Gearbox designs for the diamond anvil cell: Applications to hard-to-reach-places

The uniaxial compression design of the diamond anvil high pressure cell (DAC) necessitates the use of a soft pressure-transmitting medium (PTM) to minimize non-hydrostatic effects at significantly high pressures, and many such media are gaseous at ambient conditions. There now exist a number of commercially-available instruments - high-pressure gas loading apparatus - for the insertion of gases into the diamond anvil cell up to several kbar. These machines allow the use of gases as a PTM, as a reagent for high-pressure chemistry, or to be loaded as the sample material itself. We present the development of two highly adaptable gearbox designs to allow the controlled closure of the DAC within an atmosphere of gas at several kbar, contained within the walls of a pressure vessel. The first applies a torque directly to the pressure screws and is thus DAC-specific, while the second applies a load to the body of the cell and may be used with a wide variety of DAC designs.