Diamond anvil cell and high-pressure physical investigations

The present status of high-pressure research with the diamond anvil cell (DAC) is reviewed in this article, mainly from an experimental aspect. After a brief description of the different types of DAC's that are currently in vogue, the techniques used in conjunction with the DAC in modern high-pressure research are presented. These include techniques for low- and high-temperature studies, x-ray diffractometry, spectroscopy with the DAC, and other measurements. Results on selected materials, with a view to illustrating the physics behind high-pressure phenomena, are presented and discussed. These include metal-semiconductor transitions, electronic transitions, phonons and high-pressure lattice dynamics, and phase transitions. A whole section is devoted to the behavior of condensed gases, principally ${\mathrm{H}}_2$, ${\mathrm{D}}_2$, ${\mathrm{O}}_2$, ${\mathrm{N}}_2$, and rare-gas solids. The concluding section briefly deals with speculations on ultra-high-pressure research with the DAC in the future.