Effect of fabrication conditions on crystalline of SmBCO films fabricated by TFA-MOD method

Abstract

Metal organic deposition using trifluoroacetates is expected as a method for YBCO coated conductors since this method can provide high superconducting properties and is a cost-effective process with non-vacuum system. Recently, REBCO coated conductors, which has high critical properties, have attracted considerable attention. However, there are some problems to optimize fabrication conditions of REBCO films with this method. In this study, we fabricated SmBCO films by TFA-MOD method and investigated the effect of fabrication conditions on crystalline. We focused especially on a starting temperature ( T 1) of inlet moisture in calcination step and O 2 gas concentration in crystallization step. Flat surfaces were obtained for the calcined films at both T 1 = 300 °C and 350 °C compared with that at 200 °C. One possible reason for this worse morphology at T 1 = 200 °C might be a length of a reaction time between moisture and coated film. When moisture is supplied from low temperature for long time, water could react easily to the fluoride which is contained a lot in the coated film; as a result, more HF gas is generated from the film. The crystalline was also improved for the SmBCO films calcined at over T 1 = 300 °C. Furthermore, the film calcined at T 1 = 350 °C was crystallized under the condition that O 2 gas concentration was varied between 0.2 ppm and 1000 ppm. The degree of c-axis orientation depends on oxygen partial pressure and the highest c-axis oriented SmBCO film was obtained in the case of 10 ppm.