Secondary ion mass spectrometry characterization of NdBa₂Cu₃O(7-x) and EuBa₂Cu₃O(7-x) single crystals

The surface features of NdBa₂Cu₃O(7-δ) and EuBa₂Cu₃O(7-δ) single crystals grown from a BaO/CuO flux at high temperatures were investigated by Secondary Ion Mass Spectrometry (SIMS). The crystals obtained have been structurally characterized by X-ray diffraction; the oxygen content has been determined both by structural examination and by iodometric titration, and the electrical resistivity has been measured by the four-thread technique. SIMS has been used to examine the growth features on the (001) faces of the crystals. Impurity inclusions, ionic species from metals with different oxidation state, homo- and hetero-metal clusters, their ionic yields and distribution in different matrices could usefully be compared to information obtained with traditional methodologies utilized in this field. Results obtained by SIMS for both NdBa₂Cu₃O(7-δ) and EuBa₂Cu₃O(7-δ) single crystals could provide new instruments in estimating the property of superconducting materials. For example, the reaction of Al-Cu substitution was observed on the crystal surface, as indicated by mixed cluster signals on the positive and negative ion spectra confirming the already observed interaction between material from crucible and REBa₂Cu₃O(7-δ) (RE = Rare Earths, except for Ce, Pr and Tb).