Measurement of transient Raman spectrum on gas-gun loading platform and its application in liquid silane

Combining a low temperature liquidizing system with a transient Raman spectroscopy, a new experimental technique is established for the first time on a two-stage light-gas gun, and it is employed to study shock-compressed fluid silane. With this experimental technique, we first obtain a Raman peak shift relating to the Si-H stretching vibration mode of molecular liquid silane under shock loading conditions. The Raman peak of 2184 cm^-1 at an initial state of 0 GPa and 85 K moves to 2223.4 cm^-1 at a shocked state of 10.5 GPa and 950 K, and its full width of half maximum broadens from 33 cm^-1 to 118 cm^-1. The shocked temperature, calculated by the thermodynamic equation of state, is well consistent with that estimated by the Doppler broadening function.

Phase transition of shocked water up to 6 GPa:Transmittance investigation

The phase transition behaviors of the shocked water are investigated by employing an optical transmittance in-situ detection system.Based on the light scattering theory and phase transformation kinetics,the phase transition mechanism of the water under multiple shocks is discussed.The experimental data indicate that the evolution of the transmittance of the shocked water can be broadly divided into three stages:relaxation stage,decline stage,and recovery stage.In the early stage of the phase transition,the new phase particles began to form around the quartz/window interface.It should be mentioned that the water/ice phase boundary seems to move toward the liquid region in one experiment of this work.Due to the new phase core being much smaller than the wavelength of the incident light,the transmittance of the sample within the relaxation stage remains steady.The decline stage can be divided into the rapid descent stage and the slow descent stage in this work,which is considered as the different growth rates of the new phase particle under different shock loadings.The recovery stage is attributed to the emergence of the new phase particles which are bigger than the critical value.However,the influence of the size growth and the population growth of the new phase particles on the transmittance restrict each other,which may be responsible for the phenomenon that the transmittance curve does not return to the initial level.

Theoretics-directed effect of copper or aluminum content on the ductility characteristics of Al-based(Al_3Ti,AlTi,AlCu,AlTiCu_2)intermetallic compounds

First-principle simulations have been applied to investigate the effect of copper（Cu） or aluminum（Al） content on the ductility of Al3Ti,AlTi,AlCu,and AlTiCu2 alloys.The mechanical stable and elastic properties of Al-based intermetallic compounds are researched by density functional theory with the generalized gradient approximation（DFT-GGA）.The calculated lattice constants are in conformity with the previous experimental and theoretical data.The deduced elastic constants show that the investigated Al_3Ti,AlTi,AlCu,and AlTiCu2 structures are mechanically stable.Shear modulus,Young＇s modulus,Poisson＇s ratio,and the ratio B/G have also been figured out by using reckoned elastic constants.A further analysis of Young＇s modulus and Poisson＇s ratio reveals that the third added element copper content has significant effects on the Al-Ti-based ICs ductile character.

A Density Functional Theory Study of Codoping Characteristics of Sulfur with Alkaline Earth in Delafossite CuAlO_2

The structural,electronic properties and formation energies of sulfur and alkaline earth codoped delafossite CuAlO_2 have been investigated using the first-principles density functional theory calculations.Our results reveal that the volume of codoping systems increases with the increasing atomic radius of metal atoms.The formation energies under different growth conditions have been calculated,showing that the codoping systems are formed easily under O-rich growth conditions.Electronic band structures and density of states have been obtained.The decreased bandgaps,enhanced covalence and appearance of electron acceptors after codoping are all good for p-type conductivity.