Oxygen stoichiometry in Co-1212, Co-1222 and Co-1232 of the homologous series Co-12s2 of "category-B" layered copper oxides

M. Karppinen*, V. P.S. Awana, Y. Morita, H. Yamauchi

*Corresponding author for this work

Research output: Contribution to journalConference articleScientificpeer-review

13 Citations (Scopus)


The results of a systematic study on oxygen stoichiometry are reported for the first three members of the novel CoSr2(Y,Ce)sCu 2O5+2s±δ or Co-12s2 homologous series, i.e. Co-1212, Co-1222 and Co-1232 phases, with a SrO-CoO 1±δ-SrO-CuO2-(Y,Ce)-[O 2-(Y,Ce)]s-1-CuO2 layered structure. The oxygen content was precisely determined by two independent chemical techniques: coulometric Cu+/Cu2+ titration and iodometric titration. Furthermore, oxygen stability/tunability was investigated by means of oxygenative and reductive annealings carried out in a thermobalance. It was revealed that all the three phases are rather stoichiometric in oxygen content (δ ≈ 0) and stable against both oxygenative and reductive annealings. The present results provide us with an indication that the nominally oxygen-stoichiometric B-[O2-B]s-1 "fluorite block", the characteristic structural element for all layered copper oxides of "category-B" [H. Yamauchi, M. Karppinen, Superlatt. Microstructr. 21A (1997) 128], is non-tunable in terms of the oxygen content not only in the Co-12s2 (s > 1) phases but also in other category-B phases.

Original languageEnglish
Pages (from-to)82-86
Number of pages5
Issue numberPART 1
Publication statusPublished - Oct 2003
MoE publication typeA4 Article in a conference publication
EventInternational Symposium on Superconductivity - Yokohama, Japan
Duration: 11 Nov 200213 Nov 2002
Conference number: 15


  • "Category-B" homologous series
  • Co-based layered copper oxides
  • Fluorite block
  • Oxygen stoichiometry


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