The REBa2Cu3Oy (RE: rare earth element) superconductors are one of the most promising materials for superconducting magnetic applications because of their high critical temperature (Tc) and critical current density (Jc). However, the Jc decreases significantly with increasing magnetic field due to the motion of vortices. Previously, we have shown a large enhancement in Jc at not only self-field, but also in-field, by introducing a high density of incoherent BaHfO3 nanoparticles (BHO NPs) of a tailored size into (Y0.77Gd0.23)Ba2Cu3Oy ((Y,Gd)123) coated conductors (CCs) grown by the Trifluoroacetate Metal Organic Deposition (TFA-MOD) method, which leaves the matrix unaltered and with just slightly decreased superconducting properties [1,2]. By introducing an intermediate heat treatment (IHT) before the conversion process, we successfully controlled the size of BaMO3 NPs compared to that without IHT [3].
In this work, in order to investigate the influence of the IHT temperature (TIHT) on the in-field superconducting properties, we fabricated BHO doped (Y,Gd)BCO CCs using various TIHT. All CCs show almost the same crystallinity and Tc. On the other hand, the BHO doped (Y,Gd)BCO CC with TIHT=570oC shows a higher self-field and in-field Jc and a less angular dependent Jc compared to those with other TIHT. Our results demonstrate that controlling the IHT temperature is an important way for controlling the size and density of BHO NPs and improving the in-field Jc of TFA-MOD CCs. Detailed in-field Jc properties and the microstructures of BHO doped (Y,Gd)BCO CC with various TIHT will be presented.
[1] M. Miura et. al., NPG Asia Materials 9 (2017) e447.
[2] M. Miura et. al., NPG Asia Materials 14 (2022) 85.
[3] K. Nakaoka et al., IEEE Trans. Appl. Supercond. 26 (2016) 800304.
This work was supported by JST-FOREST (Grant Number JPMJFR202G). A part of this work at Seikei University was supported by JSPS KAKENHI (23H01453 and 23KK0073).
Keywords: REBCO, YGdBCO, TFA-MOD, IHT, Jc, BHO, pinning center, nanoparticle