Large critical current densities and pinning forces in CSD-grown superconducting GdBa₂Cu₃O_7−x-BaHfO₃nanocomposite films

Abstract

GdBa 2 Cu 3 O 7 x -BaHfO 3 (GdBCO-BHO) nanocomposite (NC) films containing 12 mol% BHO nanoparticles were prepared by chemical solution deposition (CSD) following the TFA route on SrTiO 3 (STO) single crystals and buffered metallic tapes supplied by two different companies: Deutsche Nanoschicht GmbH and SuperOx. We optimized the preparation of our GdBCO-BHO solutions with acetylacetone making the film synthesis very robust and reproducible, and obtained 220 nm films with excellent superconducting properties. We show the structural, morphological and superconducting properties of the films after a careful optimization of the processing parameters (growth temperature, oxygen partial pressure and heating ramp). The films reach critical temperatures (T c ) of ∼94 K, self-field critical current densities (J c ) of >7 MA cm 2 and maximum pinning force densities (F p ) of ∼16 GN m 3 at 77 K on STO and T c of ∼94.5 K and J c > 1.5 MA cm 2 on buffered metallic tapes. The transport properties under applied magnetic fields are significantly improved with respect to the pristine GdBCO films. The GdBCO-BHO NC films on STO present epitaxial c-axis orientation with excellent out-of-plane and in-plane texture. The films are, in general, very dense with a low amount of pores and only superficial indentations. On the other hand, we present, for the first time, a systematic study of CSD-grown GdBCO-BHO NC films on buffered metallic tapes. We have used the optimized growth conditions for STO as a reference and identified some limitations on the film synthesis that should be overcome for further improvement of the films' superconducting properties.

Rapid Pyrolysis of SmBa2Cu3O7-δ Films in CSD-MOD Using Extremely-Low-Fluorine Solutions

“…For the preparation of the full-TFA solution (SmBCO-TFA) we used the procedure described in our previous works [17,27]. In summary, this is a 1.5 molar solution (over all cations) with a 1:2:3 ratio of Sm, Ba, and Cu dissolved in dry methanol.…”

“…For the SmBCO-TFA films we used the "standard pyrolysis process" described by Erbe et al [17]. Subsequently, the SmBCO-ELF films were crystallized using a similar growth process to the one described by Cayado et al [27]. In this particular case, the films were heated for 90 min in a humid O 2 /N 2 gas at several T crys (780-840 • C) and pO 2 (20-100 ppm).…”

“…However, only little work has been spent to grow REBCO films with other rare earth elements with ELF solutions.As pointed out by Wu et al [20] and Li et al [22], the reaction mechanism for the formation of REBCO films using ELF solutions is still a "BaF 2 " process, which is a well-understood process. There are also multiple studies on the influence of the RE 3+ ionic radius on the superconducting properties of REBCO compounds, e.g., [23][24][25][26][27], and some of these compounds have been shown to exhibit larger T c and J c values than YBCO [28][29][30]. However, the synthesis of some of these compounds is much more complicated than for YBCO and requires more effort for both optimization and understanding.…”

Chemical solution deposition of Y1−xGdxBa2Cu3O7−δ–BaHfO3 nanocomposite films: combined influence of nanoparticles and rare-earth mixing on growth conditions and transport properties

“…The preparation method for the nanocomposite TFA solution is as described in ref. 9. First, two different solutions are prepared:…”

“…However, other REBCO compounds have attracted the attention of the community because they could exhibit better properties than YBCO. [5][6][7][8][9] These improvements in the properties are caused by variations in the electronic structures, valence states and the ionic radii of the rare earth (RE) atoms within the structures. [10][11][12][13] Although some of these REBCO compounds show better transport properties than YBCO, their synthesis may be much more complicated.…”