RIS ID
33434
Abstract
We present the following results. (1) We introduce a doping source for MgB2, liquid SiCl4, which is free of C, to significantly enhance the irreversibility field (Hirr), the upper critical field (Hc2), and the critical current density (Jc) with a little reduction in the critical temperature (Tc). (2) Although Si can not be incorporated into the crystal lattice, a significant reduction in the a-axis lattice parameter was found, to the same extent as for carbon doping. (3) Based on the first-principles calculation, it is found that it is reliable to estimate the C concentration just from the reduction in the a-lattice parameter for C-doped MgB2 polycrystalline samples that are prepared at high sintering temperatures, but not for those prepared at low sintering temperatures. Strain effects and magnesium deficiency might be reasons for the a-lattice reduction in non-C or some of the C-added MgB2 samples. (4) The SiCl4-doped MgB2 shows much higher Jc with superior field dependence above 20 K compared to undoped MgB2 and MgB2 doped with various carbon sources. (5) We introduce a parameter, RHH (Hc2 /Hirr), which can clearly reflect the degree of flux-pinning enhancement, providing us with guidance for further enhancing Jc. (6) It was found that spatial variation in the charge-carrier mean free path is responsible for the flux-pinning mechanism in the SiCl4 treated MgB2 with large in-field Jc.
Grant Number
ARC/DP0770205, ARC/LX0882225
Additional Grant Number
http://purl.org/au-research/grants/ARC/DP0770205, http://purl.org/au-research/grants/ARC/LX0882225
Publication Details
Wang, P, Dou, SX, Hossain, M, Cheng, Z, Liao, X, Ghorbani, SR, Yao, Q, Kim, J & Silver, TM (2010), Enhancement of the in-field Jc of MgB2 via SiCl4 doping, Physical Review B, 81(22), pp. 224514-1-224514-6.