A phase relation study of Ba–Y–Cu–O coated-conductor films using the combinatorial approach

Abstract

Phase relationships in bulk and thin film Ba–Y–Cu–O high-Tc superconductor system were determined at processing conditions relevant for industrial production of coated conductors. Our results demonstrated that the absence of BaY2CuO5 (which has a critical effect on flux pinning) at 735 °C—a typical temperature employed in production of coated conductors—in thin films processed in situ from the BaF2 precursor is caused by the sluggish reaction kinetics rather than by the presence of fluorine in the system. Thermodynamic calculations combined with annealing experiments confirmed that BaY2CuO5 is thermodynamically stable but forms at temperatures higher than 735 °C.

Scanning SQUID Microscopy of Local Superconductivity in Inhomogeneous Combinatorial Ceramics

“…Y 2 BaCuO 5 has a critical effect on flux pinning and could form beside (123) when the yttrium concentration is low or the barium concentration is limited in the starting composition. [21,22] Single-grain SQUID measurements confirmed a T c value close to 92 K.…”

Evaluation of the Current Status of the Combinatorial Approach for the Study of Phase Diagrams

“… Ba-Y-Cu-O diagram [ 63 , 64 ] Application of the second-phase precipitation method for flux pinning in coated conductors requires accurate knowledge of the nature of phases that are compatible with Ba 2 YCu 3 O 6+x under relevant processing conditions. Figure 9 summarizes phase relationships for the Ba-Y-Cu-O system as deduced from our combinatorial experiments on compositional spreads [ 63 ], in situ XRD experiments on BaF 2 -based films, X-ray diffraction studies of a BaY 2 CuO 5 bulk sample, and our previous phase equilibrium work [ 64 ]. In this diagram, dotted tie-lines refer to T < 800 °C ( p O2 ≈ 100 Pa ) whereas solid lines corresponds to the temperature range between 800 °C to 850 °C ( p O2 ≈ 100 Pa ).…”

“… Phase relationships constructed based on results from the combinatorial synthesis approach (BaCuO 2 , Y 2 O 3 and CuO as targets on substrates SrTiO 3 and RABiTS), HTXRD experiments on a film with nominal composition of Ba:Y:Cu ≈ 1:2;1, and X-ray diffraction studies of the BaY 2 CuO 5 bulk sample; dotted-lines (T < 800 °C, ≈ 100 Pa p O2 ) and solid lines (T ≈ 800 °C to 850 °C (≈ 100 Pa p O2 )) [ 63 ]. …”

Combinatorial search of superconductivity in Fe-B composition spreads

“…[8][9][10][11][12] Combinatorial libraries 13 and composition spreads have also been used in the past to demonstrate simultaneous synthesis of multiple superconducting compounds as well as to map compositional phase diagrams of known superconductors. [14][15][16] Fe and B targets were co-sputtered to generate mapping of a large fraction of the binary compositional phase space across 3" Si wafers with a 200 nm SiO 2 layer on top. Fe and B were sputtered at 10 W (DC) and 100 W (RF), respectively.…”