J. Phys. IV France 7 (1997) C2-1217-C2-1218
XAS Study on Oxygenated LaSrNiO4 and La2NiO4+δJ.-C. Park1, D.-K. Kim2 and J.-H. Choy3
1 Department of Chemistry, Pusan Women's University, Pusan 617-736, Korea
2 Department of Chemistry, Kyungpook National University, Taegu 702-701, Korea
3 Department of Chemistry, Center for Molecular Catalysis (CMC), Seoul National University, Seoul 151-742, Korea
XANES studies at Ni K-edge have been performed for LaSrNiO3.99, and La2NiO4+δ treated under various atmosphere conditions as well as chemical and electrochemical oxidation methods. XRD patterns of polycrystalline have shown a well crystallized single phase, and valence states of Ni were carefully determined by iodometric titration, resulting in δ=0.01-0.17. The oxidation from Ni(II) to Ni(III) is indicated by an absorption edge shift to higher energy side, which is in good agreement with the amount of excess oxygen determined by iodometric titration. XANES study suggests that the doped holes in nickelates are more localized on nickel sites than those in cuprate.
© EDP Sciences 1997