Comparison Study of the Flux Pinning Enhancement of YBa2Cu3O7−δ Thin Films With BaHfO3 + Y2O3 Single- and Mixed-Phase Additions

Incorporating nano-scale insulating phases to YBa
₂
Cu
₃
O
_7-δ
(YBCO) superconductor thin films enhances flux pinning by combining different pinning mechanisms, which in turn increases the current density. This research explores the effects of addition of the non-reactive phases of barium hafnate (BHO) and yttrium oxide Y
₂
O
₃
. Pulsed laser deposition (PLD) produces thin films on SrTiO
₃
(STO) substrates at various deposition temperatures ranging from 790 °C to 840 °C. PLD target compositions vary the volume percent of BHO from 2 to 6 vol% while maintaining 3 vol% Y
₂
O
₃
and the remaining vol% YBCO. Examining the microstructure through SEM, TEM, and XRD analyses provides insight into the impact of the additions of BHO and Y
₂
O
₃
on the YBCO thin films' magnetic and transport current densities measured with an applied field parallel to the c and ab directions, and on the films' critical temperature measurements. The Y
₂
O
₃
additions decrease the variability in the current density between the c and ab directions, which is an important aspect to consider in applications, such as for HTS wires for motors.