XAS and XPS study of electronic structure of the trivalent cuprate La2Li0.5Cu0.5O4− δ

• Published in: The Journal of physics and chemistry of solids 1993-04, Vol.54 (4), p.499-506
• Main Authors: Merrien, N., Studer, F., Michel, C., Srivastava, P., Sekhar, B.R., Saini, N.L., Garg, K.B., Tourillon, G.
• Format: Article
• Language: English
• Subjects: 3 d9L configuration; Condensed matter: electronic structure, electrical, magnetic, and optical properties; CuL 3-edge; cuprate; Electron density of states and band structure of crystalline solids; Electron states; Exact sciences and technology; La 2Li 0.5Cu 0.5O 4; OK-edge; Physics; XAS; XPS
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/0022-3697(93)90334-N

Well-characterized stoichiometric La 2 Li 0.5 Cu 0.5 O 4− δ ( δ ≈0.04) has been studied using high resolution CuL 3- and OK-edges absorption (XAS) and Cu 2p 3 2 X-ray photoelectron spectroscopy (XPS) techniques. The system is found not to have any Cu 3 d 8 configuration in its ground state but instead reveals a high density of the holes created by doping of monovalent lithium for the divalent copper in the oxygen 2 p levels resulting in a 3 d 9 L copper configuration by charge transfer. The formal valence of copper in it is found to be as high as ≈2.84 in agreement with chemical analysis. The empirical correlation between the shift of the main XPS line (3 d 10 L) and intensity ratio of the satellite (3 d 9) to the main line is examined and, also, a new correlation between the energy spread of the XPS satellite and the energy separation of the CuL 3 absorption lines due to transitions from (3 d 9) and (3d d 9 L) states is suggested.