Graphene has been in the news lately. Given that graphene has superior electrical mobility compared to silicon and is some 200 times stronger than steel, it is understandable that there is an interest. Recently, researchers at UC Riverside [1] have developed a means of creating magnetism in graphene while keeping its electrical properties. The key to the process was to use a laser molecular beam epitaxy to grow a mono-layer of graphene on an insulating sheet of yttrium iron garnet (YIG). The resulting graphene incorporated impurities of the YIG into its structure to create the magnetic effect without disrupting the electrical properties of the graphene. Applications yet to be determined, but a new “spin” on graphene.
One issue with graphene is that the majority of processes require multiple steps at very high temperatures. Caltech researchers have developed a process where they grow electronic grade graphene using lower temperatures in a shorter time. [2] They claim that this process will produce larger size amounts of graphene (in the centime ranges) than the conventional high temperature techniques, which produce graphene in the millimeter range. As with a lot of scientific breakthroughs, a couple of fortunate “accidents” created the larger size graphene. Investigating the produced material resulted in a better understanding of the process and led to the ability to also create “custom” graphene with “different” properties.
Researchers at Rice University have found that the symmetry of the structure on which graphene is grown has a critical impact on its resultant shape. The edges of the graphene are important to its resultant electrical properties, which affects its usefulness. [3] The atoms for a specific arrangement that is a function of the underlying structure. Materials that are formed on one type of grain structure will have the same shape. The researchers indicated that the differences can be envisioned a cutting a cube in different was. It is possible to end up with a square, a rectangle, or even a triangle.
An issue with graphene in the current manufactured form is that there are small imperfections in the lattice. This condition inhibits the usage of large-scale graphene. However, researchers at Northwestern, the University of Minnesota, and Penn State have shown the possibility of using the imperfections in graphene as a means of improved water filters and fuel cells. [4] Their theoretical modeling shows improved flow through the lattice areas that have the missing carbon atoms.
Researcher continue to explore other material and other applications. Researchers at the University of Minnesota are working on Black phosphorous. [5] They have shown that phosphorous that is 20 atoms thick has improvements in efficiencies over graphene. Depending on the number of atomic layers, the material can be tuned to different optical wavelengths. The potential for optical computing and optical interconnects is significant.
It is important to remember that all of these developments at the atomic scale began in earnest with the discovery of the buckeyball (C60). As researchers have learned how to develop materials in the nanometer region, it should not be surprising that other applications are being developed. Sub-micron carbon spheres have been produced. The possibility of this material being employed as an oil additive to reduce engine friction should not come as a surprise. Research is opening new doors for application that were impossible only a few years ago.
References:
[3] http://semiengineering.com/system-bits-march-17/ & http://www.rdmag.com/news/2015/03/symmetry-matters-graphene-growth?et_cid=4466707&et_rid=658352741&type=cta
