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Phase formation and superconductivity of fe-tube encapsulated and vacuum-annealed MgB2

Show simple item record Singh, K. P. Awana, V. P. S. Shahabuddin, M. D. Husain, M. Saxena, R. B. Nigam, Rashmi Ansari, M. A. Gupta, Anurag Narayan, Himanshu Halder, S. K. Kishan, H. 2016-12-07T12:30:46Z 2016-12-07T12:30:46Z 2006
dc.identifier.issn 0217-9849 (print)
dc.identifier.issn 1793-6640 (online)
dc.description.abstract We report optimization of the synthesis parameters viz. heating temperature (TH), and hold time (thold) for vacuum-annealed (10􀀀5 Torr) and LN2 (liquid nitrogen) quenched MgB2 compound. These are single-phase compounds crystallizing in the hexagonal struc- ture (space group P6=mmm) at room temperature. Our XRD results indicated that for phase-pure MgB2, the TH for 10􀀀5 Torr annealed and LN2-quenched samples is 750 C. The right stoichiometry i.e., MgB2 of the compound corresponding to 10􀀀5 Torr and TH of 750 C is found for the hold time (thold) of 2.30 hours. With varying thold from 1{4 hours at xed TH (750 C) and vacuum (10􀀀5 Torr), the c-lattice parameter decreases rst and later increases with thold (hours) before a near saturation, while the a-lattice parameter rst increases and later decreases beyond a thold of 2.30 hours. The c=a ratio versus thold plot showed an inverted bell-shaped curve, touching the lowest value of 1.141, which is the reported value for perfect stoichiometry of MgB2. The optimized stoichi- metric MgB2 compound exhibited superconductivity at 39.2 K with a transition width of 0.6 K. In conclusion, the synthesis parameters for phase pure stoichimetric vacuum- annealed MgB2 compound are optimized and are compared with widely-reported Ta tube encapsulated samples. en_ZA
dc.language.iso en en_ZA
dc.publisher World Scienti fic Publishing Company en_ZA
dc.rights Copyright World Scienti fic Publishing Company en_ZA
dc.source Modern Physics Letters B, Vol. 20, No. 27 (2006) 1763{1769 en_ZA
dc.subject MgB2 en_ZA
dc.subject Fe-encapsulations en_ZA
dc.subject superconductivity en_ZA
dc.subject vacuum synthesis en_ZA
dc.title Phase formation and superconductivity of fe-tube encapsulated and vacuum-annealed MgB2 en_ZA
dc.type Article en_ZA

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