This grahene stuff. Is it stronger by weight than carbon nanotubes? Is it easier to manufacture? Can it be made economically in volume?
I ask, of course, because of that elusive space elevator that requires a lightweight, superstong material to extend from the ground into outer space. I see it playing a dual pupose: as the actual structure for the elevator and as a capacitor for a space-based solar-powered steam generator. I’m imagining big-assed bricks of this stuff ferrying electricity between the power plant and the top end of the elevator "shaft, and then discharging it through the “shaft” and into our homes.
Or is it not really all that cool?
If you take this stuff and roll it up into a thin tube (as you’d presumably be doing, if you want a one-dimensional fiber like an elevator cable), then what you have is a carbon nanotube.
Graphene is considerably easier to make. I was recently quoted $70 for 1/2 lb of graphene. In terms of chemicals, that is dirt cheap. A half gram of nanotubes (I believe single wall) is $250.
Of course if you neatly organize graphene into a structure for building, you have graphite. I don’t know of any structural utility of graphene. It’s main use will be in electronics.
Keeve
July 10, 2009, 4:35am
4
When I read this, I was quite amazed. Not by the $250 per half-gram price. Rather, I didn’t realize that nanotubes were available commercially at any price. And then, just below your post, I saw this ad placed by the local 'bots:
DSeid
July 10, 2009, 4:50am
5
Science June 19 2009
Graphene is a wonder material with many superlatives to its name. It is the thinnest known material in the universe and the strongest ever measured. Its charge carriers exhibit giant intrinsic mobility, have zero effective mass, and can travel for micrometers without scattering at room temperature. Graphene can sustain current densities six orders of magnitude higher than that of copper, shows record thermal conductivity and stiffness, is impermeable to gases, and reconciles such conflicting qualities as brittleness and ductility. Electron transport in graphene is described by a Dirac-like equation, which allows the investigation of relativistic quantum phenomena in a benchtop experiment. This review analyzes recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.
Behind the wall:
The most explored aspect of graphene physics is its electronic properties. Despite being recently reviewed (2–4), this subarea is so important that it necessitates a short update. From the most general perspective, several features make graphene’s electronic properties unique and different from those of any other known condensed matter system. The first and most discussed is, of course, graphene’s electronic spectrum. Electrons propagating through the honeycomb lattice completely lose their effective mass, which results in quasi-particles that are described by a Dirac-like equation rather than the Schrödinger equation (2–4). The latter—so successful for the understanding of quantum properties of other materials—does not work for graphene’s charge carriers with zero rest mass. Figure 2 provides a visual summary of how much our quantum playgrounds have expanded since the experimental discovery of graphene. Second, electron waves in graphene propagate within a layer that is only one atom thick, which makes them accessible and amenable to various scanning probes, as well as sensitive to the proximity of other materials such as high-{kappa} dielectrics, superconductors, ferromagnetics, etc. This feature offers many enticing possibilities in comparison with the conventional 2D electronic systems (2DES). Third, graphene exhibits an astonishing electronic quality. Its electrons can cover submicrometer distances without scattering, even in samples placed on an atomically rough substrate, covered with adsorbates and at room temperature. Fourth, as a result of the massless carriers and little scattering, quantum effects in graphene are robust and can survive even at room temperature. … Graphene is structurally malleable, and its electronic, optical, and phonon properties can be strongly modified by strain and deformation (27). For example, strain allows one to create local gauge fields (3) and even alter graphene’s band structure. Research on bended, folded, and scrolled graphene is also gearing up. … Last year, the first measurements of graphene’s mechanical and thermal properties were reported. It exhibits a breaking strength of ~40 N/m, reaching the theoretical limit (33). Record values for room-temperature thermal conductivity (~5000 W m–1 K–1) (34) and Young’s modulus (~1.0 TPa) (33) were also reported. Graphene can be stretched elastically by as much as 20%, more than any other crystal (27, 33). These observations were partially expected on the basis of previous studies of carbon nanotubes and graphite, which are structurally made of graphene sheets. Somewhat higher values observed in graphene can be attributed to the virtual absence of crystal defects in samples obtained by micromechanical cleavage. Even more intriguing are those findings that have no analogs. For example, unlike any other material, graphene shrinks with increasing T at all values of T because membrane phonons dominate in 2D (35). Also, graphene exhibits simultaneously high pliability (folds and pleats are commonly observed) and brittleness [it fractures like glass at high strains (36)]. The notions constitute an oxymoron, but graphene combines both properties. Equally unprecedented is the observation that the one-atom-thick film is impermeable to gases, including helium (37). When wafers become available, there should be an explosion of interest in (bio)molecular and ion transport through graphene and its membranes with designer pores. … The space between graphene dreams and immediate reality is packed with applications. One such application is neither grand nor mundane: individual ultrahigh-frequency analog transistors (Fig. 4B). This area is currently dominated by GaAs-based devices known as high-electron-mobility transistors (HEMTs), which are widely used in communication technologies. Graphene offers a possibility to extend HEMTs’ operational range into terahertz frequencies. … Graphene has rapidly changed its status from being an unexpected and sometimes unwelcome newcomer to a rising star and to a reigning champion. The professional skepticism that initially dominated the attitude of many researchers with respect to graphene applications is gradually evaporating under the pressure of recent developments. Still, it is the wealth of new physics—observed, expected, and hoped for—that is driving the area for the moment. Research on graphene’s electronic properties is now matured but is unlikely to start fading any time soon, especially because of the virtually unexplored opportunity to control quantum transport by strain engineering and various structural modifications. Even after that, graphene will continue to stand out in the arsenal of condensed matter physics. Research on graphene’s non-electronic properties is just gearing up, and this should bring up new phenomena that may well sustain, if not expand, the graphene boom.
So yes, it is all that cool, even I don’t know about your application.