Expansion of the pressure range of Kawai-type multi-anvil presses (KMAPs) with tungsten carbide (WC) anvils is called for, especially in the field of Earth science. However, no significant progress in pressure generation has been made for 40 years. Our recent studies have expanded the pressure generation of a KMAP with WC anvils to 65 GPa, which is the world record for high-pressure generation in this device and is more than 2.5 times higher than conventional pressure generation. We have also successfully generated pressures of about 50 GPa at high temperatures. This work reviews our recently developed technology for high-pressure generation. High-pressure generation at room temperature and at high temperature was attained by integration of the following techniques: (1) a precisely aligned guide-block system, (2) a high degree of hardness of the second-stage anvils, (3) tapering of the second-stage anvil faces, (4) a high-pressure cell consisting of materials with a high bulk modulus, and (5) high thermal insulation of the furnace. Our high-pressure technology will facilitate investigation of the phase stability and physical properties of materials under the conditions of the upper part of the lower mantle, and will permit the synthesis and characterization of novel materials.

Ishii, T., Liu, Z., Katsura, T., A Breakthrough in pressure generation by a Kawai-type multi-anvil apparatus with tungsten carbide anvils, Engineering 5, 434-440, 2019. doi.org/10.1016/j.eng.2019.01.013