A study was made of C contamination from atmospheric sources during preparation of thermooxidized HTSC-layers on microcrystalline Y--Ba--Cu ribbons. Some correlation was found between the ...peculiarities of grain boundaries C contamination and the value of J sub C . The results of Auger scanning microscope microanalysis are correlated with resistivity and critical current values. The presence of graphite-like C in grain boundaries is concluded to be one of the reasons for the low value of the critical current in oxidic layers in microcrystalline Cu-based rapidly quenched ribbons. Graphs, Spectra. 9 ref.--AA
