MAGNETIC PROPERTIES AND MEMORY EFFECT IN NICKELCHROMIUM CYANIDE

MAGNETIC PROPERTIES AND MEMORY EFFECT IN NICKEL-CHROMIUM CYANIDE NANOPARTICLES M. 1 Zentková , 1 Institute A. 1 Zentko , 3 Institute Subject: 1 Mihalik , 1 Maťaš , M. S. 3 4 Z. Jagličić , V. Zeleňák Z. 1 Mitróová , M. 2 Maryško , of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, Slovakia 2 Institute 4 Institute J. 1 Kováč , of Physics of the AS CR, v. v. i. , Na Slovance 2, 182 21 Prague 8, Czech Republic of Mathematics, Physics and Mechanics, Jadranska 19, 1000 Ljubljana, Slovenia of Chemistry, P. J. Šafárik University, Faculty of Science, Moyzesova 11, 040 01 Košice, Slovakia comparison of magnetic properties of Ni-PBA powders and Ni-NAP Material: Ni 3 [Cr(CN)6]2. 12 H 2 O, polycrystalline (PBA) and nanoparticles (NAP) prepared by reverse micelle method Method: SQUID magnetometry; Motivation: magnetic interaction among magnetic NAP Experimental: The reverse micelles technique was used for preparation of Cr. III-Ni 2+ cyano - bridged NAP dispersed in an organic matrix. The content of organic surfactants in the samples was estimated to about 22 wt. % (Ni-NAP) by TGA analysis (SETARAM 9 L). The compounds were characterized by IR spectroscopy (Avatar 330) confirming the presence of Ni- based PBA. TEM observations were performed on JEOL JEM 200 FX transmission electron microscope operated at 200 k. V. X-ray diffraction (XRD) powder diagrams were recorded using a Philips X-Pert diffractometer at Cu Kα radiation. XRD pattern and the size distribution of the NAP. Darkfield TEM images shows Ni – NAP in an organic matrix; an average size of Ni – NAP determined from image analysis is 4. 5 nm. Dispersion of Ni-NAP in the organic matrix leads to dilution of the magnetic system resulting in reduction of the Curie temperature from TC = 56 K for ferromagnet Ni–PBA to TC = 22 K. A reduction of TC on dilution is seen from χ’(T) and χ’’(T) on Ni-NAP. The maximum in ZFC curves indicates freezing temperature Tf which is typical for cluster glass-like behavior very frequently observed in PBA below TC. Comparison of magnetization curves of polycrystalline Ni-PBA and Ni-NAP shows the presence of organic matrix. NAP system shows higher value of Mr and Hc than PBA powder systems. Both powder samples behave similarly in paramagnetic region. Acknowledgements: This work was supported by VEGA 2/7184/07 and APVT 51 -031704 projects.