Effect of Pressure on Magnetic Properties of TM3 [Cr(CN)6 ]2 · nH2O Nanoparticles

A. Zentko, M. Zentková, V. Kavečanský, M. Mihalik, Z. Mitróová Institute of Experimental Physics, Slovak Academy of Sciences, 040 01 Košice, Slovak Republic Z. Arnold, J. Kamarád Institute of Physics of the AS CR, v.v.i., Na Slovance 2, 182 21 Prague 8, Czech Republic M. Cieslar Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic and V. Zeleňák P.J. Šafárik University, Moyzesova 11, 04154 Košice, Slovakia

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Received: 9 07 2007;

Effect of pressure on magnetic properties of magnetic nanoparticles, based on Prussian blue analogues, were studied in pressures up to 1.2 GPa. The Mn3 [Cr(CN)6 ]2  · nH2O and Ni3 [Cr(CN)6 ]2  · nH2O nanoparticles were prepared by reverse micelle technique. Transmission electron microscopy images show nanoparticles with average diameter of about 3.5 nm embedded in an organic matrix. The characteristic X-ray peaks of nanoparticles are more diffused and broader. Systems of nanoparticles behave as systems of interacting magnetic particles. The Curie temperature TC is reduced from TC = 56 K for Ni-Prussian blue analogues to TC = 21 K for Ni-nanoparticles system and from TC = 65 K for Mn-Prussian blue analogues to TC = 38 K for Mn-nanoparticles system. One can explain this reduction of the Curie temperature and of the saturated magnetizationμs by dispersion of nanoparticles in an organic matrix i.e. by a dilution effect. Applied pressure leads to a remarkable increase in TC for system of Mn-nanoparticles (ΔTC /Δp = +13 K/GPa) and to only slight decrease in TC for system of Ni-nanoparticles (ΔTC /Δp = -3 K/GPa). The pressure effect follows behavior of the mother Prussian blue analogues under pressure. The increase in saturated magnetization, attributed to compression of the organic matrix, is very small.

DOI: 10.12693/APhysPolA.113.489 PACS numbers: 75.30.Cr, 75.50.Ee, 75.50.Gg, 75.50.Xx