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CNR: Alamanacco della Scienza


N. 15 - 30 ott 2013
ISSN 2037-4801

International info   a cura di Cecilia Migali


New material almost hard as diamond

Scientists have for the first time synthesised a new superconducting material designed using computer simulations. Studies with X-rays proved that its atomic structure corresponds to the theoretical prediction. The hitherto unknown material, iron tetraboride FeB4 does not occur in nature, and in addition to the predicted properties, it is also nearly as hard as diamond. The results were published in 'Physical Review Letters'.

The team of scientists was led by Natalia Dubrovinskaia and Leonid Dubrovinsky from the University of Bayreuth (Germany) and also comprised scientists from Max Planck Institute for Chemical Physics of Solids, Dresden, and Technische Hochschule Wildau, Wildau (Germany); National Institute of Chemical Physics and Biophysics, Tallinn (Estonia); Università degli Studi di Milano, Milano (Italy); University of Antwerp, Antwerp (Belgium); Binghamton University, Vestal (Usa), and the European Synchrotron Esrf in Grenoble (France). Superconductors conduct electric current with no resistance when cooled below a certain critical temperature. They have many applications where strong magnetic fields are needed, for example in hospital scanners and particle accelerators. Although the superconductivity was discovered more than 100 years ago, synthesis of new superconductors based on theoretical forecast has so far remained elusive.

Computational design of superconductors is challenging because only 'conventional' superconductors are understood well enough by theory with predictive power. Determining the critical temperature below which the material becomes superconducting also needs a lot of computing power. Second, the materials' stability and superconductivity tend to be inversely correlated so that many proposed superconducting materials are not stable enough to exist and those that do form are poor superconductors. In 2010, a team of scientists predicted iron tetraboride (FeB4) to be a superconductor. This new material is made out iron and boron, two cheap elements, and it should exhibit a brand-new crystal structure. The synthesis of the iron tetraboride was a particular research success of Huiyang Gou who devoted himself to this challenge as a postdoctoral Humboldt Research Fellow at the University of Bayreuth. The iron tetraboride, which does not occur in nature, was produced by compressing the ingredients to pressures above 80.000 bar and high temperatures of 1500 °C. “Here at the University of Bayreuth, we have at our disposal unique instruments for synthesizing materials under extreme conditions of pressure and temperature”, says Huiyang.

Per saperne di più: - www.esrf.eu/home/news/general/content-news/general/x-rays-reveal-the-first-designer-superconductor.html