Reducing delamination in MgB2 films deposited on Hastelloy tapes by applying SiC buffer layers

Vapor annealing synthesis of non-epitaxial MgB2films on glassy carbon

“…Based on particle analysis, 160 nm (figure 6(d)) and 650 nm (figure 6(b)) films have average crystallite widths of 11 and 10 nm, respectively. This indicates the presence of multiple nucleation sites and crystal growth proceeding from the B/Mg (solid/vapor) interface, and is in agreement with numerous previous reports of highly textured surfaces of non-epitaxial MgB 2 films [9,18,22,32]. In thinner films (25 and 55 nm) such multiple crystallite formation is not observed, leading to a smooth surface with a root-mean-square (rms) roughness of 1.1 nm (for areas without alloy nanoparticles), as opposed to a rms roughness of 37.9 nm for 160 nm thick films decorated by elongated crystallites.…”

“…Molecular beam epitaxy [15,16], reactive evaporation [17], and hybrid physical-chemical vapor deposition (HPCVD) [6,7,14] have been particularly successful in making high-quality epitaxial films. In contrast, the growth of non-epitaxial MgB 2 films on amorphous or polycrystalline substrates has attracted relatively limited attention and yielded less promising results [9,[17][18][19][20][21][22]. Indeed, non-epitaxial films typically exhibit large surface roughness and reduced T c [9,[17][18][19][20][21][22].…”

“…In contrast, the growth of non-epitaxial MgB 2 films on amorphous or polycrystalline substrates has attracted relatively limited attention and yielded less promising results [9,[17][18][19][20][21][22]. Indeed, non-epitaxial films typically exhibit large surface roughness and reduced T c [9,[17][18][19][20][21][22]. For example, films prepared on glassy carbon substrates by co-deposition of Mg and B followed by annealing at 700 °C had large roughness, depressed T c values of 25-30 K, and compositional non-uniformity manifested as the Mg/B ratio varying as a function of depth [19,20].…”

Enhancement in High-Field Jc Properties and the Flux Pinning Mechanism of ZnO-Buffered MgB2 Films

“…Several studies have been conducted to enhance the pinning properties of MgB 2 at high magnetic fields by chemical doping, − grain size reduction, − and particle irradiation. − For the thin-film form of MgB 2 , various kinds of buffer layers have been tried. − The use of ZnO as a buffer layer on metallic substrates has yielded promising results. ZnO buffer layers with thicknesses ranging from tens to hundreds of nanometers do not significantly degrade the T c values while suppressing delamination and hindering unwanted reactions between MgB 2 and the metal substrates. , As the ZnO buffer layer thickens, the local structure is distorted owing to the atomic bond length variation between Mg–B and Mg–Mg, which leads to the T c fluctuation.…”

Superconducting films of MgB2 via ion beam mixing of Mg/B multilayers

“…The growth of MgB 2 films on such non-planar substrates is inherently non-epitaxial and has proven to be challenging. Non-epitaxial films typically exhibit high surface roughness and a diminished critical superconducting transition temperature (T c ) [1,4,[6][7][8] when compared to epitaxially grown high-quality MgB 2 thin films [3,9].…”