共查询到20条相似文献,搜索用时 62 毫秒
1.
V. D. Blank V. M. Levin V. M. Prokhorov S. G. Buga G. A. Dubitskii N. R. Serebryanaya 《Journal of Experimental and Theoretical Physics》1998,87(4):741-746
The elastic properties of C60 fullerite samples synthesized under pressure P=13.0 GPa at high temperatures were investigated using acoustic microscopy. The velocities of longitudinal (c
L=17–26 km/s) and transverse (c
T=7.2–9.6 km/s) elastic waves in the samples were measured. It was established that the longitudinal sound velocity of ultrahard
fullerites is higher than that of any other known solid. The bulk modulus of these ultrahard samples is higher than that of
diamond and reaches a value greater than 1 TPa. The high bulk modulus, the relatively large shear moduli, and the substantial
Poisson ratio indicate that the structure of the ultrahard fullerites is fundamentally different from that of diamond.
Zh. éksp. Teor. Fiz. 114, 1365–1374 (October 1998) 相似文献
2.
Fangfei Li Defang Duan Min Li Chunli Ma Qiliang Cui Tian Cui Qiang Zhou Xiaodong Li Yanchun Li Jing Liu Guangtian Zou 《Journal of Raman spectroscopy : JRS》2012,43(4):526-531
Single crystal Brillouin and Raman scattering measurements on NH3 in a diamond anvil cell have been performed under pressures up to 26 GPa at room temperature. The pressure dependencies of acoustic velocity, adiabatic elastic constants, and bulk moduli of ammonia from liquid to solid III and solid IV phase have been determined. All the nine elastic constants in orthorhombic structure phase IV were presented for the first time, each elastic constant grows monotonously with pressure and a crossover of the off‐diagonal moduli C12 and C13 was observed at around 12 GPa because of their different pressure derivative values. We also performed ab initio simulations to calculate the bulk elastic moduli for orthorhombic ammonia, the calculated bulk moduli agree well with experimental results. In Raman spectra the very weak bending modes ν2 and ν4 for orthorhombic ammonia are both observed at room temperature, a transition point near 12 GPa is also found from the pressure evolution of the Raman bands. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
3.
Single-crystal elasticity of the rhodochrosite at high pressure by Brillouin scattering spectroscopy
ABSTRACTThe sound velocity properties of single-crystal rhodochrosite (MnCO3) were determined up to 9.7?GPa at ambient temperature by Brillouin scattering spectroscopy. Six elastic constants were calculated by a genetic algorithm method using the Christoffel's equations at each pressure. The elastic constants increased linearly as a function of pressure and its pressure derivatives ?Cij/?P for C11, C33, C44, C12, C13, C14 were 5.86 (±0.36), 3.82 (±0.44), 2.06 (±0.39), 5.07 (±0.27), 5.34 (±0.44), 1.52 (±0.24), respectively. Based on the derived elastic constants of rhodochrosite, the aggregate adiabatic bulk and shear moduli (Ks and G) were calculated using the Voigt-Reuss-Hill averages and the linear fitting coefficients (?Ks/?P)T and (?G/?P)T were 5.05(±0.26) and 0.73(±0.05), respectively. The aggregate Vp of rhodochrosite increased clearly as a function of pressure and its pressure derivative ?Vp/?P was 7.99(±0.53)?×?10?2?km/(s?GPa), while the aggregate Vs increased slowly and ?Vs/?P was only 1.19(±0.12)?×?10?2?km/(s?GPa). The anisotropy factor for As of rhodochrosite increased from ~40% at 0.8?GPa to ~48% at 9.7?GPa, while Ap decreased from ~19% to ~16% at the corresponding pressure. 相似文献
4.
采用基于密度泛函理论的第一性原理赝势平面波方法,计算了(59Cr-41Ti)100-xVx(x=5,15,30,60,80,100)六种钒基储氢合金的晶格常数、弹性性质和电子态密度,计算结果与实验值符合较好.发现当x=60时的钒基合金具有较好弹性性质,杨氏模量为14930 GPa,切变模量为5442 GPa及体弹模量为19396 GPa.结合实验循环性能分析认为在吸放氢过程中合金已经发生塑性变形,弹性
关键词:
钒基固溶体
储氢合金材料
密度泛函理论
弹性性质 相似文献
5.
Abstract The electronics structure, the charge distribution and the total energy of hexagonal titaniumdiboride are calculated using non-local pseudopotentials in both the local density approximation (LDA) and the generalized gradient expansion approximation (GGA). In the LDA we obtain a = 3.023 Å, c = 3.166 Å and Bo = 271. GPa. For these quantities the GGA values are slightly lower and both compare well with experiment. We also determined selected elastic constants by fitting the total energies to a quadratic surface in the lattice parameters. Using strains that do not break the hexagonal symmetry we obtain C11 + C12 = 777.GPa, C13 = 83. GPa and C33 = 568. GPa. Again slightly lower values are obtained using the GGA. These values agree well with a recent experiment. 相似文献
6.
BaWO4-II has been synthesized at 5 GPa and 610°C. Its high pressure behavior was studied by in situ synchrotron X-ray diffraction measurements at room temperature up to 17 GPa. BaWO4-II retains its monoclinic structure. Bulk and axial moduli determined by fitting a third-order Birch–Murnaghan equation of state to lattice parameters are: K 0=86.2±1.9 GPa, K 0(a)=56.0±0.9 GPa, K 0(b)=85.3±2.4 GPa, and K 0(c)=146.1±3.2 GPa with a fixed K′=4. Analysis of axial compressible modulus shows that the a-axis is 2.61 times more compressible than the c-axis and 1.71 times more compressible than the b-axis. The beta angle decreases smoothly between room pressure and 17 GPa from 93.78° to 90.90°. 相似文献
7.
A. A. Stolbov A. G. Lyapin S. V. Popova V. V. Brazhkin E. L. Gromnitskaya O. V. Stal'GOROVA 《高压研究》2013,33(1-2):187-190
We present the systematic study of the elastic shear G and bulk B moduli in amorphous and crystalline metastable ternary solid solutions (GaSb)1?x Ge2x . It is found that the moduli of crystalline phases initially decrease with Ge concentration, falling down to minimum values at 20-30% Ge. The minimal values of elastic moduli for amorphous samples are observed at 50-60% Ge. Elastic softness of crystalline solid solutions is assumed to be related to the increase of chemical disorder and, consequently, of static (non-thermal) geometrical disorder in positions of atoms. An additional topological disorder in amorphous solid solutions leads to additional elastic softening. 相似文献
8.
N. P. Kobelev R. K. Nikolaev N. S. Sidorov Ya. M. Soifer 《Physics of the Solid State》2001,43(12):2344-2350
The attenuation and velocity of ultrasonic waves (at a frequency of ~4 MHz) along the 〈111〉 and 〈100〉 directions in solid C60 single-crystal samples are measured in the temperature range 100–300 K. The temperature dependences of the complete set of elastic constants for C60 fullerite are determined from the experimental data. It is shown that the specific features in the behavior of the elastic moduli near the orientational phase transition temperature are associated with different contributions of the relaxation processes to the effective elastic moduli. The activation volume and deformation potentials for the ground and excited states of the C60 low-temperature phase are evaluated from the results obtained in this work and the data available in the literature. 相似文献
9.
利用基于密度泛函理论的第一性原理平面波赝势方法 并结合准谐徳拜模型研究了NaCl结构的TiC在高压下的弹性性质、电子结构和热力学性质. 计算所得零温零压下的晶格常数、体弹模量及弹性常数与实验值符合得很好. 零温下弹性常数和弹性模量随压强增大而增大. 通过态密度和电荷密度的分析, Ti-C键随压强增大而增强. 运用准谐德拜模型, 成功计算了TiC在高温高压下的体弹模量、熵、热膨胀系数、徳拜温度、 Grüneisen参数和比热容. 结果表明压强对体弹模量、热膨胀系数和徳拜温度的影响大于温度对其的影响. 热容随着压强升高而减小, 在高温高压下, 热容接近Dulong-Petit极限. 相似文献
10.
The physical and mechanical properties of a C60 fullerene sample have been investigated under high pressure–high temperature conditions using a designer Diamond Anvil Cell. Electrical resistance measurements show evidence of C60 cage collapse at 20 GPa, which leads to the formation of an insulating phase at higher pressure. Energy dispersive X-ray diffraction (EDXD) data indicated that the characteristic fcc reflections gradually decrease in intensity and eventually disappear above 28 GPa. A C60 sample was laser-heated at a pressure of 35 GPa to a temperature of 1910±100 K and, subsequently, decompressed to ambient conditions. The photoluminescence spectra and the Raman spectrum of the pressure–temperature-treated sample were measured at a low temperature of 80 K. Raman peak at 1322.3 cm?1 with full-width half-maximum of 2.9 cm?1 was observed from the sample, which is attributed to the hexagonal diamond phase in the sample. The room temperature photoluminescence spectra showed a symmetric emission band centered in the red spectral range with a peak at 690 nm. The structural analysis of the pressure–temperature-processed C60 sample using EDXD method showed strong internal structure orientation and a phase close to hexagonal diamond. Mechanical properties such as hardness and Young’s modulus were measured by nanoindentation technique and the values were found to be 90±7 and 1215±50 GPa, respectively and these values are characteristic of sp3-bonded carbon materials. 相似文献
11.
The room temperature adiabatic elastic moduli of CaO were obtained using a pulse superposition technique to measure the ultrasonic velocities. The elastic moduli were found to be (in GPa) at 298 K.
c11 | c12 | c44 |
226.2 ±0.9 | 62.4 ±0.9 | 80.6 ±0.3 The pressure derivatives of the elastic moduli, which were measured at and below room temperature, decrease with decreasing temperature. The temperature derivatives of the elastic moduli were also obtained for several temperatures below room temperature. |