High oxygen pressures and the improvement of the Mn+ -- O chemical bond through the stabilization of the highest oxidation states (n+)

An evolution of local structure of Ni and chemical bonding, Ni(III)-O in perovskite lattice with strongly distorted structure is investigated with 57Fe Mössbauer spectroscopy. The Mössbauer spectra for 57Fe-doped TlNiO3 were resolved to two quadrupole doublets with different isomer shifts, which underlines a partial charge disproportionation phenomenon: 2Fe3+ -> Fe3+alpha +Fe3-alpha. This result supports the existence of two different crystallographic sites for Ni in the distorted perovskite lattice