Named beryllonitrene, the new two-dimensional (2D) material consists of regularly arranged nitrogen (N) and beryllium (Be) atoms and has an unusual electronic lattice structure, according to a study led by the University of Bayreuth.
The hexagonal electronic lattice (green) of beryllonitrene conforms to its crystal structure, and looks like a slightly distorted honeycomb; the beryllium atoms are shown as gray balls, nitrogen atoms as blue balls. Image credit: M. Bykov.
“For the first time, close international cooperation in high-pressure research has now succeeded in producing a chemical compound in that was previously completely unknown,” said Professor Natalia Dubrovinskaia, a researcher in the Laboratory for Crystallography at the University of Bayreuth.
“This compound could serve as a precursor for a 2D material with unique electronic properties.”
Using laser-heated diamond anvil cells, Professor Dubrovinskaia and colleagues studied high-pressure high-temperature chemical reactions in the nitrogen-beryllium system.
Their experiments led to a synthesis of several layered beryllium polynitrides.
In particular, at 84 GPa and 2,000 K, laser-heating of beryllium and nitrogen resulted in the synthesis of a compound with the chemical composition BeN4 and a triclinic structure.
Upon decompression to ambient conditions, it transforms into a compound with atomic-thick BeN4 layers interconnected via weak van der Waals bonds and consisting of polyacetylene-like nitrogen chains.
“Van der Waals bonds between its layers and presence of anisotropic Dirac cones in its electronic structure show that 2D BeN4, beryllonitrene, has unique properties,” they said.
“Indeed, the high degree of electron-hole symmetry makes the 2D BeN4 system similar, in some respect, to the world of high-energy particles with its symmetry between particles and antiparticles.”
According to the team, beryllonitrene represents a qualitatively new class of 2D materials that can be built of a metal atom and polymeric nitrogen chains.
“There is no possibility of devising a process for the production of beryllonitrene on an industrial scale as long as extremely high pressures, such as can only be generated in the research laboratory, are required for this,” said Professor Leonid Dubrovinsky, a researcher in the Bavarian Research Institute of Experimental Geochemistry & Geophysics at the University of Bayreuth.
“Nevertheless, it is highly significant that the new compound was created during decompression and that it can exist under ambient conditions.”
“In principle, we cannot rule out that one day it will be possible to reproduce beryllonitrene or a similar 2D material with technically less complex processes and use it industrially.”
“With our study, we have opened up new prospects for high-pressure research in the development of technologically promising 2D materials that may surpass graphene.”
The findings were published in the journal Physical Review Letters.
Maxim Bykov et al. 2021. High-Pressure Synthesis of Dirac Materials: Layered van der Waals Bonded BeN4 Polymorph. Phys. Rev. Lett 126 (17): 175501; doi: 10.1103/PhysRevLett.126.175501