Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

Stony Brook University Geosciences Researchers Re-Establish the Structure of Magnesium Borohydride

17.12.2012
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.”

| Newswise
Further information:
http://www.stonybrook.edu

More articles from Physics and Astronomy:

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

nachricht Magnetic moment of a single antiproton determined with greatest precision ever
19.01.2017 | Johannes Gutenberg-Universität Mainz

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Verkehrsstau im Nichts

Konstanzer Physiker verbuchen neue Erfolge bei der Vermessung des Quanten-Vakuums

An der Universität Konstanz ist ein weiterer bedeutender Schritt hin zu einem völlig neuen experimentellen Zugang zur Quantenphysik gelungen. Das Team um Prof....

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: Textiler Hochwasserschutz erhöht Sicherheit

Wissenschaftler der TU Chemnitz präsentieren im Februar und März 2017 ein neues temporäres System zum Schutz gegen Hochwasser auf Baumessen in Chemnitz und Dresden

Auch die jüngsten Hochwasserereignisse zeigen, dass vielerorts das natürliche Rückhaltepotential von Uferbereichen schnell erschöpft ist und angrenzende...

Im Focus: Wie Darmbakterien krank machen

HZI-Forscher entschlüsseln Infektionsmechanismen von Yersinien und Immunantworten des Wirts

Yersinien verursachen schwere Darminfektionen. Um ihre Infektionsmechanismen besser zu verstehen, werden Studien mit dem Modellorganismus Yersinia...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Nachhaltige Wassernutzung in der Landwirtschaft Osteuropas und Zentralasiens

19.01.2017 | Veranstaltungen

Künftige Rohstoffexperten aus aller Welt in Freiberg zur Winterschule

18.01.2017 | Veranstaltungen

Bundesweiter Astronomietag am 25. März 2017

17.01.2017 | Veranstaltungen

 
VideoLinks
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Flashmob der Moleküle

19.01.2017 | Physik Astronomie

Tollwutviren zeigen Verschaltungen im gläsernen Gehirn

19.01.2017 | Medizin Gesundheit

Fraunhofer-Institute entwickeln zerstörungsfreie Qualitätsprüfung für Hybridgussbauteile

19.01.2017 | Verfahrenstechnologie