China Academy of Engineering Physics

About: China Academy of Engineering Physics is a facility organization based out in Mianyang, China. It is known for research contribution in the topics: Laser & Microstructure. The organization has 14158 authors who have published 12055 publications receiving 115810 citations. The organization is also known as: Ninth Institute of Second Ministry of Mechanical Industry & Ninth Institute of Ministry of Nuclear Industry.

Twin Induced Sensitivity Enhancement of HMX versus Shock: A Molecular Reactive Force Field Simulation

Abstract: We report the early events of a twinned HMX crystal, as well as a perfect one for a comparison purpose, shocked with various velocities in the range of 6–10 km/s for 50 ps by molecular dynamic simulations using the ReaxFF reactive force field and the multiscale shock technique. The simulations show that the twin enhances the shock sensitivity remarkably, in agreement with our recent experimental observation. That is, it exhibits a lower shock initiation stress, higher decomposition velocities, more temperature, and stress increases under the same shock conditions, relative to the perfect crystal. In addition, we find the twinning plane is hottest and the temperature decreases in terms of the distance apart from it after shock loaded earlier, suggesting possible hot spots preferred there.

Photocatalytic hydrogen production over Aurivillius compound Bi3TiNbO9 and its modifications by Cr/Nb co-doping

Abstract: In this work, we have applied Cr/Nb co-doping strategy to the wide band gap semiconductor Bi 3 TiNbO 9 and have performed a detailed investigation on the structure, optical and photocatalytic properties of these modified Aurivillius compounds Bi 3 Ti 1-2x Cr x Nb 1+x O 9 (x = 0, 0.1, 0.2, 0.3). Our results suggest that Cr/Nb doping slightly expand the unit cell of Bi 3 TiNbO 9 with a doping limit around 20%. The involvement of Cr/Nb dopants in the crystal structure significantly reduces the band gap of Bi 3 TiNbO 9 by nearly 1 eV. Photocatalytic experiments and photoelectrochemical measurements confirms the critical role of Cr/Nb dopants in improving photocatalytic hydrogen production and anodic photocurrent. More than two-fold enhancement in hydrogen production has been noticed for merely 10% Cr/Nb co-doping. The highest photocatalytic activity belongs to Bi 3 Ti 0.8 Cr 0.1 Nb 1.1 O 9 (x = 0.1) for full range illumination and to Bi 3 Ti 0.6 Cr 0.2 Nb 1.2 O 9 (x = 0.2) for visible light illumination, with apparent quantum efficiency (AQE) approaching 0.52% and 0.27%, respectively. DFT calculation discloses the role of Cr in forming a new valence band inside the band gap of Bi 3 TiNbO 9 . In addition, strong anisotropic phenomenon in charge transportation of Bi 3 TiNbO 9 is also verified by DFT, as both conduction band minimum (CBM) and valence band maximum (VBM) are buried in the [BiTiNbO 7 ] 2− perovskite slabs and charges are only allowed to migrate within the slabs.

Ultrasensitive SERS detection of trinitrotoluene through capillarity-constructed reversible hot spots based on ZnO–Ag nanorod hybrids

Abstract: A simple and efficient self-approach strategy was used to apply ultrasensitivity and self-revive ZnO–Ag hybrid surface-enhanced Raman scattering (SERS) sensors for the highly sensitive and selective detection of explosive TNT in both solution and vapour conditions. The good ultrasensitive sensing performance is a result of the abundant Raman hot spots, which were spontaneously formed in a reversible way by the self-approaching of flexible ZnO–Ag hybrid nanorods driven by the capillary force of solvent evaporation. Moreover, the enhancement effect was repeatedly renewed by the reconstruction of molecular bridges, which could selectively detect TNT with a lower limit of 4 × 10−14 M. In addition, TNT vapor was also tested under this sensor, whereby once the ZnO–Ag NRs hybrid substrate was dipped in TNT, this substrate could detect the existence of TNT even in 5 detection cycles via a capillarity-constructed reversible hot spots approach. Compared with other pure Ag-based SERS sensors, this ZnO–Ag hybrid SERS sensor could rapidly self-revive SERS-activity by simple UV light irradiation and could retain stable SERS sensitivity for one month when used for TNT detection. This stable and ultrasensitive SERS substrate demonstrates a new route to eliminate the oxidized inactive problem of traditional Ag-based SERS substrates and suggests promising use in the applications of such hybrids as real-time online sensors for explosives detection.

Ab initio investigation of single-layer high thermal conductivity boron compounds

Abstract: The discovery and design of materials with large thermal conductivities (${\ensuremath{\kappa}}_{L}$) is critical to address future heat management challenges, particularly as devices shrink to the nanoscale. This requires developing novel physical insights into the microscropic interactions and behaviors of lattice vibrations. Here, we use ab initio phonon Boltzmann transport calculations to derive fundamental understanding of lattice thermal transport in two-dimensional (2D) monolayer hexagonal boron-based compounds, h-BX ($X=\mathrm{N}$, P, As, Sb). Monolayer h-BAs, in particular, possesses structural and dispersion features similar to bulk cubic BAs and 2D graphene, which govern their ultrahigh room temperature ${\ensuremath{\kappa}}_{L}$ (1300 W/m K and 2000--4000 W/m K, respectively), yet here combine to give significantly lower ${\ensuremath{\kappa}}_{L}$ for monolayer h-BAs (400 W/m K at room temperature). This work explores this discrepancy, and thermal transport in the monolayer h-BX systems in general, via comparison of the microscopic mechanisms that govern phonon transport. In particular, we present calculations of phonon dispersions, velocities, scattering phase space and rates, and ${\ensuremath{\kappa}}_{L}$ of h-BX monolayers as a function of temperature, size, defects, and other fundamental parameters. From these calculations, we make predictions of the thermal conductivities of h-BX monolayers, and more generally develop deeper fundamental understanding of phonon thermal transport in 2D and bulk materials.