Iron Environment Non-Equivalence in Both Octahedral and Tetrahedral Sites in NiFe_2O_4 Nanoparticles: Study Using Mossbauer Spectroscopy with a High Velocity Resolution

摘要

Mossbauer spectrum of NiFe_2O_4 nanoparticles was measured at room temperature in 4096 channels. This spectrum was fitted using various models, consisting of different numbers of magnetic sextets from two to twelve. Non-equivalence of the ~(57)Fe microenvironments due to various probabilities of different Ni~(2+) numbers surrounding the octahedral and tetrahedral sites was evaluated and at least 5 different microenvironments were shown for both sites. The fit of the Mossbauer spectrum of NiFe_2O_4 nanoparticles using ten sextets showed some similarities in the histograms of relative areas of sextets and calculated probabilities of different Ni~(2+) numbers in local microenvironments.