Thermally stimulated luminescence applied to high-temperature superconductivity research

It was recognized shortly after the discovery of high-temperature superconductors (HTS) that these materials would exhibit thermally stimulated luminescence (TSL) as a manifestation of their granularity and consequent inclusion of insulating material at grain boundaries. The large optical absorption coefficients of these opaque materials implies that TSL emanates from within ∼1 μm of the surface. Therefore, TSL can be used to assess the quality of HTS by detecting the presence of insulating surface impurities, which are, in general, deleterious to technological performance. For example, surface resistance Rs is determined by HTS properties within the London penetration depth, which is the region probed by TSL. The presence of insulating surface impurities contributes to the high-frequency losses as manifested by an enhanced Rs and is directly correlated with TSL. Therefore, in addition to radiation dosimetry and archaeological dating, TSL can also be applied to HTS research. © 1991