Detection of surface (∼1 μm) impurity phases in high Tc superconductors


We show that thermally stimulated luminescence is an important method for detecting insulating impurity phases that commonly occur in high Tc superconductors. The technique is sensitive to impurity phases at <1% level with a probe depth of ∼ 1 μm, which is the region of interest for many superconductor applications. Samples of Y2O3, Y 2BaCuO5, YBa2Cu3O6.2, BaCO3, Ba3CuO4, BaCuO2, and YBa 2Cu3Ox (x≊7) were investigated. All but the high quality sintered pellets of YBa2Cu3Ox exhibited relatively intense luminescence. The absence of luminescence, and thus of insulating phases, is correlated with low values of rf surface resistance.

Publication Title

Applied Physics Letters