NMR ofH1andD2in hydrogen-doped and deuterium-dopedYBa2Cu3O7

The hydrogen and deuterium nuclear-magnetic-resonance absorption lines were obtained for ${\mathrm{H}}_{\mathit{x}}$(${\mathrm{D}}_{\mathit{x}}$)${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ where x=0.21, 0.60, and 1.00 for the hydrogen-doped samples and x=0.10, 0.20, 0.50, and 1.00 for the deuterium-doped samples. The ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ line shape was both temperature and hydrogen concentration dependent. While a relatively narrow line was seen for low hydrogen concentrations, a line of the order of 650 kHz emerged at higher concentrations. The quadrupole powder pattern of the deuterated sample was independent of the deuterium concentration and yielded only a single discernible line, having a quadrupole coupling constant ${\mathit{e}}^2$qQ/h of the order of 230 kHz and an asymmetry parameter of η≊0.05. While the pattern can be explained by a single ${}_{}{}^2{}_{}{}^{}\mathrm{D}$ site, the nuclei represented by the wide portion of the ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ traces give a washed-out ${}_{}{}^2{}_{}{}^{}\mathrm{D}$ quadrupolar pattern and a second site for these nuclei cannot be ruled out. A point-charge model using accepted values for the metal and oxygen charges gives results consistent with the deuterium (or hydrogen) being located between the O(1) chain oxygens and the O(4) bridging oxygens. All other sites proposed by various investigators yield quadrupole-coupling-constant values much smaller than that obtained in our measurements.