Evolution under thermal annealing of Mn-doped Iron Disilicides obtained by Ball

J. MARTINEZ, J. RUNCO, S.M. COTES, M.A. TAYLOR AND J. DESIMONI

Foz do Iguazu

Conferencia; XIV International Conference on Hyperfine Interactions and XVIII International Symposium on Nuclear Quadrupole Interactions; 2007

The strong and continual interest in the iron disilicides, with a wide spectrum of physical properties, rests on the fundamental issues related to the stability of the phases, growth kinetics, interface structure and on the technological applications to microelectrocnics, thermoelectrics, photovoltaics and optoelectronics. Phases obtained in the Fe-Si system are extremely depending on the experimental conditions of synthesis. Non-equilibrium processing techniques like mechanical alloying allow the formation of stable and metastable phases at room temperature. Phase formation in the Mn doped iron disilicide system Fe1−xMnxSi2 with 0.00  x  0.24 was studied using X-ray diffraction and Mossbauer spectroscopy. Samples were prepared at room temperature under Ar atmosphere by the simultaneous milling of the pure elements followed by an annealing at 1123K at 1× 10−7 Torr. In agreement with the XRD results, for the as milled samples, the obtained set of hyperfine parameters supports the coexistence of b-FeSi2, a-FeSi2 and e-FeSi. While the diffraction and Mossbauer results only show the presence of b-FeSi2 and of a-FeSi2 after annealing.The relative fraction of the last one increases with the Mn content. Segregation of Fe was not observed.