Measurements of the thermal stresses in large-grain Y-Ba-Cu-O superconductors

Large single grain Y-Ba-Cu-O superconductors have significant potential for various industrial applications. However, large-grain Y-Ba-Cu-O experiences large forces due to its relatively low thermal conductivity during thermal cycles. The thermal stress arises mainly due to a large anisotropy in thermal conductivity between ab and c axes. In this paper, we attempted to measure the thermal stresses of large-grain Y-Ba-Cu-O during the cooling process from room temperature to 100 K using the strain gauges that are directly mounted onto the sample surface. It was found that the tensile strain increased along the c axis on cooling, which should be taken into account when handling large-grain samples.