EPR Study of Water Induced Decomposition of the SrCuO2 and Sr2CuO3 Ceramics Surface. The Role of Carbon Dioxide

M.A. Augustyniak-Jabłokowa, Yu.V. Yablokova, I. Jacyna-Onyszkiewiczb, T.A. Ivanovac and V.A. Shustovc aInstitute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland bInstitute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland cKazan Physical Technical Institute RAS, Sibirskii trakt 10/7, 420 029 Kazan, Russia

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Received: 6 07 2007;

Processes of SrCuO_2 and Sr_2CuO_3 ceramics decomposition induced by contact with water and carbon dioxide were studied by EPR. The dominant signals in the spectra were found to originate from Sr_2Cu(OH)_6 (for Sr_2CuO_3) and SrCu(OH)_4·H_2O (for SrCuO_2) compounds. The thermally induced conversion of SrCu(OH)_4·H_2O into Sr_2Cu(OH)_6 was analysed, and its product CuO was found to exist in the nanocrystalline form. The presence of CO_2, reacting with Sr(OH)_2, was shown to modify the decomposition process leading to the appearance of SrCu(OH)_4·H_2O, some hydroxycarbonates and Cu(OH)_2 on the surface of ceramics studied. At temperatures higher than 300ºC CuO reacts back with Sr(OH)_2. For the samples being in contact with atmospheric moisture this compound, deposited on a surface of SrCuO_2, decomposes to Sr_2Cu(OH)_6. The presence of the antiferromagnetic compounds Cu(OH)_2, CuO, and Cu_2[(OH)_2CO_3] in the samples can influence the results of magnetic measurements of the studied ceramics.

DOI: 10.12693/APhysPolA.112.525 PACS numbers: 75.50.Ee, 76.30.Fc, 81.05.Je