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Coal-based electronics: A potential usurper to silicon’s throne?

by • April 20, 2016 • No Comments

Graphene may be the poster child of thin movie electronics, and silicon the current king of materials for semiconductors, but if scientists of MIT get their way, graphene’s humble cousin, coal, may soon be giving them both a run for their money. For the firstly time, electronic devices have been made of thin movies of coal and the research points to a range of uses which this bargain-priced and abundant material may have in electronic devices, solar panels, and batteries.

Coal comes in four various types, all characterized by their composition, age, and the degree of compression applied to them over the millennia. Specifically, they range of lignite, a soft brown combustible sedimentary rock created of naturally compressed peat, through to sub-bituminous, bituminous and lastly to anthracite, a compacted variety with a high carbon content and fewer impurities than the other types. In developing their application, the MIT researchers analyzed the chemical, electrical, and optical properties of thin movies of all four various types of coal, and decided on anthracite as the most suitable for the devices created in their experiments.

To prepare the coal for the research, the scientists created a system to crush the anthracite to a powder, suspend it in solution, and deposit it in thin uniform movies on a substrate, much like to the way it is done in fabricating other electronic devices of graphene or silicon. But, unlike silicon which must be refined to a purity of over 99 percent, coal can only be used in its crushed form without additional refining.

Despite coal being one of the most abundant substances used by humans, the vast bulk of it has only been used as a fuel for burning, with almost all of its electrical and optical properties rarely studied for use in electronic devices.

“The material has never been approached this way preceding, to find out what the properties are, what one-of-a-kind showcases there can be.” said MIT doctoral student Brent Keller.

As an first proof of concept for what the team sees as a wide range of possible uses, the researchers created an electrical heating device which may see duty in anything of being part of a part of a biomedical implant, to helping defrost car windows or aircraft wings. Along with the properties of this device, the researchers in addition discovered which by altering the temperature used to system the coal, a sizeable range of the optical and electrical properties of the material may be precisely tailored to meet specified values.

But actually this new discovered capability for coal is only the beginning of its future, according to the researchers. Given which the four main varieties of coal selected have most other subsets all with differing compositions, the team believes which there may as yet be strikingly useful differences which may be exploited in other kinds of electronic devices.

“When you appear at coal as a material, and not only as a thing to burn, the chemistry is amazingly rich,” said Professor Jeffrey Grossman, of the Department of Materials Science and Engineering at MIT.

According to Professor Grossman, the leading advantage of the new material is its low cost to create of an amazingly bargain-priced base material, allied with an uncomplicated solution procedure which allows for exceptionally low fabrication costs. Compared to silicon or graphene for use in electronic semiconductors, coal thin movie is far and away the simplest to create for the reason it will not need such high levels of purification.

Silicon and graphene may in addition be relatively abundant, but the purified form of silicon, for example, is vastly additional expensive than coal by comparison. It is in addition easily and readily tunable across conductive and resistive paths, and is quite robust in nature with a naturally high thermal stability.

“[A] quite extensive and interesting study to facilitate the belief of unrefined coal’s future for practical significance.” said Shenqiang Ren, an associate professor of mechanical engineering at Temple University who was not involved in this research, but studied the results. “This is a worthwhile step (probably the firstly) to use nanocarbon materials, directly of unrefined coal, with controllable electronic properties and great stability and scalability.”

The results of this research were published in the journal Nano Letters.

Source: MIT

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