Chemical synthesis and microstructural analysis of superconducting YBa₂Cu₃O_7-δ ink deposited by drop-on-demand ink-jet printing on silver substrates

Abstract

The basis for the development of computer controlled printing techniques for YBa₂Cu₃O_7-δ (YBCO) coated conductors is discussed in detail. This method of continuous deposition of YBCO material potentially enables non-vacuum formation of complex multi-layer superconducting patterns on silver substrates. Sol–ink processes were used to print single droplets of YBCO on polycrystalline silver substrates under varying printing conditions. Droplet sizes were controlled from a range of 300 μm–1200 μm. The formation and the stability of the sol–ink with respect to pH and concentration has been studied and discussed herein. For optimum results, the pH of the ink had to regulated to 6.5. Printing and substrate parameters that alter solid–liquid interface properties were also investigated such as ink concentration and surface roughness, the best results produced were with an ink concentration of 0.025 M on a polished silver surface. In order to control the flow properties of the sol media dynamic viscosities were determined. Characterisation by X-Ray Diffraction, Differential Thermal Analysis, Thermal Gravitometry and Scanning Electron Microscopy was used to examine the sol–ink samples, whilst AC susceptibility was used to assess the superconductivity of the printed samples where they were discovered to have a characteristic T _c of ∼83 K.