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Enhanced higher temperature irreversibility field and critical current density in MgB2 wires with Dy2O3 additions
Superconductor Science and Technology ( IF 3.7 ) Pub Date : 2021-01-13 , DOI: 10.1088/1361-6668/abc73c
Y Yang 1, 2 , M D Sumption 1 , M Rindfleisch 3 , M Tomsic 3 , E W Collings 1
Affiliation  

Bulk samples of magnesium diboride (MgB2) doped with 0.5 wt% of the rare earth oxides (REOs) Nd2O3 and Dy2O3 (named B-ND and B-DY) prepared by standard powder processing, and wires of MgB2 doped with 0.5 wt% Dy2O3 (named W-DY) prepared by a commercial powder-in-tube processing were studied. Investigations included x-ray diffractometry, scanning- and transmission electron microscopy, magnetic measurement of superconducting transition temperature (T c), magnetic and resistive measurements of upper critical field (B c2) and irreversibility field (B irr), as well as magnetic and transport measurements of critical current densities versus applied field (J cm(B) and J c(B), respectively). It was found that although the products of REO doping did not substitute into the MgB2 lattice, REO-based inclusions resided within grains and at grain boundaries. Curves of bulk pinning force density (F p) versus reduced field (b = B/B irr) showed that flux pinning was by predominantly by grain boundaries, not point defects. At all temperatures the F p(b) of W-DY experienced enhancement by inclusion-induced grain boundary refinement but at higher temperatures F p(b) was still further increased by a Dy2O3 additive-induced increase in B irr of about 1 T at all temperatures up to 20 K (and beyond). It is noted that Dy2O3 increases B irr and that it does so, not just at 4 K, but in the higher temperature regime. This important property, shared by a number of REOs and other oxides promises to extend the applications range of MgB2 conductors.



中文翻译:


添加 Dy2O3 增强 MgB2 线材的高温不可逆场和临界电流密度



通过标准粉末加工制备的掺杂有 0.5 wt% 稀土氧化物 (REO) Nd 2 O 3和 Dy 2 O 3 (命名为 B-ND 和 B-DY)的二硼化镁 (MgB 2 ) 的散装样品,以及研究了通过商业粉管工艺制备的掺有0.5wt%Dy 2 O 3的MgB 2 (命名为W-DY)。研究包括 X 射线衍射、扫描和透射电子显微镜、超导转变温度 ( T c ) 的磁测量、上临界场 ( B c2 ) 和不可逆场 ( B irr ) 的磁和电阻测量,以及磁和电阻测量。临界电流密度与施加场的传输测量(分别为J cm ( B ) 和J c ( B ))。结果发现,虽然REO掺杂的产物没有取代到MgB 2晶格中,但REO基夹杂物存在于晶粒内和晶界处。体积钉扎力密度 ( F p ) 与减小场 ( b = B / B irr ) 的曲线表明,磁通钉扎主要是由晶界而非点缺陷造成的。 在所有温度下,W-DY 的F p ( b ) 均因夹杂物引起的晶界细化而得到增强,但在较高温度下, F p ( b ) 仍因 Dy 2 O 3添加剂引起的B irr增加而进一步增加。在高达 20 K(及以上)的所有温度下均为 1 T。值得注意的是,Dy 2 O 3增加了B irr ,并且不仅在 4 K 下如此,而且在更高的温度范围内也是如此。许多 REO 和其他氧化物都具有这一重要特性,有望扩展 MgB 2导体的应用范围。

更新日期:2021-01-13
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