O-17 NMR IN HIGH-T-C SUPERCONDUCTOR TL2BA2CACU2OY

O-17 NMR measurements have been performed between 10 and 400 K on an o verdoped sample of Tl2Ba2CaCu2Oy (T-c = 103 K). The electric field gra dient parameters were deduced for all the oxygen sites. The temperatur e dependence of the magnetic hyperfine shift was measured for all thes e sites. No thermal variation of the shift was detected down to T-c fo r oxygen in the TlO reservoir plane. As for oxygen in the CuO2 plane t he temperature dependence of the shift is similar to that for Tl-205 N MR line from thallium defects in the Ca layer measured in the same pow der sample. This similarity is consistent with the single spin fluid m odel. The spin contribution to K-17(iso)(T) and magnetic hyperfine con stant (17)A(iso) were deduced.