Evolution of the crystal structure of YMn2-xFexO5 due to substitution of iron for manganese

YMnFeO5 is a ferrimagnet below 165 K [1]. Its crystal structure is derived from that of the ferromagnetic and low-temperature ferroelectric YMn2O5 by occupation of the Mn position possessing pyramidal oxygen environment with Fe; the other Mn site is coordinated by oxygen in an octahedral manner. Powder samples for x = 0, 0.25, 0.5, 1 [2] were inspected by X-ray powder diffraction and EXAFS, single crystals (x = 0.07, 0.25) by single-crystal X-ray diffraction methods. The structure data show a significant displacement of Fe within the oxygen pyramid, while the Mn position remains nearly constant with respect to the surrounding oxygen atoms. All-electron density-functional calculations in the LSDA+U approximation for the x = 1 compound [3] are in good agreement with the collinear, commensurate ferrimagnetic ordering of the magnetic moments as proposed in [1]. [1] Munoz, A. et al., Chem. Mater. 16, 4087 (2004); [2] all materials prepared by D. Souptel at IFW Dresden; [3] FPLO: Koepernik, K. et al., Phys. Rev. B 59, 1743 (1999).