Black plate-like single crystals of BaFe3.39(5)Ru 2.61(5)O11 and BaCo1.85(6)Ru4.15(6) O11 were grown from a BaCl2 flux [hexagonal, space group P63/mmc (No. 194), Fe: a = 5.856(1), c = 13.587(1) Å, R1 = 0.029, wR2 = 0.084; Co: a = 5.842(1), c = 13.573(3) Å, R1 = 0.033, wR2 = 0.075]. The crystal structures contain two crystallographic sites with mixed Ru and Fe/Co occupation of different level in octahedral coordination and one site purely occupied by the respective 3d metal. The latter position is in trigonal bipyramidal coordination, with some indication for a displacement of the metal atom towards tetrahedral coordination. According to the charge balance, the ruthenium atoms are incorporated with different electronic situations in the two Ru containing sites. The Co compound may be described as containing Co 2+ and Ru5+ next to Ru3+. Magnetic susceptibility data support this assignment. According to magnetization measurements on oriented crystals, BaCO1.85(6)Ru 4.15(6)O11 is a soft ferromagnetic material with low coercive field and a spontaneous magnetization below Tc = 105 K. It behaves as an electric conductor. However, BaFe3.39(5)Ru 2.61(5)O11 is a narrow band semiconductor material with ferrimagnetic ordering at Tc = 440 K.
|Number of pages||6|
|Journal||Zeitschrift fur Naturforschung - Section B Journal of Chemical Sciences|
|State||Published - Jun 2007|
Bibliographical noteFunding Information:
We thank Dr. Stephan D. Hoffmann for initial introduction and help at the diffractometer software, Ingrid Werner for performing the µ-probe measurements and Vinobalan Du-rairaj for support in electrical resistivity measurements. This work was in part supported by NSF grant DMR-0552267, DoE Grant DOE-FG∅2-97ER45653 and the Elitenetzwerk Bayern within the Advanced Materials Science program.
- Crystal structure
ASJC Scopus subject areas
- Chemistry (all)