Researching solids under pressure is important for many applications. Exploring minerals under increasing pressure can give insight to processes which took place during the formation of the earth or uncover transformations to other phases that prevent the continuation of seismic waves during earthquakes. Industrially relevant materials like steels or concretes are in some applications subjected to high amounts of pressure and possible phase transitions to a brittle form need to be investigated beforehand. Moreover, high pressure phases can withhold desired physical properties that can only be discovered with a suitable measurement setup.
Diamond Anvil Cells (DAC) are built as two diamond crystals, separated by a gasket ring and encapsulated by a metallic housing to distribute the pressure and prevent misalignment of the diamonds. The cavity of the gasket is filled with a, usually liquid, pressure transmitting medium, the sample itself and oftentimes a small chip of ruby. This small ruby chip is used as an internal pressure standard. Diamond is one of the hardest materials known to man and, due to its cubic space group symmetry, produces only a limited number of diffraction spots. Thus, the primary and diffracted beams can pass through the anvils with minimal attenuation or deviation. Moreover, when using a laser heating set up it is possible to combine high pressure and high temperature research into one experiment.
The dedicated, computer controlled, sample stage for round 55 mm diameter DACs, developed by STOE, allows to precisely align the crystal with the pressure cell in the primary beam. Additionally, our X-AREA software features a program package for DAC experiments, which facilitates excluding diamond reflections from the data set, optimizes runs for the small opening angle of a DAC, offers a special shading mask and much more.