Nickel ferromagnetic nanoparticles of different sizes in anisotropic magnetoelastomer materials

LANDA, R. A.; NEGRI, R. M.; PEREZ, O. E.; JORGE, G. A.; ANTONEL, P. S.

Buenos Aires

Congreso; At the Frontiers of Condensed Matter V; 2010

Comisión Nacional de Energía Atómica - Centro Atómico Constituyentes

Magnetoelastomers are dispersions of magnetic particles into an elastomer polymer matrix [1,2].These materials combine magnetic and elastic properties in the same material.In this work, nickel ferromagnetic nanoparticles were synthesized, following Sidhaye et al [3]. The syntheses were performed at different concentrations and temperatures (up to 60º C) in order to explore their influence in the properties of nanoparticles. The X-ray powder diffraction patterns indicate that the formation of Ni nanoparticles is favored at low concentration of reactants and at room temperature. As the concentration of reactants and the temperature of synthesis are increased, formation of hydroxides and oxides nanoparticles of Ni(II) and Ni(III) is observed. SEM images show a significant decrease in the particle size when both the concentration of reactants and temperature of synthesis are increased. VSM (Vibrating Sample Magnetometer) measurements are in good agreement with the results of XRD and SEM. First, in the case of nanoparticles synthesized at room temperature and low concentrations of reactants, a ferromagnetic behavior is observed. Moreover, a saturation magnetization of about 40 emu/g is obtained. Second, with other synthesis conditions, a marked decrease of the saturation magnetization is observed, due to the presence of hydroxides/oxides of Ni(II) and Ni(III). Composites of PDMS (poly-dimethylsiloxane) and nanoparticles synthesized at room temperature were prepared. In the absence of an external magnetic field during curing, composites of uniform distribution of nanoparticles are observed in SEM images. On the other hand, when curing is performed in the presence of an external magnetic field, formation of macroscopic needles oriented along the direction of the magnetic field is observed. Those needles were also observed by SEM, being wider when preparing composites with nanoparticles with higher saturation magnetization. Finally, the composites were characterized by VSM and texture measurements. From those results is concluded that the material have both magnetic and elastic anisotropy. [1] Filipcsei, G.; Csetneki, I.; Szilágyi A.; Zrinyí M.; Adv. Polym. Sci. 2007, 206(1), 137-189. [2] Varga, Z.; Filipcsei , G.; Zrınyí, M. Polymer 2006, 47(1), 227-233. [3] Sidhaye, D. S.; Bala, T.; Srinath, S.; Srikanth, H.; Poddar, P.; Sastry, M.; Prasad, B. L. V. J. Phys. Chem. C. 2009, 113, 3426-3429.