Surface composition of CoxNi1−xO solid solutions by X-ray photoelectron and Auger spectroscopies

Surface properties of LiCoO2, LiNiO2 and LiNi1−xCoxO2

“…The sensitivity factor includes XPS or AES cross sections, electron escape depth and a spectrometer transmission function for data taken under the specifi c spectral conditions. These values have been reported elsewhere for nickel and cobalt oxide standard compounds [62] and [63].…”

“…verse spinel distribution. For these materials, the O 1s is comparable with that of NiO [62] and [63]. Ni 3+ has been reported as a "defect structure" in NiO and oxidized nickel metal substrates [64], [65], [66], [67] and [68]; however the O 1s binding energy associated with this species is generally reported at values well in excess of 530 eV.…”

Nature of oxygen at rocksalt and spinel oxide surfaces

“…NiCo 2 O 4 13,14 powders were prepared by sol-gel methods and MnCo 2 O 4 were prepared by thermal decomposition from nitrates. 15,16 The homogeneity and bulk stoichiometry of the two samples were determined with powder x-ray diffraction using a Rigaku Geigerflex diffractometer equipped with a Cu K␣ anode.…”

“…Inverse spinels, e.g., Fe 3 O 4 and NiCo 2 O 4 , form a related structure; the 2ϩ cations now occupy octahedral sites with the 3ϩ cations divided equally between the remaining filled octahedral sites and tetrahedral sites of the lattice. Because of the similarity in lattice structure, spinels and rocksalt oxides often interconvert at TMO surfaces, [1][2][3][4] depending upon the oxidizing/reducing nature of their environment. Substitutional and interstitial defects are also common in these materials 5 and surface compositions can differ from that of the bulk due to either thermodynamic or kinetic factors.…”

“…Substitutional and interstitial defects are also common in these materials 5 and surface compositions can differ from that of the bulk due to either thermodynamic or kinetic factors. 4,6 Water is one oxidant commonly encountered under ambient conditions, and most air-exposed TMOs are covered with one or more hydroxylated layers. 7 While hydroxylation occurs rapidly under ultrahigh vacuum ͑UHV͒ only at isolated defect sites, 8,9 air-exposed TMO substrates can form relatively thick hydroxylated layers that persist in UHV to temperatures of 973 K or higher for substantial periods of time.…”