No abstract

Reticularly structured HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) of nano-size particles was simply prepared by reprecipitation at room temperature. The sample prepared by reprecipitation was characterized by SEM, TEM, XRD, DSC, and drop weight impact. The results of SEM and TEM indicated that spherical HMX particles of about 50 nm in diameter aggregated into reticularly structured conglomerates. There are two phases (g-and b-HMX) existing in the reticularly structured HMX as shown in the XRD pattern. It was also proved by DSC that the maximum energy release during decomposition of the reticularly structured HMX is at lower temperature. In addition, the testing result of drop weight impact showed that the reticularly structured HMX is less sensitive to impact.

No abstract

In this study, we have developed a novel multiscale simulator for a dye-sensitized TiO2 porous electrode. In the simulator, we can estimate the properties of the dye-sensitized TiO2 porous electrode using the three-dimensional mesoscopic structure model constructed on the basis of our original porous structure simulator. The microscopic physical properties of the materials were estimated by quantum chemistry calculation using a tight-binding quantum chemical molecular dynamics program. From the calculation results, we determined the absorption coefficient and the diffusion coefficient of excited carriers used in the macroscopic simulation for photoelectrode characteristics. By using this multiscale simulator, we will be able to determine the best electrode system efficiently.

In order to understand the behavior of electrons in complex porous structures, we have simulated electron diffusion processes in complex porous structures that have been fabricated using a system for a three-dimensional porous structure simulator, POCO 2 . For a given porosity, as the overlap ratio representing a necked porous TiO 2 structure increased, the coordination number of TiO 2 particles increased, resulting in an increase in electron flux and a decrease in trapping time. To gain better insights, we simulated the diffusion of electrons using models with different particle size distributions. This study shows that for a narrower size distribution of TiO 2 particles, a better electron diffusion process is realized. This result can be ascribed to the formation of a better TiO 2 coordination network. Consequently, through this study, we have shown that a well-formed neck between TiO 2 particles improves the electron diffusion properties of a complex porous material.