Fabrication, characterization, and theoretical analysis of high-T c Y-Ba-Cu-O superconducting films prepared by a chemical sol gel method

Abstract

Thin films of Y1Ba2Cu3O7−x have been produced on MgO substrates by a chemical sol gel method. X-ray diffraction data indicate that the annealed films have the characteristic orthorhombic structure with lattice constants which are nearly the same as the values reported for the bulk specimen of Y1Ba2Cu3O7−x. Auger electron spectroscopy depth profiling measurements indicate that the films are uniform in thickness and composition. Measurements of electrical resistance of films 1–4.7 μm in thickness have been carried out between 12 and 300 K using a standard four-probe geometry. The films are superconducting with an onset temperature around 95 K and a full transition temperature as high as 79.5 K, and a critical current density of 2700 A/cm2 at 20 K. A theoretical analysis of the critical current density in Y1Ba2Cu3O7−x as a function of temperature has been made in order to determine the characteristics of the junctions between the superconducting grains. Theoretical models which describe the dependence of the critical current density on temperature have been presented and agreement has been found between these models and experimental values for sol gel films. The critical transport current has a temperature dependence which is characteristic of superconductor-normal metal-superconductor (S-N-S) type junctions. The magnitude of the resistance and thickness of the junctions has been determined from the theoretical models. Information regarding calculation of the oxygen content in Y1Ba2Cu3O7−x films is also presented.

Development of Large Scale YBa2Cu3O7-x Superconductor with Plastic Forming

“…This limits the size of the samples that can be produced. For thin films, several methods have been used such as the sol-gel method [4], metalorganic chemical vapor deposition (MOCVD) [5], pulsed laser deposition [6]. However, it is difficult to produce thick and large samples with various three-dimensional structures by these methods.…”

Characterization of a Large‐Scale Nondoped YBa2Cu3O7−x Superconductor Prepared by Plastic Forming Without High‐Pressure Molding

“…This limits the size of the samples that can be produced. For thin films, several methods have been used such as the sol–gel method, 10 metalorganic chemical vapor deposition (MOCVD), 11 coating pyrolysis, 12 and pulsed laser deposition 13 . However, it is difficult to produce thick samples with various three‐dimensional structures by these methods.…”

Ultrathin Aluminosilicate Films from Langmuir−Blodgett Multilayers

“…The composition of some LB films is similar to the starting mixture in the standard sol−gel technique for the preparation of metal oxides, the final composition and structure of the oxide being determined by the firing conditions and subsequent anneal. While LB films have been used as precursors for the preparation of oxide films, their potential for forming ceramic and zeolite-type structures does not seem to have received much attention.…”