The average valence, ValO, of the oxygen anions in the perovskite oxide BaTiO3, was found using O1s photoelectron spectra to be −1.55. This experimental result is close to the theoretical value for BaTiO3 (−1.63) calculated by Cohen [Nature 358, 136 (1992)] using density functional theory. Using the same approach, we obtained values of ValO for several monoxides, and investigated the dependence of ValO and the ionicity on the second ionization energy, V(M2+), of the metal cation. We found that the dependence of the ionicity on V(M2+) in this work is close to that reported by Phillips [Rev. Mod. Phys. 42, 317 (1970)]. We therefore suggest that O1s photoelectron spectrum measurements should be accepted as a general experimental method for estimating the ionicity and average valence of oxygen anions.

The oxygen vacancy model has been used to explain the magnetic and electrical transport properties of dilute magnetic semiconductors and resistive switching. In particular, some authors have claimed that they found a symmetric peak corresponding to the oxygen vacancies in O1s photoelectron spectra. In this paper, using X-ray photoelectron spectra with argon ion etching, it is shown that this symmetric peak may also be interpreted as being related to O1− anions, rather than to oxygen vacancies.

Powder samples of the ABO3 perovskite manganites Pr0.6Sr0.4CrxMn1-xO3 (0.00≤x≤0.30) were synthesized using the sol-gel method. X-ray diffraction analyses showed that all the samples had a single-phase orthorhombic structure. By analyzing magnetic parameters on the basis of the O2p itinerant electron model, we found that there are two magnetic transition temperatures, TCM and TCP, corresponding to changes in the magnetic ordering for the Mn and Pr cations, respectively. The magnetic moments of Mn3+ and Cr3+ cations within the B sublattice show canted ferromagnetic coupling, and the magnetic moments of the Pr cations within the A sublattice also show canted ferromagnetic coupling. However, the total magnetic moment of the A sublattice shows antiferromagnetic coupling against that of the B sublattice. The assumption of the canted ferromagnetic coupling within the B sublattice was confirmed using magnetoresistance experimental results.