Počet záznamů: 1  

Alternating magnetic field energy absorption in the dispersion of iron oxide nanoparticles in a viscous medium

  1. 1.
    0450283 - UFM-A 2016 RIV NL eng J - Článek v odborném periodiku
    Smolkova, I.S. - Kazantseva, N.E. - Babayan, V. - Smolka, P. - Parmar, H. - Vilcakova, J. - Schneeweiss, Oldřich - Pizúrová, Naděžda
    Alternating magnetic field energy absorption in the dispersion of iron oxide nanoparticles in a viscous medium.
    Journal of Magnetism and Magnetic Materials. Roč. 374, JAN (2015), s. 508-515. ISSN 0304-8853
    Institucionální podpora: RVO:68081723
    Klíčová slova: Iron oxide nanoparticles * Coprecipitation * Magnetic interactions * Specific loss power * Hyperthermia
    Kód oboru RIV: BM - Fyzika pevných látek a magnetismus
    Impakt faktor: 2.357, rok: 2015

    Magnetic iron oxide nanoparticles were obtained by a coprecipitation method in a controlled growth process leading to the formation of uniform highly crystalline nanoparticles with average size of 13 nm, which corresponds to the superparamagnetic state. Nanoparticles obtained are a mixture of single-phase nanoparticles of magnetite and maghemite as well as nanoparticles of non-stoichiometric magnetite. The subsequent annealing of nanoparticles at 300 degrees C in air during 6 h leads to the full transformation to maghemite. It results in reduced value of the saturation magnetization (from 56 emu g(-1) to 48 emu g(-1) but does not affect the healing ability of nanoparticles. A 2-7 wt% dispersion of as-prepared and annealed nanoparticles in glycerol provides high healing rate in alternating magnetic fields allowed for application in magnetic hyperthermia; however the value of specific loss power does not exceed 30 W g(-1). This feature of heat output is explained by the combined effect of magnetic interparticle interactions and the properties of the carrier medium. Nanoparticles coalesce during the synthesis and form aggregates showing ferromagnetic-like behavior with magnetization hysteresis, distinct sexes on Mossbauer spectrum, blocking temperature well about room temperature, which accounts for the higher energy barrier for magnetization reversal. At the same time, low specific heat capacity of glycerol intensifies heat transfer in the magnetic dispersion. However, high viscosity of glycerol limits the specific loss power value, since predominantly the Neel relaxation accounts for the absorption of AC magnetic field energy.
    Trvalý link: http://hdl.handle.net/11104/0253348