抄録
In the molten hydroxide method using potassium hydroxide as a flux, Nd/Ba substitution was suppressed by reducing the oxygen concentration in the solution, enabling low-temperature synthesis of Nd123 epitaxial films with high Tc. When using several Cu raw materials with different oxygen contents, employing metal Cu with lowest oxygen content resulted in Nd123 films with higher Tc. However, compared to conventional bulk Nd123 without Nd/Ba substitution, the Tc was still lower. Using metal Cu as the Cu raw material and employing a solution with an even lower oxygen concentration by bubbling with N2 gas, an Nd123 film with a Tc of 93 K, comparable to the bulk Tc value, was obtained at a low synthesis temperature of 550ºC. Furthermore, the reduction in synthesis temperature and deposition time also minimized elemental diffusion from the substrate and improved film homogeneity.
