Performance of semi-sintered ceramics as pressure-transmitting media up to 30 GPa

Semi-sintered MgO- and ZrO2-based ceramics are the conventional materials used as a pressure-transmitting medium (PM) for large-volume high-pressure experiments. Our experimental data for both MgO and ZrO2 provide similar pressure generation efficiency. The major requirement for a PM material is low compressibility. However, our experimental data suggest that semi-sintered types of these ceramics are more compressible than can be expected. For instance, the apparent compressibility of semi-sintered magnesia is 35% and 60% higher than the lattice compressibility of MgO at 15 and 30 GPa, respectively. The difference in lattice and apparent compressibilities of semi-sintered ceramics is most probably caused by a residual porosity. The use of a low-porous pressure medium should be considered as an improvement of pressure generation efficiency of high-pressure apparatuses.