Pentadiamond - A Material As Hard As Diamond But As Light As Graphite

Mayukh Bari13 July 2020 9:06PM IST
2 min read288

Yasumaru Fujii and colleagues at the University of Tsukuba, Japan created a new material using quantum-mechanical simulations. This could be a potentially useful material for its interesting properties. The results show that novel, stable carbon allotropes could be custom designed with properties suited to specific applications. They named it 'Pentadiamond'.

Carbon is an extremely versatile element: it has hundreds of hypothetical forms and several observed varieties, including diamond and graphite. In diamond, every carbon atom connects to four others in a 3D cubic lattice that is strong and hard. But in graphite, each atom bonds only to three others, forming flat sheets of hexagons.

The team simulated the assembly of a covalent 3D network from a mixture of two hydrocarbon molecules, both containing pentagonal carbon rings. Calculations of the network's total energy and electronic structure confirmed its stability and revealed it to be an indirect semiconductor. Their model also indicated that the material has some notable mechanical properties.

  • First, it is nearly as hard as diamond yet is much less dense.
  • Second, it has a negative Poisson's ratio, meaning it becomes thicker when stretched.
  • The researchers attribute the hardness to the combination of electronic configurations present in the structure: while some atoms bind to produce one geometry, others reinforce the network like cross braces in a building. The material's unusual behavior under strain, meanwhile, could be due to its pentagonal components.

    The researchers say that pentadiamond and other novel materials could be created easily using conventional copolymer synthesis methods, and they could be useful as reinforcement materials in technologies such as gas storage, chemical engineering, and optoelectronics.