Cobalt-doped magnesium oxide pressure-transmitting medium for high pressure and high-temperature apparatus

Magnesium oxide (MgO) doped with cobalt (Co) semi-sintered pressure-transmitting medium (MCOPM) was prepared at 1200 degrees C in air, starting with a pre-compressed mixture of MgO and cobalt oxide (CoO). The samples were characterized using powder X-ray diffraction, scanning electron microscopy, and thermal conductivity measurements. The results demonstrate that during the sintering process, the exchange of metal ions between the mixture powders introduced lattice defects into the MgO lattice structure, and an MgO-CoO solid solution was formed. Compared to commercial semi-sintered MgO pressure-transmitting medium (SSMPM), the temperature-generation efficiency of MCOPM-17 (MgO+17mol% CoO) improved by about 220% at the high pressure of 12GPa with a cell assembly in a two-stage multi-anvil large volume press. Moreover, the thermal conductivity of CoO-doped MgO decreased with increasing CoO doping.