高温高压下UH3结构稳定性及其冲击分解OA北大核心CSTPCD

Using statistical physical model,the equation of state of UH3 crystal and its chemical decomposition products were constructed in this paper.The phase diagram of UH3 at high temperature and high pressure was obtained by Gibbs free energy comparison,and the shock compression properties of UH3 with different initial densities were investigated.The results show that the chemical decomposition of UH3 crystals occurs at about 74.0 GPa under isothermal compression.Increasing the temperature promotes the chemical decomposition,but the influence of pressure on the chemical decomposition of UH3 is non-monotonic.Solid UH3 decomposes at 35-50 GPa under shock compression,and the chemical decomposition process is accompanied by obvious volume collapse,therefore,the Hugoniot of UH3 decomposition products lies below the isotherm,which is an abnormal phenomenon in comparison with ordinary metals or compounds.Moreover,the decomposition pressure of UH3 decreases with the increase of initial porosity.When the initial porosity is about 1.5,the decomposition products of UH3 are more difficult to compress than UH3 in crystal phase,thus showing a phenomenon similar to the abnormal expansion of large porosity materials under shock compression.These results enrich our understanding of dynamical compression behavior of UH3,and can serve as theoretical basis for further research on physical and chemical properties of actinide metal hydrides at high temperature and high pressure.