Effect of Cu doping in MgB2 superconductor at various processing temperatures

The effects of Cu doping in MgB2 superconductor has been studied at different processing temperatures. The polycrystalline samples of Mg1-xCuxB2 with x = 0.05 were synthesized through the in-situ solid sate reaction method in argon atmosphere at different temperature range between 800-900 degrees C. The samples were characterized through X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and low temperature R-T measurement techniques for the phase verification, microstructure and superconducting transition temperature, respectively. The XRD patterns of Mg1-xCuxB2 (x = 0.05) do not exhibit any impurity traces of MgB4 or MgB6 and they show the sharp transition in the samples prepared at 850 degrees C. The onset transition temperature of the prepared samples is around 39 K, which is almost the same as that for the pure MgB2. This indicates that Cu doping in MgB2 does not affect the transition temperature. The SEM micrograph of Mg0.95Cu0.05B2 has shown that the sample is dense with grain size smaller than 1 mu m. (c) 2006 Elsevier B.V. All rights reserved.