Raman Spectroscopy Of Graphite Research Articles

Kinetics Study and Degradation Analysis through Raman Spectroscopy of Graphite as a Negative-Electrode Material for Potassium-Ion Batteries

The development of K-ion batteries composed of abundant elements is a promising way to address the concerns generated by the resource constraint due to the increased demand for Li-ion batteries in ...

New preparation approach, electrical and mechanical properties of poly(vinyl alcohol)-loaded graphene films

Previous publications showed that graphene sheets polymer nanocomopsites were prepared by incorporating previously prepared graphene into the polymer matrix through two or more successive steps. In this work, graphene sheets were exfoliated from graphite inside the polymer matrix solution for certain period in one step. This approach was easy to perform, low cost, high mass production of graphene and, almost, produces effective results. In this respect, electrolytic solution from poly(vinyl alcohol) (PVA) and salt was prepared and exfoliation process took place inside it for different times. After that, solution was dried to get films of PVA loaded with different concentrations of graphene sheets. Scanning electron microscopic and transmission electron microscopic images of exfoliated graphene sheets were studied. Raman spectroscopy of graphite, graphene nanosheets, and PVA-loaded graphene was studied. The dielectric permittivity, dielectric loss, and alternating current electrical conductivity were studied and had maximum values at 10 min of exfoliation time. Cole–Cole impedance plots show semicircles behavior with lowest radius for samples prepared at 10 min. The elastic modulus was found to have a maximum value at exfoliation time of 30 min.

The Origin of Raman D Band: Bonding and Antibonding Orbitals in Graphene

In Raman spectroscopy of graphite and graphene, the D band at ∼ 1355 cm−1 is used as the indication of the dirtiness of a sample. However, our analysis suggests that the physics behind the D band is closely related to a very clear idea for describing a molecule, namely bonding and antibonding orbitals in graphene. In this paper, we review our recent work on the mechanism for activating the D band at a graphene edge.

Raman spectroscopy of graphene and graphite: Disorder, electron–phonon coupling, doping and nonadiabatic effects

We review recent work on Raman spectroscopy of graphite and graphene. We focus on the origin of the D and G peaks and the second order of the D peak. The G and 2 D Raman peaks change in shape, position and relative intensity with number of graphene layers. This reflects the evolution of the electronic structure and electron–phonon interactions. We then consider the effects of doping on the Raman spectra of graphene. The Fermi energy is tuned by applying a gate-voltage. We show that this induces a stiffening of the Raman G peak for both holes and electrons doping. Thus Raman spectroscopy can be efficiently used to monitor number of layers, quality of layers, doping level and confinement.

Raman spectroscopy of graphite

We present a review of the Raman spectra of graphite from an experimental and theoretical point of view. The disorder-induced Raman bands in this material have been a puzzling Raman problem for almost 30 years. Double-resonant Raman scattering explains their origin as well as the excitation-energy dependence, the overtone spectrum and the difference between Stokes and anti-Stokes scattering. We develop the symmetry-imposed selection rules for double-resonant Raman scattering in graphite and point out misassignments in previously published works. An excellent agreement is found between the graphite phonon dispersion from double-resonant Raman scattering and other experimental methods.

Fluid-present anatexis of metapelites at El Joyazo (SE Spain): constraints from Raman spectroscopy of graphite

The garnet-biotite-sillimanite anatectic xenoliths in the Neogene dacite dome of El Joyazo (also called Cerro de Hoyazo, SE Spain) contain four types of graphite (I to IV), distinguished on the basis of grain size and texture. Structural characterization of graphite by Laser Raman spectroscopy (LRS) shows systematic differences in the degree of ordering among the four types: only type III is fully consistent with the granulite-facies conditions reached by the xenoliths during partial melting, the others indicate metamorphic temperatures covering amphibolite-facies conditions, with only a few examples of granulite-grade crystallinity. All graphite crystallized before or during the anatectic event, indicating that a large fraction of the graphite did not equilibrate at peak temperatures. The mm-scale coexistence of different types and degrees of ordering in the graphite suggests different origins, i.e. of biogenic derivation and “fluid-deposited”, and is explained in terms of fluid-melt-graphite interaction during the anatectic event. Disequilibrium behaviour during high-temperature metamorphism and anatexis is typical of types I, II and particularly of IV, and is attributed to sluggish kinetics of solid-state graphitization, mainly owing to the limited time of the process and carbon saturation of the intergranular fluid. The coexisting, well-ordered type III graphite is the product of melting in the presence of a graphite-saturated fluid, a process that would account for the deposition of new graphite. The LRS results, together with petrologic observations, suggest that it is possible that high melt fractions can be generated by fluid-present melting of a metasedimentary protolith also in a closed system. Although this contradicts the commonly accepted hypothesis that, due to limited rock porosities, extensive fluid-present melting is precluded unless infiltration occurs, it is a possible end-member model in anatectic settings characterized by rapid heating rates and low-grade source rocks.

Raman spectroscopy of graphite and carbon materials and its recent application

Raman spectroscopy of graphite and carbon materials and its recent application

Raman Spectroscopy of Graphite and Carbon Materials and Its Recent Application

Recent study of the Raman spectroscopy for graphite and carbon materials were reviewed, including the explanation for the structural-sensitive spectrum, the results of the measurements with very high signal-to-noise ratio, the excitation wavelength dependence, the method for the characterization of texture and microstructure and the Raman microprobe application. Some issues were also pointed out to utilize the structural-sensitive Raman spectroscopy to characterization of a variety of carbon materials.

Raman spectroscopy of graphite in cast iron

AbstractThe Raman scattering spectra of carbon inclusions found in two cast iron samples were studied. From the observed spectra it was deduced that this carbon is made of good‐quality microcrystals, 5 nm in size, in the planes of the threefold coordinated carbon.