Room-temperature ferromagnetism in Ti 1− x V x O 2 nanocrystals synthesized from an organic-free and water-soluble precursor
ABSTRACT Ti1−xVxO2 nanocrystals were prepared by employing a novel and water-soluble precursor via hydrothermal method, and the microstructure and magnetic properties have been investigated. All the samples belong to a pure anatase structure and exhibit room-temperature ferromagnetism (RTFM) without any trace of vanadium oxides or clusters. After V doping, the anatase structure is retained, while crystal growth is restrained. The homogenous distribution of V, in V4+ chemical state, in TiO2 lattice is confirmed by X-ray powder diffraction (XRD), energy-dispersive X-ray spectra (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. Ferromagnetism in Ti1−xVxO2 is revealed to be highly dependent on the V content and defect concentrations. Furthermore, the annealing study in various atmospheres indicates that the oxygen vacancies and interstitials play a crucial role in inducing ferromagnetism in Ti1−xVxO2 system, and the origin of RTFM can be explained by bound magnetic polaron model.
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ABSTRACT: The state and outlook of works on the creation of ferromagnetic semiconductor materials for applications in spin electronics and informatics units are considered. The obtained results on promising ferromagnetic semiconductor material classes—doped elementary semiconductors, AIIIBV compounds, and semiconductor oxides—are given. Unsolved problems in the considered area are indicated and possible ways of their solutions are outlined.Russian Microelectronics 12/2012; 41(8). DOI:10.1134/S1063739712080136
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ABSTRACT: V-doped TiO2 nanoparticles were synthesized by sonochemical process using titanium isopropoxide as a titanium source, vanadyl acetylacetonate as a dopant source. Sonication was conducted using sonic horn operated at 20 kHz for 20 min until the completely precipitated product was reached. The as-synthesized precipitates with various vanadium dopant (1–5 mol %) were calcined at 500–1000 °C for 4 h. The relevant physical properties of the nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). The anatase phase TiO2 nanoparticles can be synthesized by sonochemical process. Post calcinations process results in the anatase-to-rutile phase transformation and the enhancement in crystallinity with increasing temperature. The results also indicate good incorporation of V ions in TiO2 lattices and significant effect of V dopant on alternation of interplanar spacing of TiO2.Ceramics International 05/2013; 39:S389–S393. DOI:10.1016/j.ceramint.2012.10.100 · 2.09 Impact Factor