Local structures of Sr2FeMnO5+y (y=0, 0.5) and Sr2Fe1.5Cr0.5O5 from reverse Monte Carlo modeling of pair distribution function data and implications for magnetic order

► No long range ordering of oxygen vacancies, but short range order is present. ► No short range Fe/Mn order but short range Fe/Cr order is present. ► Fe tends to have lower coordination numbers while Mn and Cr have higher ones. ► Local bond distances and bond angles have been determined. ► Local structures can help explain long range magnetic ordering behavior.