NMR of H1 and D2 in hydrogen-doped and deuterium-doped YBa2Cu3O7

The hydrogen and deuterium nuclear-magnetic-resonance absorption lines were obtained for Hx(Dx)YBa2Cu3O7 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 H1 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 e2qQ/h of the order of 230 kHz and an asymmetry parameter of η0.05. While the pattern can be explained by a single D2 site, the nuclei represented by the wide portion of the H1 traces give a washed-out D2 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.