Comparative graphene and carbon nanotubes and other synthetic materials, based on heavy hydrocarbons (HH) of the material (coal, tar, and pitch) is rarely used as a material of electronic and optoelectronic applications. However, in HH extensive chemical and structural heterogeneity provides a complex network of carbon nanostructures, these networks have built-in chemical and functional diversity but not yet utilized. Thus, a better understanding of the relationship between the HH alone or in mixtures the chemical nature and functions of materials, and their adjustability of the processed material, can better utilize HHs potential as an additive raw material, the physical custom synthesis materials and chemical properties. In fact, raw HHs mainly polycyclic aromatic hydrocarbons (PAHs), alkanes. Although HHs poor conductivity, but it can be compensated by the overall annealing, the conductivity of the graphitized by several orders of magnitude. Compared to traditional furnace annealing (mass loss> 80%), laser ablation, rapid heating to a graphitization temperature the rate of incorporation of the material almost immediately, to reduce loss of material (about 50%). Therefore, laser ablation allowed to explore fast pyrolysis, and loss of control material. In addition, the annealing method is not suitable for bulk spatially control the heating process, and they require the support substrate and the thin film can be maintained the same annealing temperature.
Based on this, Massachusetts Institute of Technology (MIT) in the JC Grossman and [ . 123] N Ferralis (co-author) coverage of initial carbon source – structure heterogeneous mixture HHs (especially aromatic, aliphatic and heteroatoms concentration) and a feature greatly affects the chemical structure and properties of the resulting carbon thin film, for example, porosity and conductivity. binding material Chemistry (H: C and an aromatic content) is selected, the control of the laser process parameters (laser power, speed, focal length) changes in , can fully control the product H: C ratio, SP2 concentration and graphitized stacking sequence. To achieve a large range of crystallinity carbon material from amorphous to highly graphitized regulation, and conductivity 10 3 S / m or more regulation range. The research results, entitled \”Laser-engineered heavy hydrocarbons: Old materials with new opportunities \”published in internationally renowned journals Sci Adv on
[graphic interpretation] [123… ] first, using a CO2 laser chemical researchers adjusted HHs, shape and electrical conductivity, including tar the steam cracking of oil
, low-volatile bituminous (LvB) coal , intermediate phase (the MP) asphalt , and mixtures thereof due to the tar (the tar) , and coal pitch H:. wide range of initial structure consistent C ratio, and a high aromatic content, they therefore chosen as a representative material of the intermediate contrast HHs mesophase pitch and coal tar having the highest H:. C and higher paraffin content is processed by a low pitch .MP formed thermotropic crystalline, isotropic pitch wherein is polymerized to a higher molecular weight having a higher ordinal number of aromatic structures with the lowest component .MP H: C and maximum aromatic content, and with a sheet neatly arranged aromatics, and aromatics LvB initial nucleus is the largest, intermediate H:. C and an aromatic content of more than
) and the highest peak 2D, but the ID / IG ratio with FWHM the increases.
In summary, researchers processing and controlling environmental parameters selected HH material in the laser annealing process, is widely demonstrated adjustable ablative performance, covering a range of crystal structure, conductivity and electron transport mechanism. Best conductivity and engineering structure by the molecular arrangement of the obtained stability permit manufacture of these devices. In essence, by different chemical and structural customized HH, the use of a simple material processing, carried out on the carbon engineering to achieve the desired level of device performance levels. In short, the development of treatment methods used in this work as a low-cost raw material directly HH provides scalable and inexpensive way of manufacturing a device as an active device layer or the additive has many potential applications. Document Link: Laser-engineered heavy hydrocarbons: Old materials with new opportunities (Sci Adv, 2020, DOI:.. 10.1126 / sciadv.aaz5231)