Abstract
The pressure range of single crystal structure determination using a sealed source was extended to over 30 GPa with the improved techniques in this study. Rare gas solid helium was found to be the only pressure medium that can secure hydrostatic environment to very high pressure. The solid argon or neon induces significant divitoric stresses in crystals at relatively low pressure. The crystal volume was doubled at certain targeting pressure by using a new gasket material. The intrinsic background of a pressure cell was significantly reduced by a special collimator. These procedures improved the signal/noise ratio to 3 - 4 times. The quality of the structure refinement and the accuracy of atomic coordinates at 33 GPa are comparable with measurements at ambient conditions in a diamond cell.
