Researchers at the University of Bayreuth, together with partners in China and the USA, have produced an oxide glass with unprecedented toughness. Under high pressures and temperatures, they succeeded in paracrystallizing an aluminosilicate glass: The resulting crystal-like structures cause the glass to withstand very high stresses and are retained under ambient conditions. Paracrystallization thus proves to be a promising process for producing extremely break-resistant glasses. In "Nature Materials", the researchers present their findings, in which the German Electron Synchrotron (DESY) in Hamburg also participated.
In many respects, glass is an attractive material for modern technologies. However, its brittleness, which easily leads to cracks and fractures, limits its potential applications. Research approaches to highly increase the toughness of glass while retaining its advantageous properties have largely failed to produce the desired results.
The new approach presented in "Nature Materials" starts with oxide glasses which have a rather disordered internal structure and are the most widely commercially utilized glass materials. Using aluminosilicate, which contains silicon, aluminum, boron and oxygen, as an example, the research team in Germany and China has now succeeded in giving it a new structure. To this end, they employed high-pressure and high-temperature technologies at the Bavarian Research Institute of Experimental Geochemistry and Geophysics (BGI) of the University of Bayreuth.
At pressures between 10 and 15 gigapascals and a temperature of around 1,000 degrees Celsius, the silicon, aluminum, boron and oxygen atoms grouped together to form crystal-like structures. These structures are called "paracrystalline" because they differ significantly from a completely irregular structure, but they do not approach the clear regular structure of crystals. Both empirical analyses using spectroscopic techniques and theoretical calculations clearly showed this intermediate state between crystal structures and amorphous irregularity.