Second-phase segregation and micro strain/lattice parameter dependent transition temperature in polycrystalline MgB2. (8th September 2016)

• Record Type: Journal Article
• Authors: Cai, Qi; Liu, Yongchang; Guo, Qianying; Ma, Zongqing; Li, Huijun
• Is Part Of: Superconductor science & technology. Volume 29:Number 10(2016:Oct.)
• Publication Date: 2016-09-08
• Subjects: MgB2 superconductors -- quenching -- second-phase segregation -- micro strain -- superconducting properties; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/0953-2048/29/10/105013
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: Un-doped, metal-doped, and carbon-doped MgB2 samples were prepared by furnace cooling and quenching to investigate the second phase behavior and the resultant critical current density J c performance under different heat treatment processes, which is infrequently mentioned, and to explore the strain/lattice parameter dependence of the superconducting transition temperature. To release the residual stress, quenching induced second-phase segregation in these MgB2 samples shows a negative effect on the J c . Nevertheless, the dislocations and the lattice distortion assisted the enhancement of the high-field J c in the un-doped and metal-doped MgB2 samples, which indicated that quenching could be technically applied for the fabrication of metal-sheathed MgB2 wires and tapes to obtain excellent J c . After evaluating the micro strain and the lattice parameters' ( c and a for hexagonal lattice) variation, a dome was observed in the illustration of the strain/lattice parameter c / a dependence of T c, which differed from the reported linear relation in previous work. This suggests that the c / a ratio and the strain may be the predominant parameters for scaling of the superconducting dome width in the superconducting phase diagram of MgB2 .