Oxygen Stoichiometry in Co-1212, Co-1222 and Co-1232 of Homologous Series Co-12s2 of Category-B Layered Copper Oxides

Y. Morita; V. P. S. Awana; H. Yamauchi; M. Karppinen

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Oxygen Stoichiometry in Co-1212, Co-1222 and Co-1232 of Homologous Series Co-12s2 of Category-B Layered Copper Oxides

Y. Morita·V. P. S. Awana·H. Yamauchi·M. Karppinen

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Abstract

Here results of a systematic study on oxygen stoichiometry are reported for the first three members of the novel CoSr2(Y,Ce)sCu2O5+2s or Co-12s2 homologous series, i.e. Co-1212, Co-1222 and Co-1232 phases with a SrO-CoO1-SrO-CuO2-(Y,Ce)-[O2-(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 an-nealings carried out in a thermobalance. It was revealed that all the three phases are rather stoichiometric in oxygen content and stable against both oxygenative and reductive an-nealings. The present results for the Co-12s2 homologous series suggest that not only the CoO1 charge reservoir but also the nominally oxygen-stoichiometric B-[O2-B]s-1 fluo-rite block, that is the characteristic structural element for the Co-12s2 (s > 1) phases and all other layered copper oxides of category-B [H. Yamauchi and M. Karppinen, Superlatt. Microstructr. 21A (1997) 128] is non-tunable in terms of the oxygen content.

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Y. Morita, V. P. S. Awana, H. Yamauchi, M. Karppinen. 2002-10-30. Oxygen Stoichiometry in Co-1212, Co-1222 and Co-1232 of Homologous Series Co-12s2 of Category-B Layered Copper Oxides. https://arxiv.org/abs/cond-mat/0210660

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