In situstudy through electrical resistance of growth rate of trifluoroacetate-based solution-derived YBa₂Cu₃O₇films

Abstract

In this work, we have studied by means of in situ electrical measurements the nucleation, growth and sintering stages of epitaxial YBa 2 Cu 3 O 6+δ (YBCO) superconducting thin films prepared using a chemical solution deposition approach based on metal-organic trifluoroacetate-based (TFA) precursors. Single crystal substrates (LaAlO 3 and CeO 2 /YSZ) were used in this study. Analysis of isothermal time dependences, at different temperatures, of in situ electrical resistance of films allowed to evidence that the growth rate G is strongly temperature dependent, i.e. G is enhanced by a factor ∼15 when going from 700 to 810 °C. Additionally, we demonstrate that adding Ag-TFA in the solution may enhance the growth rate by as much as 50%, as compared to pure YBCO, thus confirming previous assessments of the strong influence of Ag doping on YBCO film growth and microstructure. In situ electrical resistance measurements show as well that an incubation time exists and we infer the origin of its temperature dependence. Finally, a thermodynamic analysis allows proposing a single equation for the growth rate of YBCO films integrating all the relevant processing parameters. Our analysis has validated the solid-gas reaction-diffusion model describing the growth of YBCO films from TFA precursors and thus enlarges the knowledge required to enhance the control of the microstructure and superconducting properties of solution-derived YBCO films.

Accelerated growth by flash heating of high critical current trifluoroacetate solution derived epitaxial superconducting YBa2Cu3O7 films

“…This allows the estimation of the YBCO growth rate along the c-axis. We have estimated for our FH films that the growth rates at P(H 2 O) = 23 mbar are 0.47 nm s À1 and 0.32 nm s À1 , at 810 1C and 750 1C, respectively, in agreement with the values determined in films grown by CTA, 46,47 deduced in both cases from in situ resistance measurements. 211, respectively, while the samples were quenched at 810 1C in a dry gas atmosphere (blue ), at 810 1C in a humid gas atmosphere (black K) and at 750 1C in a humid gas atmosphere (red ) after annealing for selected time periods.…”

“…respectively. These time periods are significantly decreased (by factors 3-5) as compared to the films grown by the CTA heating route, as detected by in situ electrical conductance measurements 39,46,47 or X-ray diffraction. 36,39 Very likely, the fundamental reason for such a reduced incubation time is the smaller atomic diffusion lengths needed to form stable nuclei which then enhances the nucleation rate.…”

Epitaxial YBa2Cu3O7−xnanocomposite thin films from colloidal solutions

“…1) has been reached at the present growth rate [62]. Of course, an equivalent approach to trap small nanoparticles is, as suggested by eq.…”

Untangling surface oxygen exchange effects in YBa2Cu3O6+x thin films by electrical conductivity relaxation

“…The subsequent pyrolysis and growth processes are also described elsewhere. [93][94][95] The phase analysis of the YBCO films was performed by X-ray diffraction using a Bruker AXS GADDS diffractometer equipped with a 2D detector. The lattice parameters were determined using a Siemens model D-5000 X-ray diffractometer with a step size of 0.011.…”

“…The films conductance was determined by electrical measurements carried out using a standard system reported elsewhere. 18,19,95,96 It consists of a 4-probe contact in a Van der Pauw configuration. The sample is held in the center of a 22 mm furnace tube that allows controlling the temperature and gas atmosphere.…”