Scientists generate compounds with diamond-like hardness

Scientists subjected substances containing carbon and nitrogen to extreme heat and pressure to yield a material that they said could rival diamond in its hardness.

The international team of scientists led by the University of Edinburgh, UK, exposed these carbon nitrogen mixtures to pressures about a million times the atmospheric – between 70 and 135 gigapascals – and temperatures of more than one and a half thousand degrees Celsius.

The resulting materials, called carbon nitrides, were found to be tougher than cubic boron nitride, the second hardest material after diamond. The findings are published in the journal Advanced Materials.

The researchers said that these nitrides, with “necessary building blocks for super-hardness”, have potential industrial applications such as protective coatings for cars and spaceships, high-endurance cutting tools, solar panels and photodetectors.

The team also observed that these nitride compounds retained their diamond-like qualities when they returned to ambient pressure and temperature conditions.

They said that further calculations and experiments suggested that these new materials possessed additional properties including photoluminescence, or glowing by absorbing light, and high energy density, where a large amount of energy can be stored in a small amount of mass.

The researchers positioned these extremely hard nitrides as “ultimate engineering materials to rival diamonds”.

The exceptional properties of carbon nitrides were first noticed in the 1980s, including high resistance to heat.

However, despite multiple attempts to unlock their potential and generate them, no credible results were reported, according to the researchers.

“Upon the discovery of the first of these new carbon nitride materials, we were incredulous to have produced materials researchers have been dreaming of for the last three decades.

“These materials provide strong incentive to bridge the gap between high pressure materials synthesis and industrial applications,” said the study’s corresponding author Dominique Laniel from the University of Edinburgh.

Along with being multi-functional, these materials can be rendered technologically relevant through synthesis pressures similar to those found thousands of kilometres in the Earth’s interior, according to study author Florian Trybel from the University of Linkoping, Sweden.

“We strongly believe this collaborative research will open up new possibilities for the field,” said Trybel.