AA'-graphite is an

allotrope of carbon Carbon is capable of forming many allotropes (structurally different forms of the same element) due to its valency ( tetravalent). Well-known forms of carbon include diamond and graphite. In recent decades, many more allotropes have been disc ...

similar to

graphite Graphite () is a Crystallinity, crystalline allotrope (form) of the element carbon. It consists of many stacked Layered materials, layers of graphene, typically in excess of hundreds of layers. Graphite occurs naturally and is the most stable ...

, but where the layers are positioned differently to each other as compared to the order in graphite. AA’ stacking of

graphene Graphene () is a carbon allotrope consisting of a Single-layer materials, single layer of atoms arranged in a hexagonal lattice, honeycomb planar nanostructure. The name "graphene" is derived from "graphite" and the suffix -ene, indicating ...

planes is another crystalline form of graphite (

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...

, Fig. 1) which is

metastable In chemistry and physics, metastability is an intermediate energetic state within a dynamical system other than the system's state of least energy. A ball resting in a hollow on a slope is a simple example of metastability. If the ball is onl ...

for Bernal AB graphite (

hexagonal In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A regular hexagon is d ...

) (Fig. 2) and reveals a

nanocrystalline A nanocrystalline (NC) material is a polycrystalline material with a crystallite size of only a few nanometers. These materials fill the gap between amorphous materials without any long range order and conventional coarse-grained materials. Defi ...

feature. Dr. Jae-Kap Lee discovered the new crystalline form of graphite in 2008 when he grew graphite onto diamond. He realized that graphene layers comprising graphite grew on

diamond Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of e ...

(111) plane with stacked in the sequence of AA', due to the crystallographic feature of diamond. The non-Bernal AA’ allotrope of graphite is synthesized by the thermal- and plasma-treatment of graphene nanopowders at ~1,500 °C. The formation of AA’ bilayer graphene nuclei facilitates the preferred texture growth and results in single-crystal AA’ graphite in the form of

nanoribbon Nanoribbon may refer to: * Graphene nanoribbons * Silicene nanoribbons * Boron nitride nanoribbons * Gallium(III) oxide nanoribbons * titanate nanoribbons - see titanium dioxide Titanium dioxide, also known as titanium(IV) oxide or titania ...

s (1D) or microplates (2D) of a few nm in thickness. Kinetically controlled AA’ graphite exhibits unique nano- and single-crystalline feature and shows quasi-linear behavior near the K-point of the

electronic band structure In solid-state physics, the electronic band structure (or simply band structure) of a solid describes the range of energy levels that electrons may have within it, as well as the ranges of energy that they may not have (called ''band gaps'' or '' ...

resulting in anomalous optical and acoustic

phonon A phonon is a collective excitation in a periodic, elastic arrangement of atoms or molecules in condensed matter, specifically in solids and some liquids. In the context of optically trapped objects, the quantized vibration mode can be defined a ...

behavior (Fig. 3). Lee et al. also revealed that multi-wall carbon nanotubes (MWNT) is a type of AA’ graphite. That is, MWNTs are composed of AA’ stacked graphene helices rather than concentric tubes (to be linked later).

References

attribution This article contains content copied from {{harv, Lee, Kim, Hembram, Kim, 2016 licensed under CC-BY-4.0 license Graphite