O17NMR spectroscopy ofBi2Sr2CaCu2O8+xhigh-Tcsuperconductor

We have investigated at room temperature and at 7 K the ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ NMR spectrum of a chemically and structurally characterized ${}_{}{}^{17}{}_{}{}^{}\mathrm{enriched}$ powder of ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_{8+\mathit{x}}$ superconductor. Using the frequency dependence of the spectrum and ${\mathit{T}}_1$ relaxation-time measurements, we were able to infer that the two lines constituting the spectra can be assigned to the oxygen nuclei in the SrO planes and to the oxygen nuclei in the ${\mathrm{CuO}}_2$ planes. The absence of the expected BiO line is accounted for, on the basis of the incommensurate superstructure existing in these compounds.