The effect of oxygen plasma generated by different microwave modes on NdBa2Cu3O7-δ superconductor: Structure and IR studies

The effect of longitudinal and transverse modes of oxygen plasma generated by microwave source with frequency 2.45 GHz has been used to characterize polycrystalline samples of NdBa2Cu3O6þd (Nd-123) high Tc-superconductor. For this purpose we have developed a simple oxidation technique, used by us earlier, to investigate the effect of different modes on the appearance of superconductivity in Nd-123. Our main results show that the mode of microwave plasma and time of exposure can control the local arrangement of oxygen vacancies in CuOd basal plane. Samples exposed to the transverse mode reveals a well ordered orthorhombic phase transition while the longitudinal modes caused the samples to have a non-superconducting tetragonal structure for all of the exposure time. The Tc vs. d curve does not show the typical 60 K plateau corresponding to the ortho-II phase. The IR spectrum show bands at shorter wavelengths which corresponding to the metal oxides. q 2003 Elsevier Science Ltd. All rights reserved.