Controllable rectification on the thermal conductivity of porous YBa₂Cu₃O_{7− x} superconductors from 3D-printing

Abstract

Superconducting YBa2Cu3O7-x (YBCO) bulks have promising applications in quasi-permanent magnets, levitation, etc. Recently, a new way of fabricating porous YBCO bulks named Direct-Ink-Writing (DIW) based 3D-printing process has been reported. In this method, customized precursor paste and programmable shape are the two main advantages. Here, we have put forward a new way to customize the YBCO 3D-printing precursor paste which is doped with Al2O3 nano particles to obtain YBCO with higher thermal conductivity. The great rheological properties of precursor paste after doped with Al2O3 nano particles helped the macroscopic YBCO samples with high thermal conductivity being fabricated stably with high crystalline and lightweight properties. Test results shows that the peak thermal conductivity of Al2O3 doped YBCO with larger thermal conductivity can reach twice as much as pure YBCO, which made great effort to reduce the quench propagation speed significantly. Based on analysis of this YBCO with larger thermal conductivity’s microstructure, one can find that the thermal conductivity of doped YBCO would be determined not only by its components but also by the microstructure. We have proposed a macroscopic theoretical model to assess the thermal conductivity of different microstructures. One can find that the calculated results take good agreement with the experimental results. Meanwhile, a microstructure with high thermal conductivity is found. At last, we have designed a macroscopic YBCO structure, which is made up with the presented high thermal conductivity microstructure, fabricated by the DIW 3D-printing process. Compared with the traditional 3D-printed YBCO, the structural designed samples make a great effort to further enhance thermal conductivity of YBCO. Our customized design of 3D-printing precursor pastes and novel concept of structural design for enhancing thermal conductivity of YBCO superconducting material can be widely used in other materials which are suitable for the DIW 3D-printing process.