Mössbauer study of YBaCuFeO5+δ: site assignments of the metallic ions

Interplay between Cu and Fe Valences in BaR(Cu0.5Fe0.5)2O5+δ Double Perovskites with R=Lu, Yb, Y, Eu, Sm, Nd, and Pr

“…All previous MoK ssbauer studies on BaR(Cu Fe ) O >B samples revealed an intense component assigned to "ve-coordinated high-spin Fe>, in accordance with the expected Fe valence and the presence of (Cu,Fe)O pyramids in the structure (1}5, 11,15). This was rather straightforward using the experimental isomer shift and saturation "eld values of 0.25}0.35 mm/s and &50 T, respectively.…”

“…Moreover, as the octahedral coordination polyhedron is somewhat #attened resulting in an increased value for the quadrupole coupling constant, the component with the larger eQ C < XX value (Component 2) is assigned to six-coordinated Fe> and the component with the smaller eQ C < XX value (Component 1) to "ve-coordinated Fe>. Earlier high-temperature MoK ssbauer measurements con"rm the assignment of the latter component (4,15). The results of the paramagnetic spectra agree rather well with the corresponding AF spectra, i.e.…”

Layered (Cu,Fe) oxides of double perovskite structure: Correlation between structural and magnetic-property changes inBaY(Cu0.5Nagase1, Lindén2, Miettinen3 et al. 1998Phys. Rev. B19150View full textAdd to dashboardCite

“…The structure of BaY͑Cu 0.5 Fe 0.5 ͒ 2 O 5 has been discussed in two possible space groups: P4mm allowing two different sites for iron and copper ions 14,15 and P4/mmm assuming one single Cu/Fe site. 7 Space group P4mm was suggested by Meyer et al 14 and Pissas et al 15 from Mössbauer spectra of BaY͑Cu 0.5 Fe 0.5 ͒ 2 O 5 and BaR͑Cu 0.5 Fe 0.5 ͒ 2 O 5 ͑Rϭrare-earth element͒ which displayed only one component with a broad distribution of the hyperfine fields.…”

Low-Temperature Magnetic Properties of LuBaCuFeO5+δ and TmBaCuFeO5+δ

“…The best fit using the Rietveld method is obtained for the acentric tetragonal space group P4 mm, with lattice constants a ¼ 3:774ð1Þ ( A, c ¼ 7:474ð2Þ ( A and a ¼ 3:7812ð2Þ ( A, c ¼ 7:4854ð4Þ ( A, for LuBaCuFeO 5+d and TmBaCuFeO 5+d , respectively (T ¼ 2 K). The lattice parameters of the unit cell of the magnetic structure for these samples are a M ¼ 2a and c M ¼ 2c; with a magnetic propagation vector k ¼ ð The crystal and magnetic structures of the perovskite YBaCuFeO 5+d (YBCFO) have been studied extensively (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) due to the structural similarities with the superconducting cuprate YBa 2 Cu 3 O 7Àd , YBCO. While YBCO presents a square pyramid as the coordination polyhedron around the Cu 2+ ion, YBCFO exhibits two apex-sharing CuO 5 and FeO 5 square pyramids, as can be seen in Fig.…”