Structural, magnetic, and Co K-edge X-ray absorption near-edge structure (XANES) spectroscopic studies for the stoichiometric La1-xEu xCoO3 (0 ≤ x ≤ 1) system with trivalent Co 3+ are reported. The thermally-excited spin-state transition from low-spin (LS) to intermediate-spin (IS) state increases from Ts ∼ 105 K for LaCoO3 (x = 0) to ∼140 K for x = 0.25, to ∼200 K for x = 0.5, and extrapolates to ∼295 K for EuCoO3 (x = 1), where the IS state is a mixture of d6 (t2g 5 eg1) and d7L (t2g 5 eg2 with a ligand hole) with filled t 2g majority spin states. The small pre-edge feature observed in room temperature XANES for the system in the IS state is from the 1s-3d quadrupole transition, which is weakly allowed through the hybridization of Co 4p states with 3d states of the neighboring Co atoms. For LaCoO3, the pre-edge can be fitted using three Gaussian peaks with energy separations ΔE(P 2-P1) = 2.0 eV and ΔE(P3-P2) = 1.5 eV, where P1, P2, and P3 presumably correspond to the unfilled t2g minority, eg majority, and eg minority spin states, respectively.
|Number of pages||9|
|Journal||Chinese Journal of Physics|
|Publication status||Published - 2003 Dec 1|
ASJC Scopus subject areas
- Physics and Astronomy(all)