Ionic alkalihalides as pressure media in DAC experiments

In Diamond Anvil Cells (DACs), usually a pressure transmitting medium functions to transform the uniaxial pressure supplied by the opposing diamond anvils into uniform hydrostatic pressure acting on the sample. Conventionally, a 4-1 methanol-ethanol solution, or a 16-3-1 methanol-ethanol-water solution is used as pressure transmitting medium. However, these two solutions transform into a glass with high elastic shear strength at pressures around 12-14 GPa and no longer function as hydrostatic medium. Our goal was to determine if liquid ionic alkalihalide alkanolate complexes will provide more uniform pressure in the cell up to 20 GPa. Ruby (Cr-doped AlP,) produces two Cr + fluorescence lines when exposed to sufficiently energetic radiation(457.9 nm in our case). These two fluorescence lines shift toward the IR with increasing pressure. We used the splitting of the two fluorescence lines as well as the width of the peaks in order to measure the shear strength of the alkalihalide alkanolate as a function of pressure