High pinning performance of YBa₂Cu₃O_7−xfilms added with Y₂O₃nanoparticulate defects

Abstract

We report the epitaxial growth and superconducting properties of Y2O3-added YBa2Cu3Ox (YBCO) films grown on SrTiO3-buffered MgO substrates by pulsed-laser deposition using surface-modified YBCO targets. Areas of Y2O3 sectors on the YBCO target were increased to 5.44% and 9.22% of the total YBCO pellet in order to find a correlation between the Y2O3 content, morphology, and the pinning properties of YBCO+Y2O3 mixed films. The maximum global pinning forces, FP, at 77 K were 14.3 GN m−3 and 1.15 GN m−3 for the Y2O3 5.44A% and 9.22A%, respectively. The 5.44A% Y2O3-added sample presents a very high value of pinning force at 77 K, approaching the value obtained in YBCO films with added BaZrO3 nanorods, but with less depression in the superconducting critical temperature, Tc. In accordance with scanning transmission electron microscopy (STEM) observations, both films present nanoparticulate Y2O3 dispersed in a YBCO matrix where Y2Ba4Cu8O16 (Y248) intergrowths were also observed. Consistent with the strong pinning theory, the size and distribution of randomly dispersed Y2O3 particles are optimal for the flux pinning of a 5.44A% Y2O3-YBCO film, while in the case of a 9.22A% film, the YBCO matrix is degraded by jampacked Y248 intergrowth, which leads to a comparatively poor pinning performance. We further used the single-vortex dynamics model to account for vortex pinning in the samples. The 5.44A% Y2O3-YBCO film result shows good agreement with the model fit up to 4 T of the applied magnetic field.

Local strain-driven migration of oxygen vacancies to apical sites in YBa2Cu3O7−x

“…The presence of this lattice defect is highly desirable as it contributes to the pinning of the magnetic flux vortices and enhances the physical properties of YBCO. 37,[41][42][43][44][45][46][47] However, its structure and chemistry is complex, 1,48 as the system forms Cu and O vacancies buried within the very same intergrowth in order to balance the stoichiometry when an extra CuO x layer is inserted in the YBCO structure. Gazquez et al reported that the most favorable vacancy configuration was the one containing two Cu vacancies accompanied with three O vacancies (2V Cu + 3V O ), with one O vacancy located in the upper CuO chain and two in the lower one, 1 as illustrated in Fig.…”

Tuning nanoparticle size for enhanced functionality in perovskite thin films deposited by metal organic deposition

“…Incoherent fine NP in MOD films Part of the successful addition of NPs in MOD can be found in Figure 3 by comparing the structural and superconducting properties for inclusions with coherent and incoherent interfaces, that is, coherent NRs in films grown using a low-temperature growth technique via PLD (PLD-BHO-NRs), 20 coherent nanoparticles (PLD-Y 2 O 3 -NPs) 38 and incoherent nanoparticles (MOD-BHO-NPs (d coat = 30 nm)). For both PLD films, the c-axis length of the superconducting matrix lattice expands markedly with increasing vol.% but, in contrast, remains flat for MOD-BHO-NPs.…”

Strong-pinning regimes by spherical inclusions in anisotropic type-II superconductors

“…Incorporating self-assembled inclusions into high-temperature superconductors has been established as a very efficient route to enhance their critical currents. Depending on the fabrication process, these inclusions may be prepared in the form of almost spherical particles [1][2][3][4][5][6][7][8][9][10], nanorods [11,12], or combinations thereof [13,14]. This technology is implemented in today's second-generation superconducting wires based on rare-earth barium copper oxide (REBa 2 Cu 3 O 7 or RE-BCO) coated conductors [15,16], where the rare earth (RE) is mostly yttrium (Y) or gadolinium (Gd).…”