Elucidation of YBCO Growth Mechanism in KOH Flux Method

Abstract

In this work, we present an extremely low-temperature (600 °C) liquid-phase synthesis method using KOH as flux to grow YBCO powder and epitaxial films. Oxides utilize solution medium KOH in which target materials are generated by cation’s physical and chemical transformations. Y123 and Y124 films could be synthesized by controlling configuration which is related to oxygen diffusion. Later, the process and mechanism of YBCO growth will be elucidated by DSC. In the presence of KOH, the decarboxylation of BaCO3 is kinetically favored with the formation of Ba (OH)2 at the first step, the same as Y2O3 and CuO. Above 350 °C, the formation of Y2Cu2O5 will take precedence over Ba2Cu3O5 due to the weak solubility of Y3+ and Cu2+ in molten KOH. With temperature increasing, liquid Ba(OH)2 begins to dehydrate, and Ba2+ subsequently reacts with Y3+ and Cu2+ to precipitate YBCO in the last step. Molten KOH provides a liquid chemical environment, which allows the synthesis of YBCO at low temperature. This low-temperature method is applicable to epitaxial superconductor and superconducting joint.