crystalline phase and appear as a square shape. Magnetic measurements confirm the superparamagnetic properties of the nanocubes, and electron paramagnetic resonance studies indicate Fe ions occupy different sites in the In2O3 matrix.
I. INTRODUCTION
Diluted magnetic semiconductors (DMSs) with Curie temperatures (Tc) above room temperature have stimulated much research interest because of their promising applications in spintronic devices.1,2 In particular, transition-metal-doped III-V and II-VI semiconductors appear to be promising candidates and are currently receiving intense theoretical as well as experimental attention.3 A key component to exploiting DMSs is that the host matrices should have wide band gap, i.e., they should be transparent for visible light and able to be heavily doped with n-type carriers.4 Among them, In2O3 is an n-type semiconductor and of interest for its high electrical conductivity as well as its high transparence.5 So far, some efforts have been made to explore the synthesis and magnetic properties of transition metal (TM)-doped In2O3 thin films and bulks samples.6–10 Meanwhile, pure In2O3 nanocrystals with well-defined shapes have attracted in-
a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2008.0332 J. Mater. Res., Vol. 23, No. 10, Oct 2008
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creasing attention because of their size- and shapedependent properties.11–15 Because nanoscale DMSs are key components of spintronic devices,1,16 it is imaginable that shape, size, and magnetic properties as well as controllable growth of In2O3 DMS nanomaterials might contribute to both fundamental research and practical applications. In this work, single-crystalline and nearly monodisperse Fe-doped In2O3 nanocubes were synthesized through a simple method, and their magnetic properties were investigated.
II. EXPERIMENTAL PROCEDURES
Fe-doped In2O3 nanocubes were prepared by a simple solvothermal method. Starting materials of In(NO3)3⭈4.5H2O, Fe(NO3)3⭈9H2O, NaOH, and methanol were analytical grade. In a typical procedure, 0
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