In our daily life, pressure plays an important role; from the weather to traveling by for example car or plane. Also during chemical reactions pressure is an essential part. Chemical reactions such as transitions between solids, liquids and gases or phase transitions within the same state can be accelerated by changing pressure. In the laboratory, the pressure can be manipulated on small scale in order to for example reproduce the pressure close to the core in the earth. Small scale scenarios can help researchers to gain information about how the nature behaves. Furthermore, when applying pressure on a single crystal new phase transitions can be forced to happen to decrease the total energy in the system. When the new structure is solved, new knowledge about things such as bonding lengths, energies and interatomic distances Moreover, by researching how compounds react at different pressures, researchers can discover and develop new kind of materials that can solve new or existing challenges.
At Aarhus University we have built a comprehensive suite of techniques for high pressure solid state chemistry, including a state-of-the-art large volume multi-anvil press, which is capable of generating pressures up to 250,000 bar (25 GPa) and temperatures up to 2000 K and a number of different diamond anvil cells (DACs). The extreme conditions provide exceptional possibilities to manipulate matter into new forms. It is common knowledge that diamond is a phase of carbon generated at very high pressure. Fewer probably consider that other new materials can also be made in the same fashion; by using pressure as the driving force. In many cases, these novel materials can be recovered to ambient conditions as stable or meta-stable compounds.
The diamond anvil cell (DAC) is the go to device when it comes to exploring solids under pressure. High pressure synthesis studies coupled with high pressure crystallographic investigations using DACs provide an exceptional possibility to obtain crystallographic information under high pressure.
We have on-going projects looking into perovskites, pyrochlores, novel pentavalent post-perovskites, rare-earth nitrides and bismuth chalchogenide topological insulators. Our section also have modern facilities for measurement of physical properties, elemental analysis and the handling of oxygen and water sensitive samples produced at high pressure.