Influence of polyurethane skeleton on structural and superconducting properties of Y-123 foams

Abstract

The physicochemical properties of Y-123 superconducting foams of various topologies prepared by the top-seeded infiltration-growth (TSIG) method are discussed. During the TSIG process, precursor foams (polyurethanes with various densities, flexibilities, and skeleton types) were infiltrated with a green phase (Y-211) and thermally converted to Y-123 superconductors using NdBCO single-crystal seeds oriented in the [100] direction. The occurrence of the desired superconducting phases were confirmed by X-ray diffraction, Raman and X-ray absorption spectroscopies as well as magnetometric and transport measurements. It was found that the growth of Y-123 foam preserves the crystallographic orientation of the NdBCO seed regardless of the initial alignment of the skeleton. The foams exhibit the critical temperature (Tc) similar to YBCO bulk. High-density and stiffness skeletons favor the Y-123 phase formation, while more flexible foam structures hamper transformation of the Y-211 phase into the Y-123 one.