Microstructures and critical current densities of YBCO films containing structure-controlled BaZrO₃nanorods

Abstract

BaZrO3 nanorods are known to be effective pinning centers as c-axis-correlated pinning centers. Furthermore, BaZrO3 nanorods in REBa2Cu3Oy (RE: rare-earth element) films are formed by self-assembled stacking of BaZrO3 using a target mixture of a superconductor and BaZrO3 for pulsed-laser deposition, which is a very easy fabrication technique. The density of BaZrO3 nanorods in YBa2Cu3Oy (YBCO) films can be controlled by varying the BaZrO3 content in a target. The BaZrO3 addition has two functions for superconductivity; one is the improvement of pinning forces due to the addition of pinning centers and the other is Tc degradation. The optimum BaZrO3 addition for Jc improvement in magnetic fields is found to be around 3 wt% because of a trade-off between the two functions described above. Furthermore, the length of BaZrO3 nanorods is found to be controlled using two types of target: pure YBCO and a mixture of YBCO and BaZrO3. Varying the BaZrO3 nanorod length has an effect on the pinning mechanism. In particular, magnetic field angle dependences of Jc are varied from c-axis-correlated pinning to nearly random pinning by changing the nanorod length. The magnetic field at the crossover of the pinning mechanism seems to be adjusted by the BaZrO3 nanorod length.

Structural and magnetic properties of YBa2Cu3O7/BaZrO3 composites

“…Another extensively used substrate for YBCO, LaAlO 3 , exhibits an excellent lattice coupling but it has the disadvantage of being available only as twinned single-crystal 6 . Studies on the effect of BaZrO 3 on YBa 2 Cu 3 O 7 superconducting thin films as pinning centers in order to improve the critical current density have been reported 7 . A microstructural analysis of the BaZrO 3 as potential substrate for YBa 2 Cu 3 O 7 films was performed without consider it effect on the superconducting properties 8 .…”

Improvement in Jc performance below liquid nitrogen temperature for SmBa2Cu3Oy superconducting films with BaHfO3 nano-rods controlled by low-temperature growth

“…The number density of defects in the REBCO matrix can be increased by increasing the BMO doping level, [15][16][17][18] lowering the growth temperature during deposition, 3,18,19 and using the optimal type of BMO materials. 6 In order to apply REBCO CCs to coil-based applications, isotropic improvement of their J c performance (under a magnetic field) at the operating conditions is required.…”

Energy and superconductors – applications of high-temperature-superconductors

“…The introduction of artificial pinning centers into the HTS material is therefore one of the basic challenges in HTS materials development in order to prevent flux flow in the HTS wires under operation and thus increase the upper critical field H c2 [10]. The pinning centers can be introduced by nano-precipites during crystallisation, by direct implementation of nano-particles [11] and by co-crystallization of normal conducting nano-columns [12]. This development is still ongoing and one of the most active research fields worldwide.…”