Q-carbon

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Q-carbon is a carbon allotrope, discovered in 2015, which is ferromagnetic, electrically conductive, and glowing when exposed to low energy levels. It's relatively cheap to make, and some news reports claim that it has replaced diamonds as the toughest substances in the world. In 2018, only the inventors themselves reported successfully creating Q-carbon.

According to the researchers, Q-carbon shows a random amorphous structure that is a mixture of 3-way (sp ² ) and 4-way (sp ³ ) bonds, rather than a uniform ³ found on diamonds. The carbon is melted using a nanosecond laser pulse, then quickly extinguished to form Q-carbon, or a mixture of Q-carbon and diamond. Q-carbon can be made to take some shape, from nanoneedle to large diamond film. Researchers can also create nitrogen-void (NV) nanodiamonds and arrange them for a variety of potential applications, ranging from nanosensing and quantum computing to biomarkers.

Video Q-carbon

Discovery

The discovery of Q-carbon was announced in 2015 by a research group led by Jagdish Narayan, a professor of materials science and engineering at North Carolina State University, and graduate student Anagh Bhaumik. Combined with the invention of Q-boron nitride (Q-BN), and converting carbon to diamond and h-BN into c-BN at room temperature and air pressure, it is a major breakthrough in diamond science and technology and related materials.

This process begins with Narayan's paper on laser annealing, published in Science, and culminates in 2015-16 with another series of papers and three US patent applications: 62/245,108 (2015); 62/202,202 (2015); and 62/331,217 (2016). It has been licensed by Q-Carbon, LLC to commercialize products based on Q-carbon, diamond, Q-BN and c-BN.

Maps Q-carbon

Production

Typically, diamonds are formed by heating the carbon at very high temperatures (& gt; 5,000 K) and pressure (& gt; 120,000 atmospheres). However, Narayan and his group used kinetics and control the pulsed laser nanosecond liquefaction time to overcome the thermodynamic limitations and create a super cold state that allows the conversion of carbon into Q-carbon and diamonds at ambient temperature and pressure. This process uses a high-power laser pulse, similar to that used in eye surgery, which lasts about 200 nanoseconds. This increases the carbon temperature to about 4,000 K (3,700 Â ° C; 6,700 Â ° F) at atmospheric pressure. The resulting liquid is then quenched (cooled rapidly); this stage is the source of "Q" in the name of the material. Supercooling levels below the melting temperature determine the new phase of carbon, whether Q-carbon or diamond. The high rate of cooling produces Q-carbon, whereas diamonds tend to form when the free energy of the carbon liquid is equal to the diamond.

Using this technique, diamonds can be doped with n-and p-type dopants, which are essential for high-power solid-state electronics. During the rapid crystal growth of the melts, dopant concentrations can extend far beyond the thermodynamic solubility limit through the phenomenon of the solute trap. This is necessary to achieve a fairly high concentration of free carriers, since these dopants tend to be deep donors with high ionisation energies.

It took researchers only 15 minutes to make one carat Q-carbon. Initial studies created Q-carbon from a sapphire thin plate coated with amorphous (non-crystalline) carbon. Further research has shown that other substrates, such as glass or polymer, also work. This work was then extended to turn h-BN into a pure-c-BN phase.

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Properties

Q-carbon is non-crystalline, and while it has a mixture of sp ² and sp ³ bonds, most sp ³ , which leads to its hardness a unique and its electrical, optical and magnetic properties. Q-carbon is harder than diamonds of 10-20% because carbon is a metal in a liquid state and becomes very dense, with a bond length smaller than a diamond. Unlike all other known carbon forms, Q-carbon is ferromagnetic, with a saturation magnetization of 20 emu/g and an estimated Curie temperature of about 500 K.

Depending on the cooling rate of the super cold country, Q-carbon can be a semiconductor or metal. This light is more radiant than diamond when exposed even to low levels of energetic radiation due to its stronger negative electron affinity.

Boron-doped Q-Carbon shows BCS-type superconductivity up to 57K.

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See also

• Carbon Allotropes

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References

Source of the article : Wikipedia