Accelerated growth by flash heating of high critical current trifluoroacetate solution derived epitaxial superconducting YBa2Cu3O7 films
Trifluoroacetate solution derived epitaxial YBa2Cu3O7 film growth is a high throughput cost-effective approach to preparation of high critical current superconducting materials for power applications. Nonetheless, controlling the kinetic transformation of a multiphasic (Ba1−xYxF2+x, CuO) polycrystalline state to an epitaxial film requires preserving at the nanoscale the initial molecular homogeneity of the solutions. Here we present a flash heating approach (∼30 times faster than conventional thermal annealing) to preparation of epitaxial films. We investigate through X-ray diffraction and TEM images the compositional and microstructural evolution at the nanoscale and we disclose how the nucleation rate is enhanced (3–5 times faster than conventional thermal annealing). We conclude that minimizing the coarsening of the intermediate nanocrystalline phases has a very positive role in accelerating the total required growth process, as well as in decreasing the growth temperature to achieve high quality epitaxy and microstructure. An additional advantage of the flash heating process is an increase of the density of nanometric defects (intergrowths), making a positive contribution to enhancing the vortex pinning efficiency and increasing the high magnetic field critical current density. Overall, implementing the flash heating process to grow YBa2Cu3O7 films appears to be a very promising opportunity to reduce the cost/performance ratio of high temperature superconducting materials because it reduces the growth time and it enhances their performance.