Calculation of Electronic Structure of Anatase TiO_2 Doped with Transition Metal V,Cr,Fe and Cu Atoms by the Linearized Augmented Plane Wave Method

The electronic density of states and band structures of doped and un-doped anatase TiO2 were studied by the Linearized Augmented Plane Wave method based on the density functional theory. The calculation shows that the band structures of TiO2 crystals doped with transition metal atoms become narrower. Interesting, an excursion towards high energy level with increasing atomic number in the same element period could be observed after doping with transition metal atoms.

Theoretical Calculations for Structural, Elastic and Thermodynamic Properties of γTiAl Under High Pressure

We investigate the structural and elastic properties of γ TiAl under high pressures using the norm-conservingpseudopotentials within the local density approximation(LDA)in the frame of density functional theory.The calculatedpressure dependence of the elastic constants is in excellent agreement with the experimental results.The elastic constantsand anisotropy as a function of applied pressure are presented.Through the quasi-harmonic Debye model,we alsoinvestigate the thermodynamic properties of γ TiAl.

Triatomic wake effect and the determination of the molecular structure of HD_2^+ from the Coulomb explosion

A new theoretical model of the triatomic molecular wake effect is proposed and applied to molecular ions D^＋3 and HD^＋2 while passing through a solid. The wake effects resulting from the reactions of the two similar ions with thin carbon foil are also investigated by using the Coulomb explosion technique. The experimental results are in good agreement with theoretical estimates and the molecular structure of HD^＋2 is determined by using the model.

Influence of defect states on band gaps in the two-dimensional phononic crystal of 4340 steel in an epoxy

The band structures of a new two-dimensional triangle-shaped array geometry of 4340 steel cylinders of square cross section in an epoxy resin were studied by the plane-wave expansion and supercell calculation method. The band gaps of this type of phononic crystals with different defects were calculated such as defect-free, 60° crystal linear defect states, 120° crystal linear defect states, and 180° crystal linear defect states. It was found that the band gap will emerge in different linear defects of the phononic crystals and the bandwidth of linear defect states is larger than that of the free-defect crystal by about 2.14 times within the filling fraction F = 0.1-0.85. In addition, the influence of the filling fraction on the relative width of the minimum band gap is discussed.

Cooling Curve of Strange Star in Strong Magnetic Field

在这篇论文，第一，我们在强壮的磁场从夸克 Urca 过程调查中微子放射率。然后，我们在强壮的磁场讨论奇怪的星的热能力。最后，我们在强壮的磁场给冷却曲线。以便做比较，我们也在空磁场的情况中给相应冷却曲线。没有磁场，结果奇怪的星比那在强壮的磁场更快冷却。

Influence of Mn Doping on the Sensing Properties of SnO₂Nanobelt to Ethanol

Mn doped SnO2 nanobelts (Mn:SnO2 NBs) and pure SnO2 nanobelts (SnO2 NBs) were synthesized by thermal evaporation technique at 1355°C with Ar carrier gas (25 sccm, 150 Torr). The SEM, EDS, XRD, TEM, HRTEM, SAED, XPS, UV-Vis techniques were used to characterize the attained samples. The band gap of Mn doped SnO2 NBs by UV-Vis was measured to be 3.43 eV at room temperature, lower than that of the pure counterpart with ~3.66 eV. Mn:SnO2 NB and pure SnO2 NB sensors were developed. It is found that Mn:SnO2 NB device exhibits a higher sensitivity with 62.12% to 100 ppm of ethanol at 210°C, which is the highest sensitivity among the three tested VOC gases (ethanol, ethanediol, and acetone). The theoretical detection limit for ethanol of the sensor is 1.1 ppm. The higher response is related to the selective catalysis of the doped Mn ions.

The Magnetic Properties of Zn_0.98Fe_0.02O with Additional Cu Doping

Samples Zn0.98Fe0.02O doped with additional Cu have been fabricated by a coprecipitation method. It is found that Zn0.98Fe0.02O without additional doping shows weak ferromagnetism at room temperature. The Cu doping has induced a light increase of magnetization in low temperature of 10 K. This result is consistent with bound magnetic polaron model relative to holes.

High-response formamidine bromide lead hybrid cadmium sulfide photodetector

Organic-inorganic hybrid perovskite formamidinium lead bromide nanosheet(FAPb Br_(3)NS)is regarded as a superior substance used to construct optoelectronic devices.However,its uncontrollable stability seriously affects its application in the field of photodetectors.In this paper,FAPb Br_(3)is combined with cadmium sulfide nanobelt(Cd S NB)to construct a hybrid device that greatly improves the stability and performance of the photodetector.The response of the FAPb Br_(3)NS/Cd S NB detector under 490 nm light illumination reaches 5712 A/W,while the response of the FAPb Br_(3)photodetector under equivalent conditions is only 25.45 A/W.The photocurrent of the FAPb Br_(3)NS/Cd S NB photodetector is nearly 80.25%of the initial device after exposure to air for 60 days.The difference in electric field distribution between the single material device and the composite device is simulated by the finite-difference time-domain method.It shows the advantages of composite devices in photoconductive gain and directly promotes the hybrid device performance.This paper presents a new possibility for high stability,fast response photodetectors.

Mn single-atoms decorated CNT electrodes for high-performance supercapacitors

Developing highly robust and efficient electrode materials is of critical importance to promoting the energy density of current supercapacitors for commercialization.Herein,we report an efficient catalyst with monodispersed Mn single-atoms embedded in carbon nanotubes(Mn-CNTs)for enhancing the electrode performance of supercapacitors.A high specific capacitance(1523.6 F·g^(-1) at 1.0 A·g^(-1))can be achieved,which is about twice as high as the specific capacitance of the electrode material without the introduction of Mn single-atoms.Remarkably,the asymmetric electrochemical capacitor created with Mn-CNT and activated carbon exhibits a high energy density of 180.8 Wh·kg^(-1) at a power density of 1.4 kW·kg^(-1),much higher than most reported results.The study shows that the integration of Mn atoms into the CNT can enhance the charge transport capacity and the number of polar active sites of Mn-CNT and then facilitate chemical interactions between Mn-CNT and OH-.This work provides a novel strategy to enable high-energy storage in supercapacitors by introducing single-atoms into carbon nanotubes to improve electrodes’energy density and cycle life.

Light controlled prebreakdown characteristics of a semi-insulating GaAs photoconductive switch

A 4 mm gap semi-insulating （SI） GaAs photoconductive switch （PCSS） was triggered by a pulse laser with a wavelength of 1064 nm and a pulse energy of 0.5 mJ. In the experiment, when the bias field was 4 kV, the switch did not induce self-maintained discharge but worked in nonlinear （lock-on） mode. The phenomenon is analyzed as follows： an exciton effect contributes to photoconduction in the generation and dissociation of ex- citons. Collision ionization, avalanche multiplication and the exciton effect can supply carrier concentration and energy when an outside light source was removed. Under the combined influence of these factors, the S1-GaAs PCSS develops into self-maintained discharge rather than just in the light-controlled prebreakdown status. The characteristics of the filament affect the degree of damage to the switch.

Boundary element method of hydrodynamic characteristics of lubricant in three-leaf dislocated floating-ring bearing

The problem of hydrodynamics of the three-leaf dislocated floating-ring bearing was studied by means of boundary element method.The law including the distribution of pressure on boundary surface(axial,bearing and floating-ring)and its friction loss in different eccentricities was obtained.The results show that the inner friction of three-leaf dislocated bearing increases from 390.875to 1 091.65,and the inner friction of three-leaf dislocated floating-ring bearing increases from 94.2523to 114.5069with eccentricity varying from 0to 0.075in nondimensional.So changing the pressure and flow field of bearing by adding floating-ring is more stability and less wasted work of friction than three-leaf dislocated bearing.

Experimental investigation of limit space charge accumulation mode operation in a semi-insulating GaAs photoconductive semiconductor switch

Experiments with the limited space-charge accumulation（LSA） mode of oscillation in a large gap semiinsulating （SI） GaAs photoconductive semiconductor switch（PCSS） are discussed.It has been observed that growth and drift of a photo-activated charge domain（PACD） are quenched only when the bias voltage is more than twice the threshold voltage.The original negative resistance characteristics are directly utilized in the LSA mode;during LSA operation the spatial average of the electric field varies over a large portion of the negative differential mobility region of the velocity-electric field characteristic.The work efficiency of an SI GaAs PCSS is remarkably enhanced by electric field excursions into the positive resistance region when the total electric field is only below the threshold part of the time.The LSA mode can only operate in the certain conditions that satisfy the quenching of the accumulation layer and the smaller initial domain voltage.

Air-coupled ultrasonic infrared thermography for inspecting impact damages in CFRP composite

Ultrasonic thermography or thermosonics is proved to be an effective non-destructive testing （NDT） method for inspecting carbon-fiber-reinforced polymer （CFRP） composites; however, the potential dam- ages for the structure cannot be ignored, because of the contact vibration between the ultrasonic horn and the specimen. This work aims at developing a new excitation method for ultrasonic thermography--air- coupled ultrasonic excitation. CFRP laminates with impact damages are tested by air-coupled ultrasonic thermography, and the theoretical model of heat conduction is given. Results demonstrate good excitation performance for impact damages detection in CFRP composites. Moreover, the conventional ultrasonic thermography results are shown, and the prospect of air-coupled ultrasonic thermo^raphv is discussed.