Papers by Keyword: Mössbauer Effect

Abstract: The Mg_1-xZn_xFe₂O₄ (x = 0, 0.2, 0.44, 0.5, 0.6) ferrite nanopowders of the spinel structure obtained by the sol-gel autocombustion (SGA) have been investigated using the X-ray diffraction and Mössbauer methods. The proofs were revealed verifying the potential occurrence of structural heterogeneity as solid solutions of various compositions of ferrites can be observed in a single phase system. In case of magnesium–zinc replacement, structural components occur, having different distribution of ferrum cations in crystallographic positions of the spinel lattice. The abnormal strength of nuclear effective fields is the indicator thereof. In addition, paramagnetic and superparamagnetic components were discovered there as well. This effect cannot be observed in the ferrite synthesis by the ceramic method.

Abstract: The studies of X-ray diffraction, magnetization, magnetocaloric effect, and 57Fe Mössbauer spectra have been performed in a bulk sample of RhFe compound synthesized under high pressure. It have been found that RhFe has fcc-type of crystal structure at room temperature and, shows the first order magnetic transition from the antiferromagnetic-like to ferromagnetic state close to 338 K at 5T magnetic field. This type of behavior has been verified by differential scanning calorimetry, magnetization and Mössbauer techniques. The irreversible transition from antiferromagnetic to stable ferromagnetic state has been observed after heating of sample up to 573K.

Abstract: A first-order metamagnetic transition from antiferromagnetic to ferromagnetic state in La (Fe0.88Al0.12-xSix) compounds was investigated using Mossbauer effect. The exchange-related clusters in the ferromagnetic and antiferromagnetic state are shown to exist. The influence of Si on magnetic structure is observed.

Abstract: The Mössbauer spectra of PdMnxFe1-x alloys obtained at 80 K and at 300 K were studied in the 0.2 < x < 0.8 concentration range, in which there realizes a microinhomogeneous multiphase medium formed by isostructure phases of the constituent compositions: ferromagnetic PdFe (ТС=730 К) alloy undergoing atomic ordering and antiferromagnetic PdMn (TN=815 К) intermetallic compound. Magnetic properties studies evidence the presence of a third presumably noncollinear phase with its own ordering temperature lying below the Curie temperature of the ferromagnetic phase in the 0.2 < x < 0.8 concentration range. The Mössbauer spectra at 300 K exhibit a doublet for antiferromagnetic alloys (x > 0.8) and a sextet at Hhf ~350 kOe for ferromagnetic alloys (x < 0.2). In the intermediate concentration range several peaks 0 < Hhf < 350 kOe have been observed in the P(Hhf) curves, which result from microinhomogeneous multiphase state.