Microstructure and local structure of spinel LiNixMn 2 - xO4 (x = 0, 0.1 and 0.2) were studied using X-ray diffraction (XRD) and a combination of X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge spectroscopy (XANES) and Raman scattering with the aim of getting a clear picture of the local structure of the materials responsible for the structural stability of LiNixMn 2 - xO4. XRD study showed that Ni substitution caused the changes of the materials' microstructure from the view of the lattice parameter, mean crystallite size, and microstrain. XPS and XANES studies showed the Ni oxidation state in LiNixMn2 - xO4 was larger than + 2, and the Mn oxidation state increased with Ni substitution. The decrease of the intensity of the 1s → 4pz shakedown transition on the XANES spectra indicated that Ni substitution suppressed the tetragonal distortion of the [MnO6] octahedron. The Mn(Ni)-O bond in LiNi xMn2 - xO4, which is stronger than the Mn-O bond in LiMn2O4 was responsible for the blue shift of the A1g Raman mode and could enhance the structural stability of the [Mn(Ni)O6] octahedron.
Bibliographical noteFunding Information:
This work was supported by the Key Project (No. 10411) sponsored by the Ministry of Education of China and the special funds for major state basic research project of China under the Grant 2002CB211802. The work was also partially supported by the Ministry of Information and Communication of Korea [“Support Project of University Information Technology Research Center” supervised by the Korea IT Promotion Agency]. One of the authors, Yingjin Wei, is grateful to Yonsei University and ERC program of MOST/KOSEF (Grant No. R11-2002-102-00000-0) for financial assistance. ITRC supported the XAS work at PAL.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics