Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

Theory of crystal formation complete again

20.02.2013
Exactly how a crystal forms from solution is a problem that has occupied scientists for decades.

Researchers at Eindhoven University of Technology (TU/e), together with researchers from Germany and the USA, are now presenting the missing piece. This classical theory of crystal formation, which occurs widely in nature and in the chemical industry, was under fire for some years, but is saved now.

The team made this breakthrough by detailed study of the crystallization of the mineral calcium phosphate –the major component of our bones. The team published their findings yesterday in the online journal Nature Communications.

Crystallization is the formation of a solid ordered substance, such as happens when water freezes. In nature, crystals are mostly formed from ions which are dissolved in water, as for example in the formation of shells or bone. This involves the clustering of ions into increasingly large nuclei, until a crystal is formed when a certain size is reached. However, the details of this growth process have been the subject of discussion for many years.

According to the existing theories, it is individual ions that group together to form crystal nuclei. But in 2009 chemists led by dr. Nico Sommerdijk (TU/e) showed the presence of an intermediate step in the growth process of calcium carbonate crystals. The ions were thought to first form small clusters, which then grow into crystal nuclei. This finding, which was the cover story of Science, caused controversy because it appeared to contradict the classical crystallization theories which did not allow for such an intermediate step.

Now Sommerdijk is having second thoughts about his 2009 conclusions. At least, the answer now turns out to be more subtle than was thought at that time. Together with researchers from the Max Planck Institute in Germany and the Lawrence Berkeley National Laboratory in the USA, he looked more closely at the role of these so-called pre-nucleation clusters in the growth process of the mineral calcium phosphate. Using a cryo-electron microscope, which makes images of deep-frozen samples, he was able to identify the precise components of the clusters and study the growth process in detail.

In their article in Nature Communications Sommerdijk concludes that the clusters do not form a clearly defined intermediate step, but instead are part of a gradual growth process. Sommerdijk refers to the formation of clusters as a 'false start' by the ions, because the clusters already start to organize themselves step by step while still in solution, without actually forming growth nuclei. This new understanding means the existing theories no longer need to be overturned. Sommerdijk's team now complete the theory by describing alternative 'pathways' along which crystals can form. Sommerdijk's new conclusions have since been confirmed in a second study into crystal formation in the mineral magnetite, which was published online this month in Nature Materials.

In recent years both the role and the composition of the pre-nucleation clusters were the subject of intense scientific discussions, for example last summer during the prestigious Faraday Discussions. There were also disagreements within the team itself about Sommerdijk's new interpretation. Some team members held onto the original scenario, even after numerous new experiments had confirmed that the clusters did not have the same composition and role as believed earlier. Finally it was decided to submit the article, which after four years of experimenting and revision had reached a final length of almost 100 pages, without the names of the team members who were unable to accept the new ideas.

In Sommerdijk's view the most important questions about the formation of crystals have now been answered. This theoretical knowledge is important in many fields, because of the widespread occurrence of crystallization in nature and in the chemical industry. Just a few examples are the formation of coral in the sea, the production of pharmaceuticals and the design of nanoparticles. It could for example help to make production processes less costly, faster or more energy-efficient.

The article 'Ion-association complexes unite classical and non-classical theories for the biomimetic nucleation of calcium phosphate' will be published on 19 February in Nature Communications, DOI 10.1038/ncomms2490.

The article 'Nucleation and growth of magnetite from solution', to which Nico Sommerdijk also contributed, was published online on 3 February in Nature Materials, DOI 10.1038/nmat3558.

Ivo Jongsma | EurekAlert!
Further information:
http://www.tue.nl

More articles from Life Sciences:

nachricht Why some neurons “outsource” their cell body
21.04.2015 | Nationales Bernstein Netzwerk Computational Neuroscience

nachricht Bubbles dilemma solved after more than twenty years
21.04.2015 | University of Twente

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neue Schaltelemente basierend auf elektronischer Selbstorganisation: Orbitronics

Ein internationales Team von Wissenschaftlern aus Dresden, Hamburg, Lausanne und Urbana-Champaign hat, geleitet von einer Gruppe des IFW Dresden, ein neues Konzept für ultra-schnelle elektronische Schaltelemente entwickelt.

Wie die Forscher in der jüngsten Ausgabe von Nature Physics berichten, tritt in dem Material Tantaldisulfid spontan eine bisher unbekannte Texturierung...

Im Focus: On the trail of a trace gas

Max Planck researcher Buhalqem Mamtimin determines how much nitrogen oxide is released into the atmosphere from agriculturally used oases.

In order to make statements about current and future air pollution, scientists use models which simulate the Earth’s atmosphere. A lot of information such as...

Im Focus: Get flexible – get lighter – get smarter – Innovative Materialien für Zukunftsprodukte

Das Fraunhofer-Institut für Silicatforschung ISC aus Würzburg stellt auf der IDTechEx in Berlin vom 28. bis 29. April 2015 neue, multifunktionale Materialien vor, mit denen sich innovative Anwendungen und Produkte realisieren lassen. Arbeitsschwerpunkte sind Barrierematerialien, gedruckte Elektronik, elektrochrome Folien sowie Smart Materials. Sie bedienen die Trends in Industrie und Design zu immer flexibleren, leichteren und intelligenteren Produkten. Das Fraunhofer ISC ist am Stand F17 im Convention Center und Hotel Estrel zu finden.

Präsentiert werden beispielsweise innovative Verkapselungsfolien, die das Fraunhofer ISC zusammen mit dem Fraunhofer IVV entwickelt hat. Die kostengünstig im...

Im Focus: Advances in Molecular Electronics: Lights On – Molecule On

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the University of Konstanz are working on storing and processing information on the level of single molecules to create the smallest possible components that will combine autonomously to form a circuit. As recently reported in the academic journal Advanced Science, the researchers can switch on the current flow through a single molecule for the first time with the help of light.

Dr. Artur Erbe, physicist at the HZDR, is convinced that in the future molecular electronics will open the door for novel and increasingly smaller – while also...

Im Focus: Fortschritt für die molekulare Elektronik: Licht an – Molekül an

Mit einzelnen Molekülen Informationen zu speichern und verarbeiten, um daraus kleinstmögliche Bausteine zu entwickeln, die sich selbstständig zu einem Schaltkreis zusammensetzen – daran arbeiten Wissenschaftler des Helmholtz-Zentrums Dresden-Rossendorf (HZDR) und der Universität Konstanz. Wie sie nun in der Fachzeitschrift „Advanced Science“ berichten, konnten sie erstmalig den Stromfluss durch ein einzelnes Molekül mit Hilfe von Licht einschalten.

Die molekulare Elektronik wird zukünftig ein Fenster hin zu neuartigen und immer noch kleineren und zugleich energieeffizienten Bauelementen oder Sensoren...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

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

Digitale Revolution in der Wissenschaft

21.04.2015 | Veranstaltungen

Zurück zu den Wurzeln – größte nationale Tagung für Nuklearmedizin in Hannover

20.04.2015 | Veranstaltungen

DFG-UNU-Konferenz in New York: Wie kann Wissenschaft zur globalen Nachhaltigkeit beitragen?

20.04.2015 | Veranstaltungen

 
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Warum manche Nervenzellen den Zellkörper „auslagern“

21.04.2015 | Biowissenschaften Chemie

Wie entstehen Metastasen?

21.04.2015 | Biowissenschaften Chemie

Nomadenleben schützt Artenvielfalt - Studie zur Auswirkung des nomadischen Lebens in der Mongolei

21.04.2015 | Studien Analysen