Competition of the nano-inclusions and the effects on critical current density in Ni and SiC co-doped MgB2 bulks. (2016)

• Record Type: Journal Article
• Authors: Cai, Qi; Liu, Yongchang; Guo, Qianying; Ma, Zongqing
• Is Part Of: International journal of nanotechnology. Volume 13:Number 10/11/12(2016)
• Page Start: 832
• Page End: 844
• Publication Date: 2016
• Subjects: MgB2 superconductors -- magnesium diboride -- nano-inclusions -- kinetics -- critical current density -- nanotechnology -- nickel -- Ni -- silicon carbide -- SiC -- phase composition -- microstructure -- superconducting properties; 620.505
• Languages: English
• ISSNs: 1475-7435

Abstract

Samples of (MgB2 )0.96 Ni0.04 + x wt% SiC (with x = 0, 2, 5 and 10) were sintered at 750°C for 30 min, and the phase composition, microstructures, and superconducting properties were investigated. The highest critical current density (Jc ) was obtained in the sample with 2 wt% SiC doping, owing to the precipitation of the nanoscale MgNi2.5 B2 and Mg2 Si on the edge of regular grains. The generation of the two impurities displayed a competition, and consequently the MgNi2.5 B2 is refined to be effective pinning centre, which is in contrast to its influence in the Ni-doped sample. Results from differential thermal analysis and modified Flynn-Wall-Ozawa method also supported our explanation, and the best fitting mechanism function of solid-solid reaction in this system was ascertained. We conclude that 'Avrami-Erofeev, n = 2' is the best fitting mechanism function, indicating random nucleation followed by an instantaneous growth of nuclei. The function of the described mechanism, G(α), is 2[−ln(1 − α)] 1/2, (α is the product fraction), which is different from that of pure MgB2 .