Size-controlled spontaneously segregated Ba₂YTaO₆nanoparticles in YBa₂Cu₃O₇nanocomposites obtained by chemical solution deposition

Abstract

We present a thorough study of the nucleation and growth processes of the solution-based YBa 2 Cu 3 O 7 -Ba 2 YTaO 6 (YBCO-BYTO) system, carried out with a view to controlling the characteristics of the BYTO phase to meet the requirements for specific power applications. Scanning transmission electron microscopy and x-ray diffraction have been used to characterize the BYTO nucleation and phase evolution during the YBCO-BYTO conversion. At high BYTO loads (>10 mol%), the nanoparticles tend to aggregate, resulting in much less efficiency for generating nanostrained areas in the YBCO matrix, and enhancement of the vortex pinning. Our experiments show that by modifying the nucleation kinetics and thermodynamics of the BYTO, the nucleation mode (homogeneous versus heterogeneous), the particle size and the particle orientation can be controlled. We demonstrate that YBCO-BYTO nanocomposites with high concentration of nanoparticles can be prepared in such a way as to obtain small and randomly oriented nanoparticles (i.e. high incoherent interface), generating highly strained nanoareas in the YBCO, with enhancement in the vortex pinning. We have also observed that the incoherent interface is not the only parameter controlling the nanostrain. The Cu-O intergrowth characteristics must also be a key factor for controlling the nanostrain in future tuning of YBCO vortex pinning.

Epitaxial YBa2Cu3O7−xnanocomposite thin films from colloidal solutions

“…This suggests that high NP loadings lead to random and thus poorly grown YBCO [31], which is also confirmed by the 2D-XRD patterns in Figure 10c. Furthermore, the 10 mol % ZrO 2 NPs-YBCO nanocomposite film shows the presence of BZO in the final layer, while ZrO 2 reflections remain absent (Figures 10a and 10b).…”

“…The analysis of the superconducting properties of the YBCO-16 mol % ZrO 2 nanocomposites enables us to conclude that T c = 90 K and J c sf (77 K) = 4 MA/cm 2 , thus reaching J c sf values of our best pristine samples, see Figure 15a [30,31]. The J c (H) dependence is rather rounded-like, as typically observed for in-situ CSD nanocomposites.…”

“…Therefore, tight control of the kinetics during the growth process will be required for fine tuning of the coarsening rate [31] and the defect structure associated to randomly oriented nanoparticles with a subsequent improvement of the pinning properties.…”

Angular flux creep contributions in YBa2Cu3O7−δ nanocomposites from electrical transport measurements

“…In this study, we present results obtained by electrical transport measurements on YBCO thin films grown by chemical solution deposition with and without the inclusion of nanoparticles in the YBCO matrix, whose growth details were reported previously 14 . We have studied nanocomposites from three different groups (I, II and III) as will be explained below, regarding their disparate concentrations of Stacking Faults (SFs) caused by distinct nanoparticle compositions and processing methods.…”

“…The decrease indicates the effect of correlated pinning centers hampering the vortex flux motion whereas the increase indicates favoring of thermal flux motion aided by the regular and recurring pinning centers. Notice that the effect in the nanostructure given by the insertion of nanoparticles is different depending on the nanoparticle composition and growth conditions commented in other works 14,28 . In nanocomposite D, a higher amount of SFs emerge from the incoherent interface between nanoparticles and YBCO, causing a stronger distortion of the CuO 2 planes and adding new pinning sites that turn out to be the dominant (see Supplementary Fig.…”