We study the influence of the model parameters on the phase transitions, the equation of state （EOS）, and the corresponding mass-radius relations in the interior of neutron stars. The numerical analysis shows that t...We study the influence of the model parameters on the phase transitions, the equation of state （EOS）, and the corresponding mass-radius relations in the interior of neutron stars. The numerical analysis shows that the coupling constants of hyperons have a slight influence on the phase transitions and EOS, but an obvious influence on the particle fractions, while the bag constant B and coupling constant g have an important influence on the phase transitions, the EOS, and the mass-radius relations. We find that both the bag constant B and coupling constant g play the same role in the description of the interactions between quarks of hybrid stars. The maximum mass calculated by using the bag constant determined with experimental data （ranging from 175 to 200 MeV） falls in the interval of 1.4 ～1.7 solar mass. The corresponding radius is between 9.3 and 12 km. These results are in agreement with observed values of neutron stars. The possibility of the existence of a third family is discussed. The detection of a third family may provide a signature for a phase transition inside neutron stars.展开更多
The ramp wave compression experiments of iron with different thicknesses were performed on the magnetically driven ramp loading device CQ-4.Numerical simulations of this process were done with Hayes multi-phase equati...The ramp wave compression experiments of iron with different thicknesses were performed on the magnetically driven ramp loading device CQ-4.Numerical simulations of this process were done with Hayes multi-phase equation of state (H-MEOS) and dynamic equations of phase transition.The calculated results of H-MEOS are in good agreement with those of shock phase transition,but are different from those under ramp wave compression.The reason for this is that the bulk modulus of the material in the Hayes model and the wave velocity are considered constant.Shock compression is a jump from the initial state to the final state,and the sound speed is related to the slope of the Rayleigh line.However,ramp compression is a continuous process,and the bulk modulus is no longer a constant but a function of pressure and temperature.Based on Mumaghan equation of state,the first-order correction of the bulk modulus on pressure in the Hayes model was carried out.The numerical results of the corrected H-MEOS agree well with those of pure iron in both ramp and shock compression phase transition experiments.The calculated results show that the relaxation time of iron is about 30 ns and the phase transition pressure is about 13 GPa.There are obvious differences between the isentropic and adiabatic process in terms of pressure-specific volume and temperature-pressure.The fluctuation of the sound speed after 13 GPa is caused by the phase transition.展开更多
In this article we state that the compression factor of the Redlich-Kwong Equation Of State （EOS） is smaller than that of van der Waals EOS. The Redlich-Kwong EOS is in better agreement with experimental data on coe...In this article we state that the compression factor of the Redlich-Kwong Equation Of State （EOS） is smaller than that of van der Waals EOS. The Redlich-Kwong EOS is in better agreement with experimental data on coexistence curves at the critical point than the van der Waals EOS. We implement the Redlich-Kwong EOS in the Lattice Boltzmann Method （LBM） simulations via a pseudo-potential approach. We propose a new force, which can obtain computational stationary and reach larger density ratio. As a result, multi-phase flows with large density ratio （up to 1012 in the stationary case） can be simulated. We perform four numerical simulations, which are respectively related to single liquid droplet, vapor-liquid separation, surface tension and liquid coalescence of two droplets.展开更多
We study the hadron-quark phase transition in the interior of neutron stars, and examine the influence of the nuclear equation of state on the phase transition and neutron star properties. The relativistic mean field ...We study the hadron-quark phase transition in the interior of neutron stars, and examine the influence of the nuclear equation of state on the phase transition and neutron star properties. The relativistic mean field theory with several parameter sets is used to construct the nuclear equation of state, while the Nambu-Jona-Lasinio model is used for the description of the deconfined quark phase. Our results show that a harder nuclear equation of state leads to an earlier onset of a mixed phase of hadronic and quark matter. We find that a massive neutron star possesses a mixed phase core, but it is not dense enough to possess a pure quark core.展开更多
The structural stability of manganese titanate MnTiO3 at high pressure was investigated by X-ray diffraction and Raman spectroscopy with diamond anvil cells. Ilmenite-type MnTiO3 is stable at least to 26.6 GPa, and li...The structural stability of manganese titanate MnTiO3 at high pressure was investigated by X-ray diffraction and Raman spectroscopy with diamond anvil cells. Ilmenite-type MnTiO3 is stable at least to 26.6 GPa, and lithium niobate type MnTiO3 reversibly transforms at room temperature to perovskite at 2.0 GPa. Bulk moduli （K300） of ilmenite, lithium niobate and perovskite are 174（4） GPa, 179 （8） GPa, and 208（5） GPa, respectively （at fixed first pressure derivative K＇ = 4）. The Griineisen parameter T has been estimated to be 1.28 for ilmenite and 1.75 for perovskite. In ilmenite phase, TiO6 octahedra become more regular with increasing pressure. In perovskite phase structural distortion increases with pressure increase.展开更多
Properties of solid C<sub>60</sub> at atmospheric pressure have been widely studied since solid C<sub>60</sub> wasdiscovered. In recent years, the crystal structure, electrical and optical prop...Properties of solid C<sub>60</sub> at atmospheric pressure have been widely studied since solid C<sub>60</sub> wasdiscovered. In recent years, the crystal structure, electrical and optical properties of solidC<sub>60</sub> at high pressure have been studied, and some new interesting phenomena observed. Thehigh-pressure X-ray diffracion and electrical resistance measurements showed that solid C<sub>60</sub> hasa phase transition at about 15-22GPa. Recent studies still indicated that solid C<sub>60</sub> has展开更多
Ⅰ. INTRODUCTIONAlH<sub>3</sub> is a hydride with higher hydrogen content. Thus, many scientists are very interested in it. In recent years, properties of AlH<sub>3</sub> have been much studied...Ⅰ. INTRODUCTIONAlH<sub>3</sub> is a hydride with higher hydrogen content. Thus, many scientists are very interested in it. In recent years, properties of AlH<sub>3</sub> have been much studied under the atmospheric pressure, but less under high pressure. Our purposes in studying the properties of hydrides under high pressure are as follows:展开更多
This study presents high pressure phase transitions and equation of states of cerium under pressures up to 51 GPa at room temperature. The angle-dispersive x-ray diffraction experiments are carried out using a high en...This study presents high pressure phase transitions and equation of states of cerium under pressures up to 51 GPa at room temperature. The angle-dispersive x-ray diffraction experiments are carried out using a high energy synchrotron x-ray source. The bulk moduli of high pressure phases of cerium are calculated using the Birch-Mumaghan equation. We discuss and correct several previous controversial conclusions, which are caused by the measurement accuracy or personal explanation. The c/a axial ratio of e-Ce has a maximum value at about 29 GPa, i.e., c/a ≈ 1.690.展开更多
The deconfinement phase transition from ha-dronic matter to quark matter in the interior of compact stars is investigated. The hadronic phase is described in the framework of relativistic mean-field (RMF) theory, when...The deconfinement phase transition from ha-dronic matter to quark matter in the interior of compact stars is investigated. The hadronic phase is described in the framework of relativistic mean-field (RMF) theory, when also the scalar-isovector δ-meson effective field is taken into account. The MIT bag model for describing a quark phase is used. The changes of the pa-rameters of phase transition caused by the pre- sence of δ-meson field are investigated. Finally, alterations in the integral and structure para-meters of hybrid stars due to deconfinement phase transitions are discussed.展开更多
We perform a systematic study of elliptic flow（v2） in Au＋Au collisions at √^SNN = 5 GeV by using a microscopic transport model, JAM. The centrality, pseudorapidity, transverse momentum and beam energy dependence o...We perform a systematic study of elliptic flow（v2） in Au＋Au collisions at √^SNN = 5 GeV by using a microscopic transport model, JAM. The centrality, pseudorapidity, transverse momentum and beam energy dependence of v2 for charged as well as identified hadrons are studied. We investigate the effects of both the hadronic mean-field and the softening of equation of state（EoS） on elliptic flow. The softening of the EoS is realized by imposing attractive orbits in two body scattering, which can reduce the pressure of the system. We found that the softening of the EoS leads to the enhancement of v2, while the hadronic mean-field suppresses v2 relative to the cascade mode. It indicates that elliptic flow at high baryon density regions is highly sensitive to the EoS and the enhancement of v2 may probe the signature of a first-order phase transition in heavy-ion collisions at beam energies of a strong baryon stopping region.展开更多
Hydride has a very wide field. Properties of hydrides have been much studied at atmospheric pressure, and hydrides have been extensively applied in research and production. However, their properties at high pressure h...Hydride has a very wide field. Properties of hydrides have been much studied at atmospheric pressure, and hydrides have been extensively applied in research and production. However, their properties at high pressure have been less studied. In recent years, there has been considerable interest in studying properties and metallic transitions of hydrides at high pressure. Straaten et al.have studied the properties of HI at high pressure and discovered an insulator-to-metal transition in HI at pressures of 42.展开更多
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10047001 and 10275029, the State Key Basic Reserch Development Program under Grant No, G2000-0774-07, and the CAS Knowledge Innovation Project under Grant No. KJCX2-N11
文摘We study the influence of the model parameters on the phase transitions, the equation of state （EOS）, and the corresponding mass-radius relations in the interior of neutron stars. The numerical analysis shows that the coupling constants of hyperons have a slight influence on the phase transitions and EOS, but an obvious influence on the particle fractions, while the bag constant B and coupling constant g have an important influence on the phase transitions, the EOS, and the mass-radius relations. We find that both the bag constant B and coupling constant g play the same role in the description of the interactions between quarks of hybrid stars. The maximum mass calculated by using the bag constant determined with experimental data （ranging from 175 to 200 MeV） falls in the interval of 1.4 ～1.7 solar mass. The corresponding radius is between 9.3 and 12 km. These results are in agreement with observed values of neutron stars. The possibility of the existence of a third family is discussed. The detection of a third family may provide a signature for a phase transition inside neutron stars.
基金the National Natural Science Foundation of China(Grant 11327803)the project of Youth Innovation of Science and Technology of Sichuan Province(Grant 2016TD0022)the National Challenging Plan(Grant JCKY2016212A501).
文摘The ramp wave compression experiments of iron with different thicknesses were performed on the magnetically driven ramp loading device CQ-4.Numerical simulations of this process were done with Hayes multi-phase equation of state (H-MEOS) and dynamic equations of phase transition.The calculated results of H-MEOS are in good agreement with those of shock phase transition,but are different from those under ramp wave compression.The reason for this is that the bulk modulus of the material in the Hayes model and the wave velocity are considered constant.Shock compression is a jump from the initial state to the final state,and the sound speed is related to the slope of the Rayleigh line.However,ramp compression is a continuous process,and the bulk modulus is no longer a constant but a function of pressure and temperature.Based on Mumaghan equation of state,the first-order correction of the bulk modulus on pressure in the Hayes model was carried out.The numerical results of the corrected H-MEOS agree well with those of pure iron in both ramp and shock compression phase transition experiments.The calculated results show that the relaxation time of iron is about 30 ns and the phase transition pressure is about 13 GPa.There are obvious differences between the isentropic and adiabatic process in terms of pressure-specific volume and temperature-pressure.The fluctuation of the sound speed after 13 GPa is caused by the phase transition.
基金supported by the Ministry of Education in China(Grant No. IRT0844)the Shanghai Science and Technology Commission Project of Excellent Academic Leaders (Grant No.11XD1402300)
文摘In this article we state that the compression factor of the Redlich-Kwong Equation Of State （EOS） is smaller than that of van der Waals EOS. The Redlich-Kwong EOS is in better agreement with experimental data on coexistence curves at the critical point than the van der Waals EOS. We implement the Redlich-Kwong EOS in the Lattice Boltzmann Method （LBM） simulations via a pseudo-potential approach. We propose a new force, which can obtain computational stationary and reach larger density ratio. As a result, multi-phase flows with large density ratio （up to 1012 in the stationary case） can be simulated. We perform four numerical simulations, which are respectively related to single liquid droplet, vapor-liquid separation, surface tension and liquid coalescence of two droplets.
基金Supported by National Natural Science Foundation of China(10675064)Specialized Research Fund for the Doctoral Program of Higher Education(20040055010)
文摘We study the hadron-quark phase transition in the interior of neutron stars, and examine the influence of the nuclear equation of state on the phase transition and neutron star properties. The relativistic mean field theory with several parameter sets is used to construct the nuclear equation of state, while the Nambu-Jona-Lasinio model is used for the description of the deconfined quark phase. Our results show that a harder nuclear equation of state leads to an earlier onset of a mixed phase of hadronic and quark matter. We find that a massive neutron star possesses a mixed phase core, but it is not dense enough to possess a pure quark core.
基金an Alexander von Humboldt Fellowship in Germany and S.Qin acknowledges the financial support of the National Natural Science Foundation of China(Grant No. 40972029)
文摘The structural stability of manganese titanate MnTiO3 at high pressure was investigated by X-ray diffraction and Raman spectroscopy with diamond anvil cells. Ilmenite-type MnTiO3 is stable at least to 26.6 GPa, and lithium niobate type MnTiO3 reversibly transforms at room temperature to perovskite at 2.0 GPa. Bulk moduli （K300） of ilmenite, lithium niobate and perovskite are 174（4） GPa, 179 （8） GPa, and 208（5） GPa, respectively （at fixed first pressure derivative K＇ = 4）. The Griineisen parameter T has been estimated to be 1.28 for ilmenite and 1.75 for perovskite. In ilmenite phase, TiO6 octahedra become more regular with increasing pressure. In perovskite phase structural distortion increases with pressure increase.
文摘Properties of solid C<sub>60</sub> at atmospheric pressure have been widely studied since solid C<sub>60</sub> wasdiscovered. In recent years, the crystal structure, electrical and optical properties of solidC<sub>60</sub> at high pressure have been studied, and some new interesting phenomena observed. Thehigh-pressure X-ray diffracion and electrical resistance measurements showed that solid C<sub>60</sub> hasa phase transition at about 15-22GPa. Recent studies still indicated that solid C<sub>60</sub> has
文摘Ⅰ. INTRODUCTIONAlH<sub>3</sub> is a hydride with higher hydrogen content. Thus, many scientists are very interested in it. In recent years, properties of AlH<sub>3</sub> have been much studied under the atmospheric pressure, but less under high pressure. Our purposes in studying the properties of hydrides under high pressure are as follows:
基金supported by the National Natural Science Foundation of China(Grant No.NSAF.U1330115)the National Major Scientific Instrument and Equipment Development Project of China(Grant No.2012YQ130234)
文摘This study presents high pressure phase transitions and equation of states of cerium under pressures up to 51 GPa at room temperature. The angle-dispersive x-ray diffraction experiments are carried out using a high energy synchrotron x-ray source. The bulk moduli of high pressure phases of cerium are calculated using the Birch-Mumaghan equation. We discuss and correct several previous controversial conclusions, which are caused by the measurement accuracy or personal explanation. The c/a axial ratio of e-Ce has a maximum value at about 29 GPa, i.e., c/a ≈ 1.690.
文摘The deconfinement phase transition from ha-dronic matter to quark matter in the interior of compact stars is investigated. The hadronic phase is described in the framework of relativistic mean-field (RMF) theory, when also the scalar-isovector δ-meson effective field is taken into account. The MIT bag model for describing a quark phase is used. The changes of the pa-rameters of phase transition caused by the pre- sence of δ-meson field are investigated. Finally, alterations in the integral and structure para-meters of hybrid stars due to deconfinement phase transitions are discussed.
基金Supported by the MoST of China 973-Project(2015CB856901)NSFC(11575069,11221504)supported by the Grants-in-Aid for Scientific Research from JSPS(15K05079,15K05098)
文摘We perform a systematic study of elliptic flow（v2） in Au＋Au collisions at √^SNN = 5 GeV by using a microscopic transport model, JAM. The centrality, pseudorapidity, transverse momentum and beam energy dependence of v2 for charged as well as identified hadrons are studied. We investigate the effects of both the hadronic mean-field and the softening of equation of state（EoS） on elliptic flow. The softening of the EoS is realized by imposing attractive orbits in two body scattering, which can reduce the pressure of the system. We found that the softening of the EoS leads to the enhancement of v2, while the hadronic mean-field suppresses v2 relative to the cascade mode. It indicates that elliptic flow at high baryon density regions is highly sensitive to the EoS and the enhancement of v2 may probe the signature of a first-order phase transition in heavy-ion collisions at beam energies of a strong baryon stopping region.
文摘Hydride has a very wide field. Properties of hydrides have been much studied at atmospheric pressure, and hydrides have been extensively applied in research and production. However, their properties at high pressure have been less studied. In recent years, there has been considerable interest in studying properties and metallic transitions of hydrides at high pressure. Straaten et al.have studied the properties of HI at high pressure and discovered an insulator-to-metal transition in HI at pressures of 42.
文摘根据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200GPa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260GPa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200-260GPa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200GPa处出现的微小偏折是由固一液相变引起的，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。
