共查询到20条相似文献,搜索用时 484 毫秒
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利用量子分子动力学方法对氘、氦及其混合物的状态方程进行了研究. 计算了氦在密度0.32-5 g/cm3, 温度1000-50000 K范围内的状态方程, 并与化学模型的结果进行了比较; 同时计算了冲击Hugoniot曲线, 与气炮实验的结果符合得很好. 通过计算对分布函数及态密度, 探讨了氦在高温高压下发生金属-绝缘体转变的机理. 计算了氘在密度0.19-0.84 g/cm3, 温度20-50000 K范围内的状态方程; 并计算了理论Hugoniot状态, 由于没有考虑原子的零点运动, 在低温区, 理论结果比实验值小. 对氘氦混合物的状态方程进行了研究, 计算了温度和密度区间为100-50000 K, 0.19-0.84 g/cm3, 不同混合度下的293个状态点的状态方程. 对线性混合近似进行了考查, 结果表明线性混合近似是一个粗略的近似. 相似文献
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王义 《原子与分子物理学报》2000,17(2):358-362
以GGA -LAPW冷能计算为基础 ,应用经典统计理论计算了铁的Hugoniot性质 ,包括 :P -V曲线、P -T曲线、热容、Grueneisen参数。计算结果基本上与实验符合。 相似文献
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在火炮和二级轻气炮上利用反向碰撞技术,通过测量飞片击靶速度以及飞片/窗口的界面粒子速度,获得了金属铋(Bi)在10-45 GPa压力范围内的Hugoniot数据. 该方法克服了电探针法在测量低压Hugoniot数据时由于导通一致性差而不能准确得到冲击波速度的难题,同时又避免了精确测量样品中冲击波走时的问题. 实验获得的冲击波速度(D)-波后粒子速度(u)Hugoniot数据表明,Bi在粒子速度u=0.9 km/s附近D-u曲线发生了明显拐折,产生这一拐折的原因推测与冲击导致的Bi的固-液相变有关.
关键词:
Hugoniot数据
反向碰撞
冲击相变
铋 相似文献
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根据Grüneisen物态方程、Hugoniot内能守恒方程和最新发表的铁的热物理参数,计算了ε-(hcp)铁和液态铁的理论Hugoniot曲线。计算的Hugoniot曲线与最新修正的铁的实验数据[J Appl Phys, 2000, 88: 5496]在总体上符合很好,并且可以细分为两个部分:在约低于200 GPa的压强区,用ε-铁模型的计算结果与实验结果符合很好;在约高于260 GPa的压强区,用液态铁模型的计算结果与实验数据也符合得比较好;对介于200~260 GPa之间的压强区,则归属于由ε-铁向液态铁转变的混合相区。这意味着铁的Hugoniot曲线在约200 GPa处出现的微小偏折是由固-液相变引起的,从而否定了Brown [Geophy Res Lett, 2001, 28: 4339]提出的它是一次由ε-铁向另一个未知结构的某个固相铁的相转变的见解。 相似文献
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派热克斯玻璃的Hugoniot实验数据显示了在20GPa以下存在相变,我们认为这是一种固态-固态的一级相变,根据Gibbs相平衡条件并应用了相变前的低压物态方程,计算了这种固态-固态相变的熵增。计算表明熵增为负值,即相变为放热过程。在此基础上给出了相变区的物态方程,其中冷压为平台,内能计入了相变熵的影响。由相变区的物态方程得到的理论的与实验的Hugoniot曲线基本一致。 相似文献
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本文通过对三十四种金属元素冲击压缩实验数据的综合,借助于对应态原理的对比方法,归纳得到了描述金属元素冲击压缩规律的普适经验公式——对比Hugoniot线;运用德拜近似理论,从所得到的对比Hugoniot线导出了对金属元素普适的高压状态方程。由此普适状态方程计算了镁、钒、铁、铜等十五种金属元素的冲击压缩线,计算结果与动力冲击压缩实验数据进行比较,符合情况较好。
关键词: 相似文献
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氮的高温高压物态方程以及相图对于研究和制备高能量密度含能材料至关重要.本文采用基于密度泛函理论的分子动力学模拟方法,研究了液氮的高温高压行为,给出900—25000 K, 2—200 GPa区间流体氮的物态方程以及组分、相态变化.在上述相空间,观察到流体氮分子相-聚合物相以及聚合物-原子相的相变发生.获得的液氮Hugoniot理论曲线与实验结果吻合较好,发现30—60 GPa区间Hugoniot曲线的软化与分子-聚合物流体相的相变有关;在60 GPa后Hugoniot曲线变陡峭与流体氮进入聚合物相区有关. 相似文献
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John A. Moriarty 《高压研究》2013,33(6):343-365
Abstract Using accurate electronic-structure, interatomic-potential, and statistical methods, first-principles theoretical equations of state (EOSs) have been developed for the prototype metals Al, Cu, Mo, and Pb over wide ranges of volume and temperature. Emphasis is given to both the cold compressed solid, relevant to diamond-anvil-cell (DAC) experiments, and to the hot compressed liquid, relevant to multimegabar shock-wave experiments. The A1 EOS has recently been used to analyze nuclear-impedance-match (NIM) shock data on AI-Cu, AI-Mo, and A1-Pb sample pairs in the 5–30 Mbar regime [J. Appl. Phys. 69, 2981 (1991)]. Below 10 Mbar, calculated theoretical Hugoniots are in very good agreement with both absolute and NIM shock data for all four metals. Above 10 Mbar, some quantitative uncertainties remain, especially for Mo. Useful analytic representations of the calculated 300-K isotherms below 10 Mbar have also been developed for fcc Al, Cu, and Pb and for bcc Mo. The theoretical isotherms are in excellent agreement with a variety of ultrasonic, DAC, and reduced-shock data obtained in the assumed phases below 3 Mbar. At higher pressures complicating solid-solid phase transitions are expected and/or observed in Al, Mo, and Pb, but not in Cu, which is consequently a good candidate as a static ultrahigh-pressure EOS standard. 相似文献
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��ҫ�£������ԣ��� 《核聚变与等离子体物理》2015,35(3):198-203
The cold pressure parameters of q and Q in the Born-Mayer(BM) model for fifty-seven metals equations were calculated by using the Hu-Jing(HJ) method based on isothermal bulk moduli of metal and measured data in shock wave experiments, and at the same time a trial method for computing them by combining Thomas-Fermi model at absolute zero-temperature with low pressure experiment data, is put forward for lack of the sufficient shock wave experiment data. By integrating the Faussurier model for electron thermal pressure, the Cowan model for ion thermal pressure and the above obtained cold pressure fitted formula, the Hugoniot curves of Be, Co and Pb are calculated and compared with experimental data, and then the discrepancies of q value and Q value obtained by HJ method and a comprehensive method are analyzed and interpreted. Furthermore, the precision for the cold pressure equation by HJ method is assessed by comparing the thermodynamic quantities on the Hugoniot curves of Sr, Ba, and Sm with the corresponding measured results and the calculated ones by other models. 相似文献
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在金属等温体积模量和冲击波动态压缩实验数据基础上,利用胡-经(HJ)方法计算了57 种金属材料在Born-Mayer(BM)模型中冷压参数q 和Q,同时提出了在没有足够实测冲击波数据前提下结合零温 Thomas-Fermi(TF)模型与低压实验数据计算冷压参数的试探法。组合Faussurier 电子热压模型、Cowan 离子热压模型和以上方法得到的冷压拟合式,通过对Be、Co 和Pb 的计算和实验的冲击绝热数据的对比,分析了HJ 法与综合优选法得到的q 和Q 之间的差异。进一步计算了Sr、Ba 和Sm 材料沿冲击绝热曲线上的热力学量,通过与相应的实测结果以及与其他模型对比来评估HJ 冷压方程的精度。 相似文献
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Eugene N. Avrorin 《高压研究》2013,33(1-6):822-825
Abstract Different theoretical models giving information about equations of state near 100 Mbar pressure are discussed. Experiments providing data on the shock compressibility of Al, Fe, Pb are described. An international superhigh pressure equation of state experiment is proposed. 相似文献
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T. Neal 《Journal of Physics and Chemistry of Solids》1977,38(3):225-231
The term second Hugoniot is used to describe a locus of states directly attainable by shock compression beginning with an initial state that has itself been achieved by shock compression. For many materials the principal Hugoniot is linear in the shock velocity-particle velocity [Us — up] representation. A second Hugoniot for such materials is not linear in this representation, but the nonlinear effects can often be neglected if the compressions are not too great. These results are based on the Mie-Grüneisen equation of state and are more or less independent of the explicit functional dependence of the Grüneisen parameter. A criterion to evaluate the magnitude of nonlinear effects is posed and Mg and Pb are treated as examples. Calculated second Hugoniots are compared with experimental results for regular reflection in Mg, Pb and U. For these materials nonlinear effects are not important from a practical standpoint for final volumetric compressions to roughly two-thirds of the initial volume. Some future experimental work is also suggested. 相似文献
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Abstract A high intensity laser has been used to shock-compress liquid deuterium to pressures from 0.22 Mbar, near the upper end of gas-gun shock data, to 3.4Mbar. Using a variety of diagnostics, the density, pressure, and reflectivity of the shocked deuterium were determined, culminating in a knowledge of the behavior of hydrogen isotopes along the principal Hugoniot into the Mbar regime. It was found that hydrogen isotopes become highly compressible near 1 Mbar as a result of molecular dissociation and simultaneous ionization. Reflectivity measurements confirmed that deuterium transitions from an insulating state to a conducting phase at pressures near 0.5 Mbar on the Hugoniot and appears to do so in a continuous manner. At pressures above 0.5 Mbar, the measured reflectivity of the shocked deuterium is characteristic of a liquid metal. 相似文献
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The phonon dispersion curves of some liquid metals, viz. Na (Z = 1), Mg (Z = 2), Al (Z = 3) and Pb (Z = 4), have been computed using our model potential. The charged hard sphere (CHS) reference system is applied to describe
the structural information. Our model potential along with CHS reference system is capable of explaining the phonon dispersion
relation for monovalent, divalent, trivalent and tetravalent liquid metals. 相似文献