EPR Study of Water Induced Decomposition of the SrCuO2and Sr2CuO3Ceramics Surface. The Role of Carbon Dioxide

Processes of SrCuO2 and Sr2CuO3 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 Sr2Cu(OH)6 (for Sr 2 CuO 3 ) and SrCu(OH) 4 •H 2 O (for SrCuO 2 ) compounds.The thermally induced conversion of SrCu(OH)4•H2O into Sr2Cu(OH)6 was analysed, and its product CuO was found to exist in the nanocrystalline form.The presence of CO2, reacting with Sr(OH)2, was shown to modify the decomposition process leading to the appearance of SrCu(OH) 4 •H 2 O, some hydroxycarbonates and Cu(OH)2 on the surface of ceramics studied.At temperatures higher than 300 • C CuO reacts back with Sr(OH) 2 .For the samples being in contact with atmospheric moisture this compound, deposited on a surface of SrCuO2, decomposes to Sr2Cu(OH)6.The presence of the antiferromagnetic compounds Cu(OH) 2 , CuO, and Cu 2 [(OH) 2 CO 3 ] in the samples can influence the results of magnetic measurements of the studied ceramics.