First-Principles Calculations on Structural Property and Anisotropic Elasticity of γ1-Ti4Nb3Al9 under Pressure.

The effect of pressure on the structural property and anisotropic elasticity of γ 1 -Ti 4 Nb 3 Al 9 phase has been investigated in this paper by using first-principles calculations. The obtained bulk properties at zero pressure are in good agreement with the previous data. The structural property and elastic constants under pressures up to 40 GPa have been obtained. According to the elastic stability conditions under isotropic pressure, the phase is found to be mechanically stable under pressures up to 37.3 GPa. From the obtained elastic constants, the elastic moduli, anisotropic factors and acoustic velocities under different pressures have also been obtained successfully together with minimum thermal conductivities and Debye temperature. It is shown that the ductility of the phase is improved and its anisotropy and Debye temperature are enhanced with increasing the pressure.

Pressure Effect on Elastic Constants and Related Properties of Ti3Al Intermetallic Compound: A First-Principles Study.

Using first-principles calculations based on density functional theory, the elastic constants and some of the related physical quantities, such as the bulk, shear, and Young's moduli, Poisson's ratio, anisotropic factor, acoustic velocity, minimum thermal conductivity, and Debye temperature, are reported in this paper for the hexagonal intermetallic compound Ti 3 Al. The obtained results are well consistent with the available experimental and theoretical data. The effect of pressure on all studied parameters was investigated. By the mechanical stability criteria under isotropic pressure, it is predicted that the compound is mechanically unstable at pressures above 71.4 GPa. Its ductility, anisotropy, and Debye temperature are enhanced with pressure.

Narrowband ultraviolet photodetector based on MgZnO and NPB heterojunction.

An ultraviolet photodetector was fabricated based on Mg0.07Zn0.93O heterojunction. N, N'-bis (naphthalen-1-y1)-N, N'-bis(pheny) benzidine was selected as the hole transporting layer. I-V characteristic curves of the device were measured in the dark and under the illumination of 340 nm UV light with density of 1.33 mW/cm2. The device showed a low dark current of about 3×10(-10) A and a high photo-dark current ratio of 1×10(5) at -2 V bias. A narrowband photoresponse was observed from 300 to 400 nm and centered at 340 nm with a full width at half-maximum of only 30 nm. The maximum peak response is at 340 nm, which is 0.192 A/W at the bias of -1 V.

High response organic deep ultraviolet photodetector with PEDOT:PSS anode.

We have fabricated an organic deep ultraviolet photodetector (PD) using PEDOT:PSS (PH 1000) as a transparent anode. NPB and PBD were employed as electron donor and acceptor, respectively. The PD exhibits a dark current of 0.0829 µA/cm(2) and a photocurrent of 85.3 µA/cm(2) at -12 V under 280 nm light illumination with an intensity of 0.488 mW/cm(2). A high response at 248-370 nm with its peak of 0.18 A/W at 280 nm and a detectivity of 1.1×10(12) cm Hz(1/2) W(-1) were achieved. The more detailed mechanism of harvesting high performance and the dependence of photocurrent density on illumination intensity are also discussed.