Mossbauer studies of nanocrystalline ZnFe2O4 particles prepared by spray pyrolysis method

Abstract

This paper reports the synthesis and characterization of nanoparticles of Zn Fe2O4 by spray pyrolysis method. XRD studies indicates that the particle formed are ultra fine (20 nm) associated with strain. The particle size is confirmed by TEM analysis. The room temperature Mossbauer spectrum shows only a doublet which could be indicative of either paramaganetic or superparamagnetic phase. The value of isomer shift is in the range 0.34 +/- 0.01 mm/s while quadruple splitting is in the range 0.48 +/- 0.01 mm/s. A series of low temperature studies has been performed and the spectra obtained at 20 K and 5K show the presence of two well resolved sextets, which are attributed to the Fe3+ ion in the tetrahedral and octahedral sites of the spinel structure. The application of external magnetic field yields a better fitting resolution of the sub spectra between A and B sites. The temperature dependant and in-field measurements yielded valuable insights about magnetic phase (superparamagnetic), local cation distribution among A sites and B sites, inversion parameter (delta = 0.74), canted spin alignment (psi(A) = 29.58, psi(B)= 48.46) and the blocking temperature (T-B= 50 K).