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《中国物理 B》2021,30(5):50701-050701
The phase transition behaviors of the shocked water are investigated by employing an optical transmittance in-situ detection system. Based on the light scattering theory and phase transformation kinetics, the phase transition mechanism of the water under multiple shocks is discussed. The experimental data indicate that the evolution of the transmittance of the shocked water can be broadly divided into three stages: relaxation stage, decline stage, and recovery stage. In the early stage of the phase transition, the new phase particles began to form around the quartz/window interface. It should be mentioned that the water/ice phase boundary seems to move toward the liquid region in one experiment of this work. Due to the new phase core being much smaller than the wavelength of the incident light, the transmittance of the sample within the relaxation stage remains steady. The decline stage can be divided into the rapid descent stage and the slow descent stage in this work, which is considered as the different growth rates of the new phase particle under different shock loadings. The recovery stage is attributed to the emergence of the new phase particles which are bigger than the critical value. However,the influence of the size growth and the population growth of the new phase particles on the transmittance restrict each other, which may be responsible for the phenomenon that the transmittance curve does not return to the initial level. 相似文献
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Vibrational properties and structural changes under pressure of a highly luminescent molecular organic crystal have been investigated by ultraviolet resonant Raman spectroscopy with a 244‐nm excitation. Resonant Raman modes of α‐perylene crystal up to 1GPa were followed under hydrostatic pressure in an anvil cell with a sapphire window transparent to ultraviolet light. Nonlinear evolution of intra‐molecular modes is induced by pressure. Abrupt shifts of Raman wavenumbers suggest structural and planar modifications of the molecules in the crystal. We interpret these shifts as a first‐order phase transition to a lower volume of unit cell. The luminescence of perylene crystal is gradually modified as a consequence of these structural changes. The present experimental setup allows investigating with Raman spectroscopy very luminescent molecules involved in chemical reactions and molecular organic crystals under relatively high pressure (up to 1GPa). Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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A. G. Gavriliuk I. A. Troyan A. G. Ivanova S. N. Aksenov S. S. Starchikov I. S. Lyubutin W. Morgenroth K. V. Glazyrin M. Mezouar 《JETP Letters》2017,105(11):733-738
The quantum heat generation, interaction force, and friction torque for two rotating spherical nanoparticles with the radius R are calculated. In contrast to a static case where an upper bound in the radiative heat transfer between two particles exists, the quantum heat generation for two rotating particles diverges at distances between particles d < d 0 = R(3/ε″(ω0))1/3 (where ε″(ω0) is the imaginary part of the dielectric function for the material of a particle at the resonance frequency ω0), when the rotation frequency coincides with poles in the excitation generation rate at Ω = 2ω0. These poles are due to the anomalous Doppler effect and the mutual polarization of particles and exist even in the presence of dissipation in particles. The anomalous heat generation is associated with the conversion of mechanical rotation energy into heat mediated by quantum friction. Similar singularities also exist for the interaction force and friction torque. The results can be of significant importance for biomedical applications. 相似文献
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The crystal structures of Si and Ge were studied by energy dispersive X-ray diffraction at room temperature and pressures up to 50 GPa. Si transforms to a primitive hexagonal (Si-V) structure around 16 GPa, to an intermediate phase Si-VI between 35 and 40 GPa, and to hcp (Si-VII) around 40 GPa. In contrast, Ge remains in the β-tin structure up to at least 51 GPa. The pseudopotential method reproduces these differences in the high-pressure behavior of Si and Ge. 相似文献
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Sugandha Dogra Jasveer Singh Himanshu Kumar Poswal S. M. Sharma A. K. Bandyopadhyay 《高压研究》2013,33(2):292-303
The present paper reports the results of in situ Raman studies carried out on nano-crystalline CeO2 up to a pressure of 35 GPa at room temperature. The material was characterized at ambient conditions using X-ray diffraction and Raman spectroscopy and was found to have a cubic structure. We observed the Raman peak at ambient at 465 cm?1, which is characteristic of the cubic structure of the material. The sample was pressurized using a diamond anvil cell using ruby fluorescence as the pressure monitor, and the phase evolution was tracked by Raman spectroscopy. With an increase in the applied pressure, the cubic band was seen to steadily shift to higher wavenumbers. However, we observed the appearance of a number of new peaks around a pressure of about 34.7 GPa. CeO2 was found to undergo a phase transition to an orthorhombic α -PbCl2-type structure at this pressure. With the release of the applied pressure, the observed peaks steadily shift to lower wavenumbers. On decompression, the high pressure phase existed down to a total release of pressure. 相似文献
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Yamamoto R Bell C Hikita Y Hwang HY Nakamura H Kimura T Wakabayashi Y 《Physical review letters》2011,107(3):036104
Using a surface x-ray diffraction technique, we investigated the atomic structure of two types of interfaces between LaAlO3 and SrTiO3, that is, p-type (SrO/AlO2) and n-type (TiO2/LaO) interfaces. Our results demonstrate that the SrTiO3 in the sample with the n-type interface has a large polarized region, while that with the p-type interface has a limited polarized region. In addition, atomic intermixing was observed to extend deeper into the SrTiO3 substrate at the n-type interface compared to the p type. These differences result in distinct degrees of band bending, which likely contributes to the striking contrast in electrical conductivity between the two types of interfaces. 相似文献
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G. N. Stepanov 《Physics of the Solid State》2014,56(8):1561-1568
The dependence of the unit cell volume of BaSnO3 on the pressure up to 15 GPa has been investigated and the constants of the Murnaghan equation of state B 0 = 178.39 ± 4.09 GPa and B′0 = 4.68 ± 0.56 have been obtained using the X-ray diffraction method. The change of the isomer shift (IS) in BaSnO3 with a variation in the pressure P has been examined using the gamma resonance method. This quantity is ?IS(P)/?P = ?(0.00474 ± 0.0002) mm s?1 GPa?1 or, taking into account the measurements of the unit cell parameter under pressure, ?IS/?L = 1.42 mm s?1Å?1, where L is the tin-oxygen distance. 相似文献
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The thermoelectric power (TEP) of cerium has been measured up to 6 GPa. The results have been interpreted using the theories developed by Blandin et. al. and Hirst. 相似文献
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Willmott PR Pauli SA Herger R Schlepütz CM Martoccia D Patterson BD Delley B Clarke R Kumah D Cionca C Yacoby Y 《Physical review letters》2007,99(15):155502
The complete atomic structure of a five-monolayer film of LaAlO3 on SrTiO3 has been determined for the first time by surface x-ray diffraction in conjunction with the coherent Bragg rod analysis phase-retrieval method and further structural refinement. Cationic mixing at the interface results in dilatory distortions and the formation of metallic La(1-x)SrxTiO3. By invoking electrostatic potential minimization, the ratio of Ti{4+}/Ti{3+} across the interface was determined, from which the lattice dilation could be quantitatively explained using ionic radii considerations. The correctness of this model is supported by density functional theory calculations. Thus, the formation of a quasi-two-dimensional electron gas in this system is explained, based on structural considerations. 相似文献
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H. Olijnyk 《高压研究》2013,33(1-2):461-464
Abstract Measurements of k ≈ 0 optical phonons by Raman scattering are reported for Zn metal and for metallic high pressure phases of Si and Ge up to 50 GPa. Mode Griineisen parameters are determined and the experimental results are compared with theoretical results. 相似文献
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The static equation of state (EOS) of tantalum (Ta) is determined by in situ energy-dispersive synchrotron powder x-ray diffraction in a diamond anvil cell (DAC) up to 133GPa. The body-centered-cubic (bcc) phase of Ta is found to be stable over the entire pressure range investigated. The bulk moduli and its first pressure derivative of Ta are constrained by fitting the determined pressure-volume data to Vinet form EOS: B0 =192.65±(3.08)GPa and B'0 =3.58±(0.11). For the sake of avoiding the affect of non-hydrostatic stress, argon is used as a pressure media. A careful checking of the stress state of the sample is presented simultaneously. 相似文献
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The high-mobility conducting interface (CI) between LaAlO3 (LAO) and SrTiO3 (STO) has revealed many fascinating phenomena, including exotic magnetism and superconductivity. But, the formation mechanism of the CI has not been conclusively explained. Here, using in situ angle-resolved photoemission spectroscopy, we elucidated the mechanisms for the CI formation. In as-grown samples, we observed a built-in potential (Vbi) proportional to the polar LAO thickness starting from the first unit cell (UC) with CI formation appearing above 3 UCs. However, we found that the Vbi is removed by synchrotron ultraviolet (UV)-irradiation; The built-in potential is recovered by oxygen gas (O2(g))-exposure. Furthermore, after UV-irradiation, the CI appears even below 3UC of LAO. Our results demonstrate not only the Vbi-driven CI formation in as-grown LAO/STO, but also a new route to control of the interface state by UV lithographic patterning or other surface modification. 相似文献
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V. D. Urlin M. A. Mochalov O. L. Mikhailova 《Journal of Experimental and Theoretical Physics》1997,84(6):1145-1148
The compressibility of liquid argon up to pressures ∼500 GPa has been investigated experimentally. The argon was compressed
by a cylindrical shell accelerated by the detonation products of an explosive. The density was recorded by the gamma-graphic
method and the pressure was determined from the gas-dynamic calculations. Comparing the experimental and computational results
showed that the compression process studied is isentropic to a quite high degree. The compression of liquid argon up to a
density of 7.3 g/cm3 did not show any clear anomalies associated with a structural transition or metallization.
Zh. éksp. Teor. Fiz. 111, 2099–2105 (June 1997) 相似文献
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Abstract Copper oxide has been studied at high pressure up to 50 GPa. A monoclinic structure was compatible with the measurements at all pressures, and no phase change was observed. A bulk modulus, B0, = 98 GPa, and its pressure derivative B′0 = 5.6 was obtained. 相似文献
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Abstract By means of a four-point resistivity method the critical temperature (Tc) of the tetragonal high temperature super-conductor CaLaBaCu3Ox was studied for pressures up to 9 GPa. The pressure dependence of Tc is small and negative, dTc/dp = - 0.77 K/GPa, and agrees with the general trend observed in previous data. 相似文献
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Gold powder is compressed non-hydrostatically up to 127 GPa in a diamond anvil cell(DAC),and its angle dispersive X-ray diffraction patterns are recorded.The compressive strength of gold is investigated in a framework of the lattice strain theory by the line shift analysis.The result shows that the compressive strength of gold increases continuously with the pressure up to 106 GPa and reaches 2.8 GPa at the highest experimental pressure(127 GPa) achieved in our study.This result is in good agreement with our previous experimental result in a relevant pressure range.The compressive strength of gold may be the major source of the error in the equation-of-state measurement in various pressure environments. 相似文献
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在同一理论框架内,基于冲击Hugoniot和热力学参数计算了Al、Cu、W、 Au、Pt、Ta、Ag、Mo、Ni、Co和Zn的300 K等温压缩线,并结合现有静高压实验数据,在160 GPa压力范围内重新标定了红宝石压标。所采用的两种红宝石压标形式的标定结果分别为A=1 923.4 GPa、B=9.75和m=1 889.0 GPa、n=5.48,两者具有非常好的自洽性,200 GPa压力范围内确定的压力偏差小于2.1 GPa。基于提出的红宝石压标,重新计算了3组Au等温压缩实验的加载压力。固定等温体模量为167 GPa,重算的实验数据拟合至Vinet物态方程所得等温体模量对压力的一阶偏导为5.95,与超声实验数据非常吻合。 相似文献
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The electronic structure of interfaces between LaAlO3 and SrTiO3 is studied using local spin density approximation (LSDA) with intra-atomic Coulomb repulsion (LSDA + U). We find that the nature of the interface metallic states is strongly affected by the type of the structure (sandwich or bilayer) and by the termination surface of LaAlO3. In all structures the atomic relaxation plays a crucial role in the electronic properties of the system. While in sandwiches the structural relaxation produces a significant polarization in SrTiO3 and a splitting of Ti 3dxy orbitals, in AlO2-terminated bilayers the relaxation occurs primarily in LaAlO3 and results in an insulator-metal transition which has been observed experimentally with increasing thickness of the LaAlO3 layer. 相似文献