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Global scientific team uncovers crystal structure of sodium boride

Its properties have been the issue of debate for a long time

MOSCOW, March 29. /TASS/. An international research team with the participation of Professor of Skolkovo Institute of Science and Technology (Skoltech) and Moscow Institute of Physics and Technology (MIPTArtem Oganov defined the crystal structure and chemical composition of sodium boride, with its properties being the issue of debate for a long time, Skoltech’s press office reported.

Boron is a chemical element that builds complex ultra-hard crystal modifications. The compounds of boron and metals - borides - often possess complex chemical compositions and crystal structures. Using the USPEX code developed by Professor Oganov, which is a computer prediction of a crystal structure, the scientists managed to settle the ‘Na2B30 or Na2B29’ dispute on the composition of sodium boride.

A real mystery

"This work was a mystery. It turned out that everyone in some way was mistaken. Some made mistakes in the chemical formula, others in the structure. For me, it is always surprising in such cases that although we often talk about living in the 21st century and possess super-devices enabling us to do nearly everything, despite the really tremendous progress in science, we often don’t even know which substance we typically hold in our hands," Oganov explained.

The results of the new scientific study were published in the journal Physical Review B .

According to the researcher, the sodium boride is "a substance which is notably softer than a diamond and is at the lower end of the super-hardness range." "In contrast to diamonds, the synthesis of sodium boride does not require pressure and is therefore much cheaper," Oganov added.

He also noticed that during the course of the research it turned out that Na2B30 is stable while Na2B29 is not. It has been shown that the addition of a single atom dramatically changes not only the stability but also the electronic properties by transforming the substance from a metal into a semiconductor and boosting the hardness of the material.

"The crystal structure of Na2B30 discovered in our work is more stable than those suggested by previous researchers, but similarly it is also dovetails well with experimental diffraction data," Oganov said.

According to Oganov, in the future, sodium boride can be applied in any field where very hard elements are required, for example, for creating drilling devices or other technical equipment.