Moissanite anvil cell single crystal NMR at pressures of up to 4.4 GPa

High-pressure anvil cell nuclear magnetic resonance (NMR) studies of single crystals are challenging, but they can offer much insight into material properties. A microcoil inside the high-pressure region that encloses the crystal offers a good signal-to-noise ratio, but special care has to be taken to warrant hydrostatic conditions or to avoid rupture of the crystal or coil. By introducing precise monitoring of the height and diameter of the pressurized sample chamber, this can be ensured, and the data reveal the behavior of the sample chamber under pressure. While its total volume is given by the compression of the enclosed pressure transmitting fluid, the aspect ratio of the cylindrical chamber changes considerably. ⁶³Cu and ¹⁷O NMR of two differently doped single crystals of YBa₂Cu₃O_7-δ at pressures of up to about 4.4 GPa show the function of the cell, and orientation dependent spectra prove the soundness of the arrangement.