Abstract
It is proposed that the anomalously high T c ( T c > 200 K) observed in some cuprates can be explained by formation of surface epitaxial Cu 2O 2 layers with the NaCl structure and with double the concentration of Cu ions as compared with the inner CuO 2 layers of superconducting cuprates. The optimal mixed oxidation state of copper ions in the layers can be obtained by deviations from stoichiometry (Cu 2- δ O 2) or by an electron exchange with cuprate substrates. A similar situation is possible on the surface of La 2NiO 4, where epitaxial layers of Ni 2O 2- δ can be formed during annealing in reducing atmosphere. These layers contain Ni ions in the low-spin configuration and mixed oxidation state Ni 1+−Ni 2+. In this case the Ni ions are isoelectronic to the Cu ions in the mixed oxidation state Cu 2+−Cu 3+.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
