Lithium-based transition-metal oxides for battery electrodes analyzed by x-ray photoelectron spectroscopy. X. Li₄Ti₅O₁₂

X-ray photoelectron spectroscopy (XPS) and x-ray-induced Auger electron spectroscopy were used to analyze untreated Li₄Ti₅O₁₂ powders obtained from Ishihara Sangyo Kaisha, Ltd. and Samsung Fine Chemicals Company, Ltd. X-ray photoelectron and x-ray-induced Auger electron spectra were obtained using incident monochromatic Al K_α radiation at 0.834 01 nm. A survey spectrum together with O 1s, Ti 2p, C 1s, Ti 3s, Li 1s, and Ti 3p are presented. The spectra indicate the principal core level photoelectron and Auger electron signals and show only minor potassium signal. Making use of the O 1s, Li 1s, and Ti 3p lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed powder surfaces from Ishihara Sangyo Kaisha, Ltd. and Samsung Fine Chemicals Company, Ltd. of Li₄Ti_4.7O_14.1 and Li₄Ti_4.3O_13.2, respectively.