Effect of particle size and alloying with different metals on 57Fe Mössbauer spectra

Abstract

Iron nanoparticles of various sizes have been synthesized using the chemical route which involves the preparation of iron bipyridine complexes in presence of different capping agents followed by thermal decomposition at 450°C in inert atmosphere. The bimetallic nanoalloys of Fe with Mg and Pd have also been prepared by following the same route. The resulting nanoparticles have been characterized by EDX-RF, XRD, AFM and 57Fe Mossbauer spectroscopy. The appearance of quadrupole doublets in the Mossbauer spectra of Fe nanoparticles indicates the absence of magnetic interaction and variation in parameters is due to the varying particle size. The Mossbauer spectrum of Fe–Mg2 bimetallic nanoalloy shows two doublets indicating the presence of superparamagnetism. The two doublets can be attributed to change in s-electron density of iron resulting from its two neighboring magnesium atoms. Fe–Pd nanoalloy Mossbauer spectrum is characterized by having a superparamagnetic doublet and a ferromagnetic sextet.