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Calculated Hugoniots and 293-K isotherms at pressures up to 1 TPa (10 Mbar) for the five reference metals Al, Cu, Ta, Mo, and W are reported using the classical mean-field approach where both the cold and the thermal parts of the Helmholtz free energy are derived entirely from the 0-K total energies and electronic density of states calculated with the full-potential linearized augmented plane wave method within the generalized gradient approximation to exchange correlational functional. Our approach permits efficient computation and invokes no empirical parameters. Both the experimental Hugoniots and 293-K isotherms are reproduced excellently. 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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Al、Cu、Ta高压熔化曲线的理论计算 总被引:1,自引:0,他引:1
由位错熔化理论和不同的静高压实验数据优化的体模量(B0)、剪切模量(G0)及它们对压力的一阶偏导数(B′0、G′0)值计算了Al、Cu、Ta的高压熔化曲线.理论计算的Al、Cu高压熔化曲线与静、动高压实验值较为吻合,Ta的理论高压熔化曲线与动高压实验结果一致,但与静高压实验结果相差较大. 相似文献
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Based on the first-principles all-electron full-potential augmented-plane-wave plus local orbital method, an equation of state (EOS) at OK for copper up to 10000 GPa (10^8 bar) is presented. Our recommended EOS is in good agreement with the available experimental data. Furthermore, the agreement between theoretical EOS of hcp and fcc lattices at extremely compressed condition sets the foundation of spherical atom models for high density and high temperate plasmas. 相似文献
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W.J. Nellis 《高压研究》2013,33(4):393-407
The method of deriving shock wave reduced isotherms (SWRIs) as pressure standards up to 150 GPa in a diamond anvil cell (DAC) is discussed. This method is applicable to any adiabatic compression. Hugoniots and isentropes can both be used as reference curves in this analysis. While only Hugoniots have been used to date, isentropes will probably be used in future to develop standards above ~ 200 GPa. Accuracies of SWRIs of Al, Cu, Ta, W, Au, Mo, and Pt are discussed. Hugoniots of diamond and MgO are in excellent agreement with their respective isotherms measured in DAC up to 140 and 55 GPa, respectively. The equation of state of a weakly compressible material is sensitive to pressure and weakly sensitive to temperature. Thus, strong crystals, such as diamond, MgO, and BN, can be used as pressure standards and temperature can be measured independently. Future experiments to improve accuracies of static-pressure standards are suggested. 相似文献
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《Solid State Communications》1987,64(11):1387-1388
Spherically averaged electron momentum densities (EMD) in Al, V and Cu metals have been calculated by using density functional theory in the phase-space approach. Compton profiles, J(q) and expectation values 〈pn〉 have been computed. These theoretical results show satisfactory agreement with the experimental data for Al, V and Cu. 相似文献
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W. B. Holzapfel 《高压研究》2013,33(2):81-126
Abstract The historical and theoretical background for the different mathematical forms commonly used to represent equations of state (EOS) for solids is reviewed and some criteria are discussed which allow to select some specific forms, which are not only convenient mathematical forms but bring out the physical meaning of the data. Some examples are discussed with emphasis on recent experimental and theoretical data including noble gas solids, simple metals and a few metals with special “anomalies” to illustrate the differences involved in the use of different EOS forms and to point out the specific physical reasons for differences in specific EOS forms. 相似文献
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G. Pottlacher 《高压研究》2013,33(1-2):450-453
Abstract Metal-samples are investigated as pan of a submicrosecond resistive pulse heating system up to temperatures of about 10.000 K and ambient pressures up to 0.5 GPa. The measuremnts allow the determination of such thermophysical properties as heat capacity and the mutual dependences between enthalpy, electrical resistivity, temperature and volume. Up to now investigations have been done on the following elements: C, W, Re, Ta, Mo, Nb, Fe, Ni, Cu, Pb, In, and Hg. From the investigations at elevated pressures an estimation of the critical point data of the metals lead and indium can be given. 相似文献
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金属状态方程对于探究金属及合金原子的相互作用中起到了至关重要的作用.本文使用第一原理计算了Ti, Nb, Al及其二元合金能量与原子间距关系(E-r关系),并使用得到的E-r关系计算了金属及合金的体弹性模量,结果与实验值吻合的很好.计算结果表明,使用不同的赝势,计算不同金属表现出不同的适用性;二元合金的E-r曲线处于对应合金化元素曲线之间;并且合金的E-r曲线会更靠近合金内含量较高的元素的E-r曲线;并发现合金E-r关系可通过组成合金的纯金属的E-r关系计算获得,且用该方法计算材料的体弹性模量与实验值非常符合. 相似文献
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《Solid State Communications》1986,60(9):719-721
Electron momentum densities (EMD) in Al, V, Cr and Cu metals have been estimated from the metallic electron charge densities by applying the procedure of Burkhardt, Konya and Coulson and March. The procedure has provided spherically averaged EMD from which corresponding Compton profiles, J(q) and 〈pn〉 expectation values have been computed. These theoretical results show satisfactory agreement with the experimental data for Al, V, Cr and Cu. 相似文献
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An isothermal equation of state (EOS) for solids, recently suggested by the authors in the realistic form, V/V0=f(P), with relative volume as the dependent and the pressure as the independent variable, was shown to have an advantage for some close-packed materials in that it allows B′∞=(∂Bs/∂P)s(P→∞) to be fitted, and this is where the usual standard equations fail. In the present study, our EOS is applied to a number of inorganic as well as organic solids, including alloys, glasses, rubbers and plastics; varying widely in their bonding and structural characteristics, as well as in their bulk modulus values. A very good agreement is observed between the data and fits. The results obtained are compared with those from two well-known equations, expressible in the realistic form, proposed by Murnaghan and Luban. Further, the results are also compared with those from the widely used two- and three-parameter EOSs, expressible in the unrealistic form only, P=f(V/V0), proposed by Birch—and also with those from the EOS model of Keane in which B′∞ is explicitly expressed as an equation of state parameter. The results obtained from our model compare well to these EOSs. Our EOS, in general, yields the smallest mean-squared deviations between data and fits. The values of B′∞calculated from our EOS are compared with those from Keane's model. Further, we have studied the variation of B′∞with temperature using the experimental isotherms of Mo and W at 10 different temperatures ranging from 100 to 1000 K, and observed that the values of B′∞ yielded by our model and that of Keane vary, as expected, within a narrow range. Furthermore, our EOS is applied to study the stability of the fit parameters with variation in the pressure ranges with reference to the isothermal compression data on Mo and W—and also to study the variation of isothermal bulk modulus with pressure, with reference to the ultrasonic data on NaCl and noted a very good agreement with experiment. In addition, our model is applied, with B0 and B′0 constrained to the theoretical values, to the five theoretical isotherms of MgO at 300, 500, 1000, 1500 and 2000 K obtained on the basis of a first principles approach—a good agreement is observed with the predictions, and the values of B′∞ inferred at different temperatures tend to converge to a constant value. 相似文献
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高压密封微波消解-ICP-AES法测定五种蒙药中无机元素 总被引:3,自引:0,他引:3
采用HNO3-HClO4消解体系分别对额日敦-乌日勒、德都红花七味丸、通拉嘎-5、乌珠目-7、给旺-9等五种蒙药样品进行高压微波消解制样,利用电感耦合等离子体原子发射光谱法(ICP-AES)同时测定了镁、铝、钙、铬、锰、铁、钴、镍、铜、锌、砷、硒、锶、钼、银、镉和铅等17种无机元素的含量。通过添加标准回收实验,回收率均在97.25%~106.35%之间,验证了分析数据的可靠性。所有元素测定结果的相对标准偏差均小于3.3%,具有良好的准确度和精密度。实验结果表明,其中常量元素Ca,Mg和Fe,Mn,Zn,Cu的含量较高,测定结果可为开发研制蒙药新制剂、研制蒙药的质量控制标准和提高蒙药药效提供理论依据。 相似文献
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The Hugoniot equations of state for shock compressed Cu, Ta, and Mo are calculated at pressures up to 4 TPa and then up to 10 TPa are obtained by extrapolation. The calculations are parameter-free in that the cold part of the Helmholtz free-energy is calculated using the first-principles full-potential linearized augmented plane wave method within the generalized gradient approximation, the thermal contribution to the Helmholtz free-energy due to the lattice oscillations is calculated using the recently developed classical mean-field potential approach, and that due to the thermal electrons is calculated using the one-dimensional numerical integration. The calculated results agree with the existing experimental values very well. 相似文献
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A. I. Bodretsova B. V. L'vov E. N. Pavlovskaya V. K. Prokof'ev 《Journal of Applied Spectroscopy》1965,2(2):62-67
Sealed hollow-cathode lamps containing the metals (Al, Bi, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mo, Ni, Pb, Sb, Sn, Ti, and Zn) have been examined for the relation of resonance-line strength and width to nature and pressure of the inert gas and also to discharge current. The relations are found to be generally applicable to hollow cathodes of most metals. The inherent noise level of the lamps does not exceed 0.1%. 相似文献