A member of the R3MO7 family containing two magnetic cations, Gd3RuO7, has been synthesized by high-temperature solid-state reaction. The structure has been determined by single-crystal methods: space group Cmcm(#63), a0=10.643(2) Å, b0=7.345(1) Å, c0=7.380(1) Å, V=576.90(14) Å3, Z=4, R1=0.021, wR2=0.047. The most important structural feature is the one-dimensional RuO6 chain running parallel to the c axis. In a wide temperature range the conductivity of Gd3RuO7 follows the dependence ln(ρ)∝Τ1/2, which is typical for Mott variable-range hopping of localized carriers in one dimension. The magnetic susceptibility obeys the Curie-Weiss law with θp=-7.5 K and Curie constant Cmol=25 emu K/mole. Magnetization data reveal two successive transitions at about 14.5 and 8 K, which indicates independent ordering of Ru and Gd moments, respectively. The analysis shows that in total 27 (8Ag+8B1g+5B2g+6B3g) Raman-active modes are expected for Gd3RuO7. As a larger number of Ag lines (10) are observed in the polarized Raman spectra, we suggest that two of the Ag lines (at 233 and 780 cm-1) either arise from local vibrations or are of nonphonon origin.
|Journal||Physical Review B-Condensed Matter|
|Publication status||Published - 1 Nov 2000|