  Neutron diffraction and X-ray pair distribution function (XPDF) experiments
were performed in order to investigate the magnetic and local crystal
structures of Ba2FeSbSe5 and to compare them to the average (i.e. long-range)
structural model, previously obtained by single crystal X-ray diffraction.
Changes in the local crystal structure (i.e. in the second coordination sphere)
are observed upon cooling from 295 K to 95 K resulting in deviations from the
average (i.e. long-range) crystal structure. This work demonstrates, that these
observations cannot be explained by local or long-range magnetoelastic effects
involving Fe-Fe correlations. Instead, we found, that the observed differences
between local and average crystal structure can be explained by Sb-5s lone pair
dynamics. We also find, that below the N\'eel temperature (TN = 58 K), the two
distinct magnetic Fe3+ sites order collinearly, such that a combination of
antiparallel and parallel spin arrangements along the b-axis results. The
nearest-neighbor arrangement (J1 = 6 {\AA}) is fully antiferromagnetic, while
next-nearest-neighbor interactions are ferromagnetic in nature.
