Mössbauer study of Ba₂Ti₂Fe₂As₄O

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.