Browsing by Author "Samuneva B.I."

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    Characterization of superparamagnetic MgxZn1-x Fe2O4 powders
    (2007-03-01) Kassabova-Zhetcheva V.D.; Pavlova L.P.; Samuneva B.I.; Cherkezova-Zheleva Z.P.; Mitov I.G.; Mikhov M.T.
    Structural and magnetic properties of MgxZn1-x Fe2O4 powders have been studied with respect to the application for thermal cancer therapy (magnetic hyperthermia). MgxZn1-xFe2O4 (x = 0.1-0.5) powders with particle sizes between 5 and 8 nm were produced by citrate method. The X-ray diffraction patterns of the samples correspond to a spinel phase. The lattice constant and the volume of the elementary cell increase when x changes from 0.1 to 0.5. The FTIR-spectra ascertain the spinel phase formation. The Mossbauer studies reveal the presence of extremely small particles, which undergo superparamagnetic relaxation at room temperature. The core-shell model has been applied to explain quadruple doublets. The quadruple splitting at ``shells`` is bigger than those at ``cores`` whereas the isomer shifts remain close. Magnetic studies confirm the presence of extremely small particles that behave as superparamagnetic ones. © Versita Warsaw and Springer-Verlag Berlin Heidelberg 2006.