Mössbauer study of Ba2Ti2Fe2As4O

Abstract

A superconductive Ba2Ti2Fe2As4O oxypnictide sample was synthesized following a solid-state reaction route. X-ray diffraction followed by Rietveld analysis was used for checking the phase content. 57Fe Mössbauer spectroscopy in transmission geometry was used for characterizing the hyperfine parameters of the iron site. Ba2Ti2Fe2As4O is paramagnetic at least down to 77 K in contrast to the BaFe2As2 parent phase, which exhibits a spin-density order below ∼140 K. Fitting the isomer shift and spectral absorption data with the Debye model yielded Debye temperatures of 280–320 K.