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Nanowire structures with high-density interfaces are considered to have higher radiation damage resistance properties compared to conventional bulk structures. In the present work, molecular dynamics (MD) is conducted to investigate the irradiation effects and mechanical response changes of GaAs nanowires (NWs) under heavy-ion irradiation. For this simulation, single-ion damage and high-dose ion injection are used to reveal defect generation and accumulation mechanisms. The presence of surface effects gives an advantage to defects in rapid accumulation but is also the main cause of dynamic annihilation of the surface. Overall, the defects exhibit a particular mechanism of rapid accumulation to saturation. Moreover, for the structural transformation of irradiated GaAs NWs, amorphization is the main mode. The main damage mechanism of NWs is sputtering, which also leads to erosion refinement at high doses. The high flux ions lead to a softening of the mechanical properties, which can be reflected by a reduction in yield strength and Young's modulus. [ABSTRACT FROM AUTHOR]

Nanowire structures with high-density interfaces are considered to have higher radiation damage resistance properties compared to conventional bulk structures. In the present work, molecular dynamics (MD) is conducted to investigate the irradiation effects and mechanical response changes of GaAs nanowires (NWs) under heavy-ion irradiation. For this simulation, single-ion damage and high-dose ion injection are used to reveal defect generation and accumulation mechanisms. The presence of surface effects gives an advantage to defects in rapid accumulation but is also the main cause of dynamic annihilation of the surface. Overall, the defects exhibit a particular mechanism of rapid accumulation to saturation. Moreover, for the structural transformation of irradiated GaAs NWs, amorphization is the main mode. The main damage mechanism of NWs is sputtering, which also leads to erosion refinement at high doses. The high flux ions lead to a softening of the mechanical properties, which can be reflected by a reduction in yield strength and Young's modulus. [ABSTRACT FROM AUTHOR]

Perovskite ferroelectrics (FEs) have high endurance to radiation. Strontium titanate (STO) (SrTiO3) is a kind of perovskite FE with a large dielectric constant, which has attracted a good deal of attention due to its excellent dielectric, photoelectric and optical properties. The proton radiation damage in STO thin films is investigated by computer simulations in this work. The threshold displacement energy is an important input parameter for Monte Carlo simulation based on a binary collision approximation model, so we first use molecular dynamics to calculate the averaged threshold displacement energy of Sr, O and Ti atom. The calculated values are 67, 50 and 136 eV, which are obviously larger than default value (25 eV) in the Stopping and Range of Ions in Matter (SRIM) code. The results of the SRIM simulation demonstrate the dependency of vacancy number and position distribution on the proton's energy and the angle of incidence. [ABSTRACT FROM AUTHOR]

By applying non-equilibrium molecular dynamics simulation, it is demonstrated that the thermal conductivity of the reported Si/Ge core-shell nanowires (NWs) can be further reduced by shell doping. The thermal conductivity of Si/Ge0.6Si0.4 core-shell NWs is only about 66% of that of Si/Ge core-shell NWs. By analyzing the participation ratios of eigenmodes, it is revealed that the large reduction in the thermal conductivity of Si/Ge0.6Si0.4 core-shell NWs stems from the strong localization of the phonon modes from 1.0 THz to 2.0 THz and the modes from 9.0 THz to 16.0 THz due to both impurity scattering and interface scattering associated with peculiar structure of shell doped silicon NWs. [ABSTRACT FROM AUTHOR]

Perovskite ferroelectrics have high endurance to radiation. In order to understand the mechanism at the atomic level, molecular dynamics simulation is applied to investigate the process of defects generation and displacement cascades in BaTiO3 crystal. The calculated average threshold displacement energy of O, Ba and Ti atom is 53 eV, 70 eV, and 119 eV, respectively, so the number of O defects is larger than that of Ba and Ti defects. Furthermore, the simulations show that the initial movement direction of the primary knock-on atom (PKA) has significant influence on the number of defects because of different collision type (glancing collisions or direct knocks), and the number of Frenkel defects does not simply increase with increasing PKA energy due to the annealing effect. This investigation of the collision cascades is helpful to understand the radiation damage in BaTiO3 crystal and may offer useful guidelines to the design and applications for the practical devices. [ABSTRACT FROM AUTHOR]