RESUMEN
The fuel leakage of fuel vehicles will exacerbate the occurrence of distresses on asphalt pavements, including peeling, chipping and potholes, especially under the synergistic effect of traffic load and environment. In this research, Sasobit, which is commonly used as a warm agent in asphalt, is selected as the anti-fuel erosion agent and incorporated into SBS-modified asphalt and its mixtures. Diesel and gasoline are selected as the fuel erosion media. Sasobit/SBS-modified asphalt binder and its mixtures are investigated for fuel erosion. The rheological properties of bitumen and the mechanical properties of asphalt mixtures are assessed. The experimental findings show that the dissolution velocity of SBS-modified asphalt with 3% Sasobit is 0.2%/min for diesel erosion, while it is 1.7%/min for gasoline erosion, lower than the control sample without Sasobit. Meanwhile, the rutting factor of Sasobit/SBS-modified asphalt decreases less than that of the control sample without Sasobit. Furthermore, the mass loss ratio after the Cantabro test of Sasobit/SBS-modified asphalt mixtures is 1.2% for diesel erosion, while it is 6.8% for gasoline erosion, lower than that of the control sample without Sasobit. The results of the mechanical properties for asphalt mixtures demonstrate that Sasobit can enhance the anti-fuel erosion performance. Moreover, the research results of the Sasobit modification mechanism show that Sasobit can form a microcrystalline structure in SBS-modified asphalt, which subsequently improves the anti-fuel of asphalt and its mixtures. This research provides a reference for anti-fuel erosion assessment methods and solutions to improve the anti-fuel erosion of asphalt pavement.
RESUMEN
A kind of graphene-based perfect absorber which can generate low-threshold and high-extinction-ratio optical bistability in the near-IR band is proposed and simulated with numerical methods. The interaction between input light and monolayer graphene in the absorber can be greatly enhanced due to the perfect absorption. The large nonlinear coefficient of graphene and the strong light-graphene interaction contribute to the nonlinear response of the structure, leading to relatively low switching thresholds of less than 2.5 MW/cm2 for an absorber with a Q factor lower than 1000. Meanwhile, the extinction ratio of bistable states in the absorber reaches an ultrahigh value of 47.3 dB at 1545.3 nm. Moreover, the influence of changing the structural parameters on the bistable behaviors is discussed in detail, showing that the structure can tolerate structural parametric deviation to some extent. The proposed bistable structure with ultra-compact size, low thresholds, high extinction ratio, and ultrafast response time could be of great applications for fabricating high-performance all-optical-communication devices.
RESUMEN
The high saturation current density and ultrafast heating modulation of graphene makes it a competitive candidate for future thermal emission source. However, the low emissivity and easy oxidation under high temperature in air limit graphene application in the spectral range from the visible to near infrared. Here, we report a visible graphene thermal emitter based on the metal Fabry-Pérot (FP) cavity, which can greatly enhance the emissivity of graphene at wavelength around 637 nm and protect graphene from oxidation. We investigate the temperature characteristics of the emitter, and find the temperature of hot electrons in graphene is much higher than that of graphene lattice. Moreover, we also demonstrate the wavelength and intensity of graphene emission could be controlled by tuning the dielectric thickness between two gold layers. These results are helpful in the development of advanced graphene electro-thermal emission controlling application.
RESUMEN
A very attractive advantage of graphene is that its Fermi level can be regulated by electrostatic bias doping. It is of great significance to investigate and control the spatial location of graphene emission for graphene thermal emitters, in addition to tuning the emission intensity and emission spectrum. Here, we present a detailed theoretical model to describe the graphene emission characteristics versus gate voltages. The experimentally observed movement of the emission spot and temperature distribution of graphene emitters are basically in agreement with those from the theoretical model. Our results provide a simple method to predict the behavior of graphene emitters that is beneficial for achieving the spatial dynamic regulation of graphene infrared emission arrays.
RESUMEN
2D semiconductors with atomically thin body thickness have attracted tremendous research interest for high-performance nanoelectronics and optoelectronics. Most of the 2D semiconductors grown by chemical vapor deposition (CVD) methods suffer from rather low carrier mobility, small single-crystal size, and instability under ambient conditions. Here, we develop an improved CVD method with controllable reverse-gas flow to realize the direct growth of quality Bi2O2Se 2D single crystals on a mica substrate. The applied reverse flow significantly suppresses the random nucleation and thus promotes the lateral size of 2D Bi2O2Se crystals up to â¼750 µm. The Bi2O2Se field-effect transistors display high-room-temperature electron mobility up to â¼1400 cm2·V-1·s-1 and a well-defined drain current saturation. The on/off ratio of the Bi2O2Se transistor is larger than 107, and the sub-threshold swing is about 90 mV·dec-1. The responsivity, response time, and detectivity of Bi2O2Se photodetectors approach up to 60 A·W-1, 5 ms, and 2.4 × 1010 Jones at room temperature, respectively. Our results demonstrate large-size and high-quality Bi2O2Se grown by reverse-flow CVD as a high-performance channel material for next-generation transistors and photodetectors.
RESUMEN
Broadband optical absorption structures in the near infrared by coupling monolayer-graphene with periodical metal structures are proposed and demonstrated numerically. Optical absorption of graphene with over-50%-absorption bandwidth up to hundreds of nanometer caused by magnetic dipole resonances and magnetic coupling effect are investigated in detail, and the demonstrated bandwidths are one order higher than those caused by dielectric guiding mode resonances. In addition, the influences of geometrical parameters of structures are fully analyzed and these demonstrated structures show angular-insensitive absorption for oblique incidence in a large angular range. The demonstrated absorption structures in this work provide new design ideas in the realization of advanced graphene-based optoelectronic devices.