O17 NMR spectroscopy of magnetically ordered YBa2Cu3O7-x microcrystals

We have obtained O17 nuclear-magnetic-resonance spectra of powder samples of YBa2Cu3O7-x and EuBa2Cu3O7-x, as well as magnetically ordered YBa2Cu3O7-x. Two major features are observed in YBa2Cu3O7-x: a sharp resonance at 1800 ppm (from external H217O, International Union of Pure and Applied Chemistry scale) and a broader series of features centered at 400 ppm. The 1800-ppm feature undergoes a diamagnetic shift of 800 ppm on cooling to 77 K, and a similar magnitude shift on Eu substitution, suggesting assignment to the plane oxygens, O(2,3). Measurements on magnetically ordered samples at 8.45 and 11.7 T give the magnitude of the diagonal terms of the electric-field-gradient tensor, which are 2.3, 3.5, and 5.8 MHz. For the column oxygen, O(1), we find e2qQh=7.7 MHz, with a chemical shift anisotropy of 660 ppm.