Artificial Nano-Scale Precipitates for Flux Pinning in YBa2Cu3O7-δ Thin Films and Coated Conductors
By controlling pulse number of laser ablation, we prepared a series of quasi-multilayers of YBa2Cu3O7-δ/M (M=incomplete oxide layer) namely 70×(40/n) (n = 2, 5, 10 and 20, pulse number of M) which were characterised with nano-scale precipitates. While the texture properties of Y123 inside qusi-multilayer hardly change, its Tc appeared much different depending on the doping level of M. X-ray θ-2θ scanning and pole figures indicated that the different growth-controlled precipitates occured inside Y123 films. In the case of M=YSZ (Yttria Stabilized Zirconia), nanosized perovskite precipitates of BaZrO3 formed as a result of solid state reaction of YSZ with Y123, leading to Tc obviously decreasing with increasing of n. In the case of M=Y2O3, however, Tc did not decrease so much at the studied range of n due to no solid state reaction mentioned above. Magneto-transport and field angular dependence showed that the critical current density in films with lower doping content (such as n = 2) was improved in large ranges of field and temperature, suggesting tailorable enhancement and anisotropy of flux pinning force.
Yafang Han et al.
C. Cai et al., "Artificial Nano-Scale Precipitates for Flux Pinning in YBa2Cu3O7-δ Thin Films and Coated Conductors", Materials Science Forum, Vols. 546-549, pp. 1865-1870, 2007