Stony Brook University Geosciences Researchers Re-Establish the Structure of Magnesium Borohydride
An international team led by Xiang-Feng Zhou and Artem R. Oganov, PhD, theoretical crystallographers in the Department of Geosciences and Department of Physics and Astronomy at Stony Brook University, have established the structure of one of the most important high-energy-density materials, magnesium borohydride or Mg(BH4)2. Their findings, “First-Principles Determination of the Structure of Magnesium Borohydride,” have been published in the December 13 edition of Physical Review Letters.
“Experimental crystal structure determination is often viewed as a routine task with a guaranteed correct result, but we successfully challenged the ‘experimental’ structure of ä-Mg(BH4)2 ,” said Zhou. “This material contains nearly 15 wt. % hydrogen, which makes this an important energy material,” added Oganov.
Structures of several modifications of Mg(BH4)2 were known from high-quality powder diffraction data, a rather standard method for determining crystal structures of materials. Researchers used Prof. Oganov’s breakthrough evolutionary method for crystal structure prediction, aiming to find the most stable structures of Mg(BH4)2 at different conditions.
To Zhou’s surprise, among the theoretically predicted structures he did not find the structure earlier proposed by experimentalists for the ä-phase. He then investigated the experimental structural model and found it to be very unfavorable compared to the theoretically predicted models. Even worse, the “experimental” structure was found to be unable to sustain its own lattice vibrations - predicted to fall apart as a result of atomic thermal motion. This indicates that the “experimental” structure is absolutely impossible – even as a metastable state.
Comparing the diffraction patterns of the theoretically predicted structure with experiments, Zhou realized that there is a perfect match. Subsequently, he found yet another structure that matches experimental data. Thus, there are at least three completely different crystal structures that match experimental diffraction data, but one of them – the one claimed by experimentalists – has been ruled out. The other two structures were shown to explain another mystery - the existence of two almost indistinguishable phases called ä and ä’ (previous experiments were unable to propose any solution for the latter). Zhou and colleagues determined the structures of these phases to have symmetries I41/acd and P-4.
“It is indeed surprising that experimental work, based on high quality data, failed to correctly solve these simple and highly symmetric crystal structures, containing only six non-hydrogen atoms,” said Zhou. “We were also surprised to see completely different structures having identical diffraction patterns. In such situations, which may be more common than we expect, theoretical structure searching will play a major role.”
“Crystal structure is the basis for understanding the behavior of materials,” said Oganov. “The possibility to predict crystal structures is a major breakthrough of our time and will prove crucial for the future discovery of new materials.”
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...
HZI researchers pave the way for new agents that render hospital pathogens mute
Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...
Scientists from the MPI for Chemical Energy Conversion report in the first issue of the new journal JOULE.
Cell Press has just released the first issue of Joule, a new journal dedicated to sustainable energy research. In this issue James Birrell, Olaf Rüdiger,...