Thickness effect of Gd2Zr2O7 buffer layer on performance of YBa2Cu3O7−δ coated conductors

• Highly biaxial textured Gd2Zr2O7/Y2O3 structure was prepared on NiW tape.
• The optimized thickness of Gd2Zr2O7 buffer layer was reduced by over a half.
• The deterioration of microstructure on GZO exceeding 120 nm was proved by RHEED.
• We obtained Tc and Jc as 92 K and 0.5 MA/cm2 on the YBCO prepared on optimized GZO.

Bilayer buffer architecture of Gd2Zr2O7 (GZO)/Y2O3 was prepared on the biaxially textured tape of Ni–5 at% W (NiW) by reactive sputtering deposition technique. The buffer layer of GZO films were deposited with different thicknesses on Y2O3 seeding layer with a given thickness of 20 nm. According to the results of φ-scan, the in-plane FWHMs of GZO films decreased and then reversed with increasing thickness of GZO, which corresponded with the in-plane FWHMs and superconducting properties of YBa2Cu3O7−δ (YBCO) films. Reflection High-Energy Electron Diffraction (RHEED) was carried out to examine the surface texture of GZO films and the deteriorated surface alignment was found for thicker films. The thickness effect of GZO on performance of YBCO is the coupling result of surface texture and blocking effect caused by thickness. With the balance of these two factors, the YBCO/GZO(120 nm)/Y2O3/NiW architecture exhibit relatively high performance with the transition temperature Tc of 92 K, a transition width ΔTc below 1 K, and a critical current density Jc of 0.65 MA/cm2.