Magnetic properties of nanostructured ferromagnetic FeCuNbB alloys revealed by a novel method for evaluating complex Mossbauer spectra

A novel method for analysing complex Fe-57 Mossbauer spectra has been succe ssfully applied to nanostructured Fe86-xCu1NbxB13 (x = 5, 7). This method p rovides an objective model describing the measured spectra. This model cons ists of the largest meaningful number of lines, given by the 'quality' of t he measured spectrum, i.e. by the criterion that all line parameters should be well defined. Using this method the temperature dependence of the mean hyperfine fields and the fractions of Fe atoms in different sites of the Fe CuNbB samples are derived in the temperature range from 300 K to 700 K. In contrast to conventional methods for determining the hyperfine field distri butions in magnetic alloys this approach allows us to evaluate the resultin g hyperfine field distributions with indication of their mean-square deviat ions. The analysis results in detailed information about the iron nanograin s, the amorphous residual phase and the so-called interface zone.