Structure of the polymer-ferromagnetic nanoparticles composite
M. Ławecka*, M. Leonowicz*, M. Kopcewicz**, A Ślawska-Waniewska***, J. Kozubowski****, G.I. Dzhardimalieva*****, A.S. Rosenberg*****, A. Pomogailo***** *Politechnika Warszawska, Wydział Inżynierii Materiałowej, ul. Wołoska 141, 02-507 Warszawa **Instytut Technologii Materiałów Elektronicznych, ul. Wólczyńska 133, 01-919 Warszawa ***Polska Akademia Nauk, Instytut Fizyki, al. Lotników 32/46, 02-668 Warszawa ****Politechnika Warszawska, Wydział Inżynierii Materiałowej, ul. Narbutta 85, 02-524 Warszawa *****Institute of Problems of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka, Russia
Annals 2 No. 5, 2002 pages 404-408
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abstract Thermal transformation of metal - containing monomers is an unique technique, which allows producing nano-sized particles stabilized in a polymer matrix. This method involves solid state polymerisation of the initial monomer followed by decarboxylation of the metal - containing fragments of polymers. Metal formed in the last reaction can be oxidized by CO2 or H2O. The composite material can be in a form of MOr(CH2CHCOO)p-x(CH2CH)x(CHCHCOO)q-y(CHCH)y, where M is transition metal. The composition of the composite material depends on the temperature and time of thermal decay. In the present study the formation and structure of nanocomposites processed by thermolysis of the complex: [Fe3O(CH2CHCOO)6OH][Co(CH2CHCOO)2]1.5• 3H2O has been investigated. The crystalline phases, which were found in the fully processed material, at 643 K, were: CoO, CoFe2O4, Fe3O4 and had mean particle size of about 30 nm (Figs 1-5). In the intermediate stages of the thermolysis iron was present in a form of FeIII (trivalent low-spin iron), Fe2+ (divalent high- -spin iron) and Fe3O4 (Tabs 1, 2). The coercivity and remanence were measured versus temperature in the range of 5÷300 K, in 1.1 T applied field. The MHc and Mr, decreased showing room temperature values of 0.038 T and 7.49 mT, for coercivity and remanence, respectively (Figs 6-9). At temperatures below 200 K the hysteresis loops were asymmetrical and opened.