排序方式: 共有136条查询结果,搜索用时 31 毫秒
71.
在对Grüneisen系数高温高压特性不作任何假设的前提下,由冲击雨贡纽数据直接确定了材料零温零压体积、等温体模量及其对压力的一阶偏导。基于上述参数,计算了两种常用压标材料金和铂压缩比至0.5~0.6的0 K物态方程,并通过相应的热压修正得到了金和铂的室温等温物态方程。计算结果与准静水压条件下静高压实验结果具有非常好的吻合性,缩小了早期不同金和铂压标之间的差异。独立来源实验数据和理论计算结果的交叉检验表明,金和铂的室温等温物态方程计算结果可以用于今后静高压实验的压标。 相似文献
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First-Principles Calculations for Elastic Properties of ZnS under Pressure 总被引:2,自引:0,他引:2 下载免费PDF全文
The pressure dependence of elastic properties of ZnS in zinc-blende (ZB) and wurtzite (WZ) structures are investigated by the generalized gradient approximation (GGA) within the plane-wave pseudopotential density functional theory (DFT). Our results are in good agreement with the available experimental data and other theoretical results. From the high-pressure elastic constants obtained, we find that the ZB and WZ structures of ZnS are unstable when the applied pressures are larger than 15.8 GPa and 21.3 GPa, respectively. The sound velocities along different directions for the two structures are also obtained. It is shown that as pressure increases, the sound velocities of the shear wave decrease, and those of all the longitudinal waves increase. An analysis has been made to reveal the anisotropy and highly noneentral forces in ZnS. 相似文献
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The electronic, optical and thermodynamic properties of ZnS in the zinc-blende (ZB) and wurtzite (WZ) structures are investigated by using the plane-wave pseudopotential density functional theory (DFT). The results obtained are consistent with other theoretical results and the available experimental data. When the pressures are above 20.5 and 27 GPa, the ZB-ZnS and the WZ-ZnS are converted into indirect gap semiconductors, respectively. The critical point structure of the frequency-dependent complex dielectric function is investigated and analysed to identify the optical transitions. Moreover, the values of heat capacity Cv and Debye temperature θ at different pressures and different temperatures are also obtained successfully. 相似文献
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锆在常态为六角密堆(Hexagonal close-packed,hcp)结构(α相),在高压下转变成六方结构(ω相),温度升高时(1136K以上)转变为体心立方(Body-centered-cubic,bcc)结构(β相),更高温度(2123K)下熔化。锆在较低压力下发生α→β相变,材料强度影响不可忽略,研究表明材料在屈服后发生相变,会对已有的塑性流动起增强作用。本构关系对于研究锆在冲击加载下相变前后、相变期间的物理和力学性质的变化,理解锆的基本动力学特性是必不可少的。 相似文献
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自由电子气模型计算金属材料冲击压缩极限压缩度 总被引:2,自引:0,他引:2
用简单的自由电子气模型对金属铁、铜、铝、铅的冲击压缩特性进行了数值计算,计算结果表明材料并不能无限地被压缩,存在极限压缩度,随着压缩度的增加,在冲击压力增加的同时,冲击温度也急剧上升,限制了材料的进一步压缩,本文计算的这几种材料的极限压缩度为3.9. 相似文献
76.
A correction of Walsh's method for bulk sound velocity calculation for shocked porous materials is accomplished based on the Wu-Jing thermodynamic equation of state. The corrected bulk velocities for solid and porous samples with low porosities are in good agreement with the corresponding experimental data published previously. On the basis of this corrected equation, the influence of thermoelectrons on the bulk velocity of shocked materials is discussed in detail at pressures of 50, 70 and 200 GPa. Some interesting phenomena are revealed, which seem to be the unique features of a dynamic-pressure-loading process and could not be found in static experiments. 相似文献
77.
Shell-model molecular dynamics method is used to study the melting temperatures of MgO at elevated temperatures and high pressures using interaction potentials. Equations of state for MgO simulated by molecular dynamics are in good agreement with available experimental data. The pressure dependence of the melting curve of MgO has been calculated. The surface melting and superheating are considered in the correction of experimental data and the calculated values, respectively. The results of corrections are compared with those of previous work. The corrected melting temperature of MgO is consistent with corrected experimental measurements. The melting temperature of MgO up to 140GPa is calculated. 相似文献
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