Abstract
We report Rapid Thermal Quenching (RTQ) studies on MgB2 samples from optimized sintering temperature of 800 °C down to liquid nitrogen temperature with different sintering duration. Superior electron-phonon coupling strength (λe−E2g), critical current density (Jc) and irreversibility fields (Hirr) compared to doped MgB2 were observed without compromising transition temperature Tc. Structural studies showed a contraction of the unit cell due to thermal stress induced by RTQ. Enhanced λe−E2g evaluated from line width, and phonon frequency of Raman spectra using Allen equation was consistent with structural and magnetic studies. Microstructural analysis showed a decrease in grain size resulting in increased Jc and Hirr.
Highlights
The discovery of superconductivity at 39 K on MgB2 by Nagamatsu et al in 2001 led to a plethora of research for improving the superconducting properties of this material.[1]
Hall measurements indicate that holes are responsible for superconductivity in MgB2.5 Mg atoms donate electrons to B atoms, and this results in a shift of the Fermi level, which lies nearer to the flat band resulting in Cooper pair formation
We have investigated rapid thermal quenching (RTQ) studies on bulk MgB2 samples down to LN2 temperature
Summary
The discovery of superconductivity at 39 K on MgB2 by Nagamatsu et al in 2001 led to a plethora of research for improving the superconducting properties of this material.[1]. Is an effective dopant that replaces boron atoms, which are of equal atomic dimensions, and doping studies have been done using carbon in different forms, but only the values of Jc at low temperatures could be improved because of the scattering effects, and T c drops sharply with increasing dopant concentrations.[8,9,10,11] The Jc has a strong correlation with grain size and connected grain boundaries, with various processing methods, Jc can be tuned to desired applications. Rapid thermal quenching down to LN2 temperature induced stress and its effects on T c and grain size in MgB2 is not well understood. We report on a systematic investigation on rapid thermally quenched MgB2 bulk down to LN2 temperature with different duration of sintering and their effects on values of Jc and T c with Raman spectra, X-ray diffraction and microstructural analysis
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