Crystal structure of LaSr3Fe3O9 and its phase relation with LaSr3Fe3O10

Abstract The Ruddlesden-Popper phase LaSr 3 Fe 3 O 10 and its reduced derivatives with nominal composition LaSr 3 Fe 3 O 10– x , with 0  x 3 Fe 3 O 9 ( x = 1) phase is described. The LaSr 3 Fe 3 O 10-δ phase prevails for x 3 Fe 3 O 9± e prevails for x  > 0.85. The phases are separated by a two-phase region 0.51  x 3 Fe 3 O 9 is described. LaSr 3 Fe 3 O 9 takes a layer like RP3 type structure with features of the brownmillerite structure in the triple perovskite type slabs; unit cell dimensions a  = 28.7562(13) A, b  = 5.5280(2) A, c  = 5.4583(2) A, space group Cmcm . LaSr 3 Fe 3 O 9 is an antiferromagnet with T N  > 350 K and with a G-type magnetic structure, magnetic space group P C bcm . Based on unit cell volume considerations, local oxygen vacancy ordering schemes are suggested.