Ammonia is one of the most abundant substances in our solar system. In many state-of-the-art laboratories it is possible to produce very intense electric fields that allow to investigate various phenomena by means of diverse chemical-physical techniques. However, the effects produced by electric fields on liquid ammonia have never been studied until now. In a study published on The Journal of Physical Chemistry Letters, a research group of the Institute for physical-chemical processes of the National research council (Cnr-Ipcf) of Messina, in collaboration with the Czech Academy of Sciences based in Brno, using cutting-edge supercomputing simulation methods, have demonstrated for the first time that intense electric fields are capable of inducing a structural transition from the liquid state to a new solid phase of ammonia.
Electrofreezing (i.e., the crystallization of a substance induced by electric fields) is known to be relevant in many natural processes, ranging from tropospheric dynamics to food chemistry. Although electrofreezing is a phenomenon studied more than a century ago, until now there is no evidence to support its realization. From a fundamental point of view, the study demonstrates that, just like extreme regimes of temperature and pressure, also intense electric fields can be used as a key tool to access previously unexplored regions in the phase diagrams of matter.
“This finding has relevance in the field of planetary sciences, identifying the possibility that unknown solid ammonia structures can be found in planetary conditions where intense electric fields are ubiquituous, especially in the vicinity of minerals that forms the interior of ice giants and rocky planets”, claims Giuseppe Cassone researcher at Cnr-Ipcf and corresponding author of the scientific publication. “In addition, the possibility of creating solid phases of ammonia through the application of electric fields paves the way toward the development of safe storage and transport strategies for the production of hydrogen (H2), of which ammonia is a precursor”.
Liquid hydrogen must be stored under much more cryogenic conditions than ammonia, which is therefore less energy-intensive. Nevertheless, ammonia in the liquid phase is dangerous to handle and transport: “Having demonstrated the possibility of keeping this substance solid at temperatures and pressures at which it normally occurs in the liquid state therefore opens up novel scenarios that can accelerate the extensive usage of ammonia as a precursor of hydrogen”, concludes Franz Saija, researcher at Cnr-Ipcf and co-author of the article.