Mechanism of enhanced critical fields and critical current densities of MgB2 wires with C/Dy$$^{2}$$O3 co-additions

Journal Article · Wed Jan 11 00:00:00 EST 2023 · J.Appl.Phys.

DOI:https://doi.org/10.1063/5.0130589· OSTI ID:1989914

Wan, F. ^[1]; Sumption, M. D. ^[2]; Collings, E. W. ^[2]

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1. Ohio State U.; Fermilab
2. Ohio State U.

A series of monofilamentary powder-in-tube MgB2 wires were fabricated with 2 mol. % C doping and co-additions of 0–3 wt. % Dy2O3. Irreversibility fields (μ0Hirr), upper critical fields (μ0Hc2), and transport critical currents were measured, and from these quantities, anisotropies (γ) and electronic diffusivities (Dπ,σ) were estimated. The addition of 1 wt. % Dy2O3 to already optimally C-doped MgB2 wires produced higher Hc2//ab, Hc2//c, and Hirr values at 4.2 K. In addition, the critical current density, Jc, increased with Dy2O3 concentration up to 1 wt. % where non-barrier Jc reached 4.35 × 104 A/cm2 at 4.2 K, 10 T. At higher temperatures, for example, 20 K and 5 T, co-additions of 2 mol. % C and 2 wt. % Dy2O3 improved non-barrier Jc by 40% and 93% compared to 2 and 3 mol. % C doping, respectively. On the other hand, measurements of Tc showed that C/Dy2O3 co-additions increase interband scattering rates at a lower rate than C doping does (assuming C doping levels giving similar levels of low-T μ0Hc2 increase as co-addition). Comparisons to a two-band model for μ0Hc2 in MgB2 allowed us to conclude that the increases in Hc2//ab, Hc2//c, and Hirr (as well as concomitant increases in high-field Jc) with Dy2O3 addition are consistent with increases primarily in intraband scattering. This suggests C/Dy2O3 co-addition to be a more promising candidate for improving non-barrier Jc of MgB2 at temperatures above 20 K.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Ohio State U.
• Sponsoring Organization: US Department of Energy
• Grant/Contract Number: AC02-07CH11359
• OSTI ID: 1989914
• Report Number(s): FERMILAB-PUB-23-152-TD; oai:inspirehep.net:2650766
• Journal Information: J.Appl.Phys., Journal Name: J.Appl.Phys. Journal Issue: 2 Vol. 133
• Country of Publication: United States
• Language: English

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36 MATERIALS SCIENCE