An industrial R&D programme is ongoing at SuperOx, aimed at improving 2G HTS wire performance in magnetic field. We introduce perovskite artificial pinning centres (APC) into the HTS layer matrix. In contrast to most studies described in the literature, we use the high rate production processing parameters and PLD equipment at SuperOx. This paper reports the results of Phase I of this programme. We fabricated 2G HTS wires by pulsed laser deposition of GdBCO films doped with 6%, 12% and 18% (molar) of BaSnO ₃ and 6% (molar) of BaZrO ₃ , and compared their performance with an undoped reference sample. The depositions were carried out at production growth rates of 375, 560 and 750 nm min ⁻¹ by varying laser pulse frequency. BaZrO ₃ and BaSnO ₃ formed columnar semi-coherent nanoinclusions in the GdBCO film matrix. The average transverse size of the nanocolumns was about 5 nm, and their volume density correlated with the dopant concentration. All doped samples exhibited much lower angular anisotropy of in-field critical current and higher lift-factors than the undoped sample. Samples containing 6% BaSnO ₃ and deposited at the lower growth rates, had higher I _c than the undoped sample in the entire temperature range, in a wide range of magnetic field ( B // c ). The sample containing 6% BaZrO ₃ had higher I _c than the undoped sample at 20 and 4.2 K. These results are an encouraging start of our programme, as they show a positive impact of APC introduced into 2G HTS wires fabricated at production throughput. Phase II work will be focussed on maximising the improvements in specific temperature and field conditions, as well as on the verification of reproducibility of the improvements in production wires.

The morphology and structure of damaged regions (tracks) produced by swift heavy 167, 77, and 46 MeV ¹³²Xe²³⁺ ions in YBCO-based second generation industrial high temperature superconductors wires (2G HTS) were studied using transmission electron microscopy. It was shown that ions produce tracks aligned along the ion trajectory but of morphology depending on their energy: continuous, nearly continuous, or discontinuous tracks like prolate ellipsoids of 10–15 nm in length and spheroids of 5 nm in diameter. The damaged regions of about 5 nm in diameter contain an amorphous material with a lower density compared to the pristine YBCO. The material density drops from 6300 kg m⁻³ for YBCO matrix to 3600 kg m⁻³ inside the tracks. Barium enrichment was found in the vicinity of the track at a distance of about 10 nm from the center of the defect. Ion damage tracks with different morphologies showed different effectivenesses as pinning centers. Tracks composed of discontinuous pinning centers—spheroids of about 5 nm in diameter—bring the best enhancement of the critical current density. It occurs for the lowest ion energy (46 MeV) in the range of energy loss of 8.9 keV/nm–4.7 keV/nm for Xe ions. The samples showed highest critical current densities of 56 MA/cm² (4.2 K) and 3 MA/cm² (77 K) in self-field, while in magnetic fields of 8 T, the values of 17 MA/cm² (4.2 K) and 1.6 MA/cm² (77 K) were achieved. The reduction of the superconducting volume corresponding to the amorphous radiation defects did not exceed 4% from the total sample volume.

The microstructure of GdBa₂Cu₃O_7−δ based on superconducting tapes with BaSnO₃ and BaZrO₃ artificial pinning centers formed by high-rate pulse laser deposition in SuperOx Japan was studied by scanning/transmission electron microscopy. The artificial pinning centers have adopted columnar morphology with average diameter of about 8 nm (BaSnO₃-doped sample) and 6.5 nm (BaZrO₃-doped sample) and density of 500 μm⁻² for the both samples. The average length of the BaSnO₃ nanocolumns is about two times higher than the BaZrO₃ nanocolumns. The angular dependences of critical current in magnetic field up to 1 Tesla at 77 and 65 K have been obtained. The critical current and its anisotropy depend on artificial pinning centers presence and their type. The angular dependence of resistivity in the field up to 9 Tesla was also studied and discussed.

In the stoichiometric iron-based superconductor EuRbFe₄As₄, superconductivity coexists with a long-range magnetic ordering in Eu layers. Using high-resolution transmission electron microscopy (HRTEM), we observed an atomic structure of as-grown EuRbFe₄As₄ crystals. HRTEM shows that crystals have two-dimensional intrinsic nanoinclusions established to be the RbFe₂As₂ (122) phase with a volume fraction of ~5.6%. In contrast with the CaKFe₄As₄ compound, similar inclusions are not superconducting down to 2 K, and no second magnetization peak was observed in the magnetization measurements at low temperature with B ‖ ab. We show that the non-superconducting 122 phase nanoinclusions could act as 2D pinning centers.

In this work, we present a study of the resistive transition in magnetic field of 2G high-temperature superconductor wire samples with BaSnO ₃ (BSO) artificial pinning centres (APCs) in a GdBa ₂ Cu ₃ O _7−x (GdBCO) superconductor. The GdBCO layer was fabricated by pulsed laser deposition, using production equipment to obtain samples with varied concentrations of APC: 0, 6, 12 and 18 mol% of BSO. Resistive transition curves were measured in the magnetic field range from 0 to 9 T, and magnetic field orientations from B∣∣ c ( θ = 0°) to B∣∣ ab ( θ = 90°) with an angle step of 15°. We observed an irreversibility temperature peak at the B∣∣ ab orientation. We determined the angular regions where correlated pinning centres dominated and found them to expand with the increase of BSO concentration. The activation energy ( U _a ) obtained from the lg( ρ/ρ ₀ ) against the 1/ T plots was almost constant in the whole angular range, with a small peak at B∣∣ ab . The activation energy as well as the irreversibility temperature decreased with the increasing doping level, but the U _a ( θ ) curves looked similar for all samples with APCs. The logarithmic resistivity plot of the undoped sample looked substantially different from those of the APC samples, with a kink and two different slopes corresponding to two regions with different U _a . We discuss that this difference is related to the different pinning landscapes in samples with and without APCs.