Structural and Magnetic Properties of Prussian Blue Analogue Molecular Magnet Fe_(1.5)Cr(CN)_6·mH_2O

摘要

Molecular magnets, based on Prussian blue analogues, Fe_(1.5)[Cr(CN)_6]·mH_2O have been synthesized in the bulk as well as nanoparticle forms using a co-precipitation method, and their structural and magnetic properties have been investigated using x-ray diffraction (XRD) Mossbauer spectroscopy and dc magnetization. The XRD study confirms the single phase crystalline and nanoparticle nature of the compounds with a face centered cubic (fcc) structure of space group Fm3m. The values of lattice constant are found to be ～10.18(5) A and ～9.98(9)A, for the bulk and nanoparticle samples, respectively. The dc magnetization shows a Curie temperature (T_C) of ～17 K and ～5 K for the bulk and nanopartcile samples, respectively. The Mossouber spectroscopy reveal that the compound shows spin flipping from the high spin (HS) Fe (Cr~(III)-C≡N-Fe~(II)) to low spin (LS) Fe~(II) ions (Cr~(III)-N≡C-Fe~(II)). Moreover, the T_C and the HS state of the Fe ions decreases (converts to its LS states) with time as well as in the nanoparticle form compared to bulk.