The effects of sintering temperature on superconductivity in MgB₂/Fe wires

Abstract

We studied the effects of sintering temperature on the phase transformation, lattice parameters, full width at half-maximum (FWHM), strain, critical temperature (Tc), critical current density (Jc) and resistivity (ρ) in MgB2/Fe wires. All samples were fabricated by the in situ powder-in-tube method (PIT) and sintered within a temperature range of 650–900 °C. It was observed that wires sintered at low temperature, 650 °C, resulted in higher Jc up to 12 T and lower Tc. The best transport Jc value reached 4200 A cm−2 at 4.2 K and 10 T. This is related to the grain boundary pinning due to small grain size. On the other hand, wires sintered at 900 °C had a lower Jc in combination with a higher Tc.

Raman study on the effects of sintering temperature on the Jc(H) performance of MgB2 superconductor

“…17,18 To confirm the physical mechanism of the J c ͑H͒ variation and the origin of the flux pinning force, F p =−J c H, with different sintering temperatures, Raman scattering measurements were employed in this study. Raman scattering has the benefits of excellent energy resolution, a relatively large penetration depth, the ability to selectively measure different portions of the Fermi surface͑s͒, 19 and, especially in superconductors, the benefit of revealing both the existence of the superconducting gap and its strong coupling to some of the active Raman phonons.…”

Effects of heat treatment temperature on the formation of MgB2 bulk superconductors prepared using MgB4 and Mg powder

“…There are two different methods that can be used to fabricate MgB 2 : an ex-situ process [5][6][7][8] and an in-situ [9][10][11][12]. In the ex-situ process MgB 2 powder was used as a precursor [5][6][7][8].…”

“…This is because of the weakly-linked grain boundaries of MgB 2 [5]. On the other hand, with the in-situ process, a mixture of Mg and B powders were used as raw materials [9][10][11][12]. The in situ processed MgB 2 showed a J c higher than that of the ex-situ processed MgB 2 .…”

Effects of the size of Mg powder on the formation of MgB2and the superconducting properties

“…MgB 2 superconductors can be fabricated either by an ex-situ process or an in-situ process [5][6][7][8][9][10][11][12]. In the ex-situ process, readily synthesized MgB 2 powder is used as a raw material [5][6][7][8], whereas in the in-situ process a powder mixture of Mg and B is used [9][10][11][12].…”

“…In the ex-situ process, readily synthesized MgB 2 powder is used as a raw material [5][6][7][8], whereas in the in-situ process a powder mixture of Mg and B is used [9][10][11][12]. The ex-situ processed MgB 2 superconductors showed a higher density with a small number of pores and excellent mechanical properties [6][7].…”