. . . . . . . . . .    ANM 2010     3rd International Conference on Advanced Nano Materials     12-15 September 2010 - Agadir, Morocco Back    Abstract ANMM240 FERROMAGNETIC ORDER IN AGED CO-DOPED TIO2 ANATASE NANOPOWDERS A.J. Silvestre 1, L.C.J. Pereira 2, M.R. Nunes 3 and O.C. Monteiro 3 1 Instituto Superior de Engenharia de Lisboa and ICEMS, R. Conselheiro Emídio Navarro 1, 1959-007 Lisboa, Portugal 2 Departamento de Química, Instituto Tecnológico e Nuclear and CFMCUL, Estrada Nacional 10, 2686-953 Sacavém, Portugal 3 Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal . Oxide based diluted magnetic semiconductor (DMS) materials have been a subject of increasing interest due to reports of room temperature ferromagnetism in several systems and their potential use in the development of spintronic devices. However, concerns on the stability of the magnetic properties of different DMS systems have been raised. Their magnetic moment is often unstable, vanishing with a characteristic decay time of weeks or months, which precludes the development of real applications. This work reports on the ferromagnetic properties of two-year-aged Co-doped TiO2 reduced anatase nanopowders with different Co contents up to 10 at.%. Aged samples retain rather high values of magnetization, remanence and coercivity which provide strong evidence for a quite preserved long-range ferromagnetic order. In what concern Co segregation, some degree of metastability of the diluted Co doped anatase structure could be inferred in the case of the sample with the higher Co content. . © nanoAC . . . . . . . . . .

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