Structure of LaSrFeO 4 : neutron diffraction, Mössbauer spectroscopy and modeling

Mossbauer spectroscopy and neutron diffraction experiments were carried out for study of LaSrFeO4, synthesized by wet chemical method. The data obtained were interpreted on the basis of аb initio quantum-mechanical modeling. The experimental results from Mossbauer spectroscopy and model calculations show that occupational distribution of La and Sr atoms on (4е) Wyckoff positions of I4/mmm space group (confirmed by neutron diffraction) is not random as previously assumed, but predominantly in double layers of either La or Sr. The distribution of each double layer is however random. The quantum mechanical model calculations of La and Sr arrangement along the c-axis explain the presence of two Mossbauer sextets at low temperature despite the unique position of Fe in the unit cell.