SECONDARY-ION MASS-SPECTROMETRY CHARACTERIZATION OF NDBA2CU3O7-X AND EUBA2CU3O7-X SINGLE-CRYSTALS

The surface features of NdBa2Cu3O7-delta and EuBa2Cu3O7-delta single c rystals grown from a BaO/CuO flux at high temperatures were investigat ed by Secondary Ion Mass Spectrometry (SIMS). The crystals obtained ha ve been structurally characterized by X-ray diffraction; the oxygen co ntent has been determined both by structural examination and by iodome tric titration, and the electrical resistivity has been measured by th e four-thread technique. SIMS has been used to examine the growth feat ures on the (001) faces of the crystals. Impurity inclusions, ionic sp ecies from metals with different oxidation state, homo- and hetero-met al clusters, their ionic yields and distribution in different matrices could usefully be compared to information obtained with traditional m ethodologies utilized in this field. Results obtained by SIMS for both NdBa2Cu3O7-beta and EuBa2Cu3O7-delta single crystals could provide ne w instruments in estimating the property of superconducting materials. For example, the reaction of Al-Cu substitution was observed on the c rystal surface, as indicated by mixed cluster signals on the positive and negative ion spectra confirming the already observed interaction b etween material from crucible and REBa2Cu3O7-delta (RE = Rare Earths, except for Ce, Pr and Tb). (C) 1998 John Wiley & Sons, Ltd.