ABSTRACTELECTROLESS DEPOSITION OF SUPERCONDUCTING MAGNESIUM DIBORIDE THIN FILMS ON VARIOUS SUBSTRATESbyKHRUPA SAAGAR VIJAYARAGAVANMAY 2010Advisor: Dr. Susil K PutatundaDr. Gavin LawesMajor: Chemical EngineeringDegree: Masters of ScienceSuperconducting thin films of magnesium diboride were synthesized by a novel electroless plating process. Electroless plating shares many similarities to electroplating with the major difference being the absence of a continuous bias voltage. Significantly, this work represents the first investigation where electroless deposition has been used to prepare compounds, as opposed to the elemental metals considered in all previous studies. Magnesium Diboride is a recently discovered superconducting material with a relatively high transition temperature (Tc = 39 K). MgB2 plated wires offer potential applications for MRI (magnetic imaging resonance), NMR (nuclear magnetic resonance), particle accelerators and the electronic industry. The low cost and wide availability of magnesium diboride make this material a possible future source of superconducting magnets to replace the Nb-Sn (Niobium Tin) alloy that that is presently used. The MgB2 thin films were synthesized on conducting substrates including silver, gold, copper and insulating silicon. Thin solid film deposition is widely used in the electronic industry for benefits in high power storage, transmission and low power consumption. In this electroless plating of MgB2, sodium hypophosphite was used as a reducing agent in acidic and alkaline plating solutions. The structural, morphological and superconducting properties of these films were examined using X-ray diffraction, temperature-dependent magnetometry, scanning electron microscopy (SEM), energy-dispersive X-ray analysis (SEM-EDX) and Raman spectroscopy. The magnetic study of these thin films indicates the presence of clear superconducting phase below the critical temperature of roughly 39K with a diamagnetic susceptibility corresponding to approximately 1-2% of a perfect superconductor for different substrates. The vibrational spectroscopy of these thin films confirms the crystalline nature and correct stoichiometry of MgB2. The structural and microstructural analysis of these thin films indicates the polycrystalline nature of the film with presence of small amount of impurity phases of different magnesium and boron compounds. The SEM analysis also determines the cross sectional thickness acquired on substrate surface. The synthesis process of these films and their superconducting properties will be discussed in detailed.
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