Room temperature

DEFYING THE ACHILLES HEEL OF ‘WONDER MATERIAL’ GRAPHENE: RESILIENCE TO EXTREME CONDITIONS

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Researchers from the University of Exeter have discovered that GraphExeter – a material adapted from the ‘wonder material’ graphene – can withstand prolonged exposure to both high temperature and humidity.

The research showed that the material could withstand relative humidy of up to 100 per cent at room temperature for 25 days, as well as temperatures of up to 150C – or as high as 620C in vacuum.

The previously unknown durability to extreme conditions position GraphExeter as a viable and attractive replacement to indium tin oxide (ITO), the main conductive material currently used in electronics, such as ‘smart’ mirrors or windows, or even solar panels. The research also suggests that GraphExeter could extend the lifetime of displays such as TV screens located in highly humid environments, including kitchens.

These research findings are published in the respected scientific journal, Scientific Reports, on Thursday, 8 January 2015.

Lead researcher, University of Exeter engineer Dr Monica Craciun said: “This is an exciting development in our journey to help GraphExeter revolutionise the electronics industry.

“By demonstrating its stability to being exposed to both high temperatures and humidity, we have shown that it is a practical and realistic alternative to ITO. This is particularly exciting for the solar panel industry, where the ability to withstand all weathers is crucial.”

Dr Saverio Russo, also from the University of Exeter, added: “The superior stability of GraphExeter as compared to graphene was unexpected since the molecules used to make GraphExeter (that is FeCl3) simply melt in air at room temperature.

“Having a metallic conductor stable at temperatures above 600C, that is also optically transparent and flexible, can truly enable novel technologies for space applications and harsh environments such as nuclear power centrals.”

At just one atom thick, graphene is the thinnest substance capable of conducting electricity. It is very flexible and is one of the strongest known materials. The race has been on for scientists and engineers to adapt graphene for flexible electronics. This has been a challenge because of its sheet resistance, which limits its conductivity.

Three-dimensional carbon goes metallic.

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A theoretical, three-dimensional (3D) form of carbon that is metallic under ambient temperature and pressure has been discovered by an international research team.

The findings, which may significantly advance carbon science, are published online this week in the Early Edition of the Proceedings of the National Academy of Sciences.

3-dimensional carbon goes metallic

Carbon science is a field of intense research. Not only does carbon form the chemical basis of life, but it has rich chemistry and physics, making it a target of interest to material scientists. From graphite to diamond to Buckminster fullerenes, nanotubes and graphene, carbon can display in a range of structures.

But the search for a stable three-dimensional form of carbon that is metallic under , including temperature and pressure, has remained an ongoing challenge for scientists in the field.

Researchers from Peking University, Virginia Commonwealth University and Shanghai Institute of Technical Physics employed state-of-the-art theoretical methods to show that it is possible to manipulate carbon to form a three-dimensional metallic phase with interlocking hexagons.

“The interlocking of hexagons provides two unique features – hexagonal arrangement introduces metallic character, and the interlocking form with tetrahedral bonding guarantees stability,” said co-lead investigator Puru Jena, Ph.D., distinguished professor of physics in the VCU College of Humanities and Sciences.

The right combination of these properties could one day be applied to a variety of technologies.

“Unlike high-pressure techniques that require three terapascals of pressure to make carbon metallic, the studied structures are stable at ambient conditions and may be synthesized using benzene or polyacenes molecules,” said co-lead investigator Qian Wang, Ph.D., who holds a professor position at Peking University and an adjunct faculty position at VCU.

“The new metallic  structures may have important applications in lightweight metals for space applications, catalysis and in devices showing negative differential resistance or superconductivity,” Wang said.

According to Jena, the team is still early in its discovery process, but hope that these findings may move the work from theory to the experimental phase.

The study is titled, “Three-dimensional Metallic Carbon: Stable Phases with Interlocking Hexagons.”