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1.
Initiation of a self-sustained volume discharge in CO2-containing gaseous mixtures kept under a pressure of up to 10 atm with the aim of amplifying picosecond IR pulses is considered.
Experimental electricdischarge and optical characteristics of a wide-aperture high-pressure CO2 amplifier are presented. The feasibility of designing terawatt laser equipment with a master oscillator and preamplifier
is discussed. 相似文献
2.
Rong Yang Bin Tang Tao Gao Bing Yun Ao 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(8):145
The structural, magnetic, electronic, vibrational, thermodynamic and elastic properties of plutonium sesquicarbide (Pu2C3) are investigated based on density functional theory. The use of the Hubbard term to describe the 5f electrons of plutonium is discussed according the lattice parameters and magnetism. The calculated lattice constants, magnetism and density of states agree well with the experimental data or other theoretical calculations. The Pu-C bonds of Pu2C3 have a mixture of covalent character and ionic character, while covalent character is stronger than ionic character. The phonon frequencies and the assignment of infrared-active, Raman-active and silent modes at Γ point are obtained. Furthermore, the enthalpy difference H-H298, entropy S, heat capacity and linear thermal expansion coefficient α of Pu2C3 have been calculated and compared with the available data. Lastly, the calculated elastic properties predict that Pu2C3 is ductile metal. In addition, the effect of spin-orbit coupling on the structural, magnetic, and electronic properties of Pu2C3 has been discussed. We hope that our results can provide a useful reference for further theoretical and experimental research on Pu2C3. 相似文献
3.
V. M. Gremyachkin V. A. Dudkin V. B. Rukhin 《Russian Journal of Physical Chemistry B, Focus on Physics》2008,2(4):543-546
The rates of graphite gasification in interaction with high-temperature gas flows were compared. Carbon dioxide and a mixture of water vapor and argon taken in a 1:1 molar ratio were used as reagents. The reactor was a tube furnace; its temperature was varied from 1250 to 1400 K. The rates of graphite gasification in CO2 and water vapor-argon mixture flows were approximately equal at 1250–1300 K, whereas, at 1350–1400 K, the water vapor-argon mixture exhibited higher reactivity than CO2. The data obtained were approximated by Arrhenius dependences; the activation energy was found to be 153 kJ/mol for CO2 and 248 kJ/mol for H2O-Ar. 相似文献
4.
The crystal structure and magnetic properties of the (La0.3Sr0.7)0.5Ca0.5FeO3 solid solution with a perovskite structure have been investigated. The solid solution has been synthesized according to the
high-pressure technique. The unit cell parameters have been refined using the Rietveld full-profile analysis under the assumption
of the single-phase crystalline state and the two-phase model corresponding to the parent compositions. It follows from the
calculations that the best agreement between the experimental data and the theoretical curve is observed for the two-phase
model. The measurement of the magnetic properties also indicates the coexistence of two magnetic phases. 相似文献
5.
N. V. Melnikova N. I. Kadyrova A. V. Tebenkov I. S. Ustinova Yu. G. Zaynulin A. N. Babushkin 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(8):1121-1123
The results from experimental investigations on the effect of high pressures (10–50 GPa) on the electrical properties and
magnetoresistance of the perovskite-like high-pressure state of CaCoCu2V4O12 are presented. The pressure ranges of substantial changes in the behavior of electrical characteristics are determined. 相似文献
6.
Jinxuan Han A. Kh. Bogomolov E. Yu. Makarova Zhaozhong Yang Yanjun Lu Jianbao Han Xiaogang Li 《Russian Journal of Physical Chemistry B, Focus on Physics》2018,12(4):714-724
Based on the chemical model of coal, slit micropores with different pore sizes are established and structures are optimized in the software of materials studio. As the temperature rises, absolute adsorption capacities of H2O are slightly affected, while absolute adsorption capacities of CO2 and CH4 gradually decrease. As the fugacity rises, excess adsorption curves of CO2 experience increase-decrease-gentle three stages, while the curves of CH4 gradually decrease. With the increase of pore size, adsorption capacities of H2O increase, while adsorption capacities of CO2 and CH4 gradually decrease. H2O firstly adsorbs on the oxygen-containing functional group, so the walls of pore are the preferential area for H2O, while CO2 and CH4 choose to adsorb on–C–C–, therefore the walls are the primary area for CO2 and CH4. Strong potential in micropores and hydrogen bond among water molecules will promote the water adsorption, while the adsorptions of CO2 and CH4 are only induced by the Van der Waals interaction, but the difference between adsorption density and bulk density of CO2 and CH4 decides the change of excess adsorption capacity. 相似文献
7.
B. A. Voronin N. N. Lavrentieva S. S. Voronina E. A. Shevchenko A. A. Fedorova 《Optics and Spectroscopy》2018,124(5):618-623
Carbon-dioxide-broadening coefficients and self-broadening coefficients of lines of the main isotopic modification of Н2S are estimated on the basis of literature data. The J′-dependences of the above line-profile parameters of the hydrogen-sulfide molecule are examined. In the case of CO2 broadening, the half-widths of lines are calculated by a semiempirical method based on a parametric modification of the impact semiclassical model; the model parameters were determined from the fit to experimental data. 相似文献
8.
The structural parameters, density of states, electronic band structure, charge density, and optical properties of orthorhombic SrBi2Ta2O9 have been investigated using the plane-wave ultrasoft pseudopotential technique based on the first-principle density functional theory (DFT). The calculated structural parameters were in agreement with the previous theoretical and experimental data. The band structure showed an indirect (S to Γ) band gap with 2.071 eV. The chemical bonding along with population analysis has been studied. The complex dielectric function, refractive index, and extinction coefficient were calculated to understand the optical properties of this compound, which showed an optical anisotropy in the components of polarization directions (100), (010), and (001). 相似文献
9.
The structural properties of Na2RuO3 under pressure are studied using density functional theory within the nonmagnetic generalized gradient approximation (GGA). We found that one may expect a structural transition at ~3 GPa. This structure at the high-pressure phase is exactly the same as the low-temperature structure of Li2RuO3 (at ambient pressure) and is characterized by the P21/m space group. Ru ions form dimers in this phase and one may expect strong modification of the electronic and magnetic properties in Na2RuO3 at pressure higher than 3 GPa. 相似文献
10.
Lingping Xiao Xiaobin Li Xue Yang 《The European Physical Journal B - Condensed Matter and Complex Systems》2018,91(5):85
We report first-principles studies the structural, electronic, and optical properties of the Fe2SiO4 fayalite in orthorhombic structure, including pressure dependence of structural parameters, band structures, density of states, and optical constants up to 30 GPa. The calculated results indicate that the linear compressibility along b axis is significantly higher than a and c axes, which is in agreement with earlier work. Meanwhile, the pressure dependence of the electronic band structure, density of states and partial density of states of Fe2SiO4 fayalite up to 30 GPa were presented. Moreover, the evolution of the dielectric function, absorption coefficient (α(ω)), reflectivity (R(ω)), and the real part of the refractive index (n(ω)) at high pressure are also presented. 相似文献
11.
Ab initio calculations of the crystal structure and fundamental vibrations of vanadium pyrochlores Lu2V2O7 and Y2V2O7 are performed. The calculations are performed in the framework of the density functional theory (DFT) with the use of hybrid functionals. The ions involved in the vibrations are determined by the isotope substitution method. Values of the isotropic exchange interaction constant were calculated. Theoretical results for the crystal structure parameters, the vibrational frequencies, and the isotropic exchange interaction parameter are compared with the experimental data. 相似文献
12.
S. Ağduk G. Gökoğlu 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,79(4):509-514
We present the results of ab initio calculations of lattice dynamics and the second order
elastic stiffness constants of nickel-based magnetic shape memory alloy Ni2MnIn in
stoichiometric composition. The plane wave basis sets and pseudopotential
method within spin-polarized generalized gradient approximation (σ-GGA) scheme of the density functional theory (DFT) is applied. Elastic
constants are calculated by tetragonal and monoclinic isochoric strains
on cubic L21 structure. The calculated elastic constants
agree very well with the recent ultrasonic experimental data. Phonon dispersion spectra are investigated within linear response
technique
of the density functional perturbation theory (DFPT). A vibrational anomaly is observed in phonon spectra at the transverse
acoustic mode (TA2) in [ζ
ζ0]
direction at wavevector ζ = 0.3 as an indication of the structural instability of the system to shear deformation. This anomaly is also verified by
the
low shear modulus and large elastic anisotropy ratio. Phonon dispersion curves are in excellent agreement with the results
of recent neutron diffraction experiments. 相似文献
13.
Synchrotron small angle X-ray scattering (SAXS) was performed to investigate the effect of dissolved CO2 in toluene on the conformation of polystyrene (PS) in the solution. It has been found that the second virial coefficientA
2 and the radius of gyrationR
g decrease with the increasing antisolvent CO2 pressure. The scattering intensity of PS chain followedI(h) ∞h
−α under different antisolvent pressures (0, 0.6, 1.5, 2.4, 3.3, and 4.2 MPa), suggesting that the PS chain has self-similar
structure behavior or a fractal structure in the presence of antisolvent CO2. All this reveals a large effect of antisolvent pressure or the solubility of CO2 in the solution on PS structure. The fractal dimensions increase with the increasing antisolvent pressure, indicating that
the polymer chain changes from a swollen coil into a rather dense globule in the course of adding antisolvent CO2. 相似文献
14.
Zhi Liang 《Molecular physics》2013,111(10):1285-1295
The density, isochoric heat capacity, shear viscosity and thermal conductivity of CO2 gas in the pressure range of 1–50 atm and 300 K are calculated based on a five-centre potential model obtained from ab initio calculations of the intermolecular potential of a CO2 dimer. The quantum effects of the intramolecular motion are included in a model by the Monte Carlo (MC) Method. Without using any experimental data, the present model achieves excellent agreements between the calculated thermophysical properties and experimental data for all simulated CO2 densities except the highest one at 135 kg/m3 (3 mol/L). The contributions of potential to the thermophysical properties of the moderate dense CO2 gas and their dependence on density are investigated in detail. 相似文献
15.
A.?A.?Kvasov Yu.?F.?Markov E.?M.?Roginski? M.?B.?Smirnov 《Physics of the Solid State》2009,51(7):1426-1430
Thefrequency dispersion curve of acoustic and optical phonons are calculated and constructed, and the density of states of the phonon spectrum is obtained for Hg2Cl2 crystals. The influence of the hydrostatic pressure on the frequencies of acoustic and optical phonons and their dispersion is analyzed theoretically. It is revealed that an increase in the pressure leads to a considerable softening of the slowest acoustic TA branch (soft mode) at the X point of the Brillouin zone boundary. This behavior is consistent with the phenomenological Landau theory and correlate with experiments. 相似文献
16.
The crystal structure and phonon spectrum of PrFe3(BO3)4 are ab initio calculated in the context of the density functional theory. The ion coordinates in the unit cell of a crystal and the lattice parameters are evaluated from the calculations. The types and frequencies of the fundamental vibrations, as well as the line intensities of the IR spectrum, are determined. The elastic constants of the crystal are calculated. A “seed” frequency of the vibration strongly interacting with the electron excitation on the praseodymium ion is obtained for low-frequency A2 mode. The calculated results are in agreement with the known experimental data. 相似文献
17.
A. Bouhemadou Y. Al-Douri R. Khenata K. Haddadi 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,71(2):185-194
We have investigated the structural, elastic, electronic, optical and
thermal properties of c-SiGe2N4 by using the ultrasoft
pseudopotential density functional method within the generalized gradient
approximation. The calculated structural parameters, including the lattice
constant, the internal free parameter, the bulk modulus and its pressure
derivative are in agreement with the available data. The independent elastic
constants and their pressure dependence, calculated using the static finite
strain technique, satisfy the requirement of mechanical stability,
indicating that c-SiGe2N4 compound could be stable. We derive the
shear modulus, Young’s modulus, Poisson’s ratio and Lamé’s coefficients
for ideal polycrystalline c-SiGe2N4 aggregate in the framework of
the Voigt-Reuss-Hill approximation. We estimate the Debye temperature of
this compound from the average sound velocity. Band structure, density of
states, Mulliken charge populations and pressure coefficients of energy band
gaps are investigated. Furthermore, in order to understand the optical
properties of c-SiGe2N4, the dielectric function, refractive index,
extinction coefficient, optical reflectivity and electron energy loss are
calculated for radiation up to 40 eV. Thermal effects on some macroscopic
properties of c-SiGe2N4 are predicted using the quasi-harmonic
Debye model in which the lattice vibrations are taken into account. We have
obtained successfully the variations of the primitive cell volume, volume
expansion coefficient, heat capacities and Debye temperature with pressure
and temperature in the ranges of 0–40 GPa and 0–2000 K. For the first
time, the numerical estimates of the elastic constants and related
parameters, and the thermal properties are performed for
c-SiGe2N4. 相似文献
18.
The relationship between structure and pressure for MgSiN2 has been simulated using a density functional approximation within the local density approximation. The low-pressure (LP-) phase of MgSiN2 with an orthorhombic structure transforms to a high-pressure (HP-) modification with a CsICl2-type structure at a pressure of about 16.5 GPa. HP-MgSiN2 , in which both Mg and Si are octahedrally coordinated by N, has a bulk modulus of about 238 GPa, much higher than that of the LP-modification (about 182 GPa) with tetrahedrally coordinated metal atoms. HP-MgSiN2 is a wide-gap semiconductor with an indirect energy gap of about 4.3 eV, similar to that of LP-MgSiN2. The direct gap at is about 5.8 eV. PACS 71.15.Mb; 61.50.Ks; 61.50.Ah 相似文献
19.
A. Bouhemadou R. Khenata M. Chegaar 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(3):209-215
Using first-principles density functional calculations, the effect of high
pressures, up to 20 GPa, on the structural and elastic properties of
Zr2AlX and Ti2AlX, with X = C and N, were studied by means of the
pseudo-potential plane-waves method. Calculations were performed within the
local density approximation to the exchange-correlation approximation
energy. The lattice constants and the internal parameters are in agreement
with the available results. The elastic constants and their pressure
dependence are calculated using the static finite strain technique. We
derived the bulk and shear moduli, Young's moduli and Poisson's ratio for
ideal polycrystalline Zr2AlX and Ti2AlX aggregates. We estimated
the Debye temperature of Zr2AlX and Ti2AlX from the average sound
velocity. This is the first quantitative theoretical prediction of the
elastic properties of Zr2AlC, Zr2AlN and Ti2AlN compounds,
and it still awaits experimental confirmation. 相似文献
20.
J.-E.?J?rgensen T. C.?Hansen 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,78(4):411-415
The crystal structure of BaFe2As2 was studied
by high-pressure neutron powder diffraction in the pressure range from
ambient to 6.5 GPa as well as in the temperature range from 12 K to 293 K at
4.4 GPa and no pressure or temperature induced phase changes were observed.
The compression mechanism of BaFe2As2 was found to be anisotropic
as the a- and c-axes are reduced by 2.49 and 3.66%, respectively at 6.5
GPa. Within the FeAs layers the Fe-As and Fe-Fe bonds decrease by 2.49 and
3.66%, respectively. The Ba-As distance decreases by 3.70% while the
As-As inter-atomic distance along the c-axis exhibits a complex pressure
dependence. The bulk modulus B
0 and its pressure derivative B
0' were
determined to be B
0 = 59(2) GPa and B
0' = 6.1(7) at ambient
temperature. 相似文献