期刊文献+
共找到431篇文章
< 1 2 22 >
每页显示 20 50 100
Dielectric anisotropy in liquid crystal mixtures with nematic and smectic phases
1
作者 汤星舟 叶家耀 +4 位作者 王子烨 姜皓译 尚小虎 杨朝雁 李炳祥 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期519-524,共6页
The modulation of dielectric anisotropy(△ε)is pivotal for elucidating molecular interactions and directing the alignment of liquid crystals.In this study,we combine liquid crystals with opposing dielectric anisotrop... The modulation of dielectric anisotropy(△ε)is pivotal for elucidating molecular interactions and directing the alignment of liquid crystals.In this study,we combine liquid crystals with opposing dielectric anisotropies to explore the impact of varying concentrations on their properties.We report the sign-reversal of△εin both the nematic and smectic A phases of these mixed liquid crystals,alongside a dual-frequency behaviour across a broad temperature spectrum.Our research further quantifies the influence of mixture ratios under various temperatures and electric field frequencies.This exploration may pave the way for the discovery of new physical phenomena. 展开更多
关键词 mixed liquid crystal dielectric anisotropy TUNABLE nematic SMECTIC
下载PDF
THE EXISTENCE AND UNIQUENESS OF TIME-PERIODIC SOLUTIONS TO THE NON-ISOTHERMAL MODEL FOR COMPRESSIBLE NEMATIC LIQUID CRYSTALS IN A PERIODIC DOMAIN
2
作者 陈爽 郭闪闪 许秋菊 《Acta Mathematica Scientia》 SCIE CSCD 2024年第3期947-972,共26页
In this paper,we are concerned with a three-dimensional non-isothermal model for the compressible nematic liquid crystal flows in a periodic domain.Under some smallness and structural assumptions imposed on the time-p... In this paper,we are concerned with a three-dimensional non-isothermal model for the compressible nematic liquid crystal flows in a periodic domain.Under some smallness and structural assumptions imposed on the time-periodic force,we establish the existence of the time-periodic solutions to the system by using a regularized approximation scheme and the topological degree theory.We also prove a uniqueness result via energy estimates. 展开更多
关键词 compressible nematic liquid crystals time-periodic solution topological degree theory energy estimates
下载PDF
ENERGY CONSERVATION FOR THE WEAK SOLUTIONS TO THE 3D COMPRESSIBLE NEMATIC LIQUID CRYSTAL FLOW
3
作者 谭忠 李心亮 杨惠 《Acta Mathematica Scientia》 SCIE CSCD 2024年第3期851-864,共14页
In this paper,we establish some regularity conditions on the density and velocity fields to guarantee the energy conservation of the weak solutions for the three-dimensional compressible nematic liquid crystal flow in... In this paper,we establish some regularity conditions on the density and velocity fields to guarantee the energy conservation of the weak solutions for the three-dimensional compressible nematic liquid crystal flow in the periodic domain. 展开更多
关键词 compressible nematic liquid crystal flow weak solutions energy conservation
下载PDF
GLOBAL EXISTENCE OF WEAK SOLUTIONS TO THE NON-ISOTHERMAL NEMATIC LIQUID CRYSTALS IN 2D 被引量:4
4
作者 李进开 辛周平 《Acta Mathematica Scientia》 SCIE CSCD 2016年第4期973-1014,共42页
In this article, we prove the global existence of weak solutions to the non- isothermal nematic liquid crystal system on T2, on the basis of a new approximate system which is different from the classical Ginzburg-Land... In this article, we prove the global existence of weak solutions to the non- isothermal nematic liquid crystal system on T2, on the basis of a new approximate system which is different from the classical Ginzburg-Landau approximation. Local in space energy inequalities are employed to recover the estimates on the second order spatial derivatives of the director fields locally in time, which cannot be derived from the basic energy balance. It is shown that these weak solutions satisfy the temperature equation, and also the total energy equation but away from at most finite many "singular" times, at which the energy concentration occurs and the director field losses its second order derivatives. 展开更多
关键词 Global weak solutions NON-ISOTHERMAL nematic liquid crystals
下载PDF
Determining the sum of flexoelectric coefficients in nematic liquid crystals by the capacitance method 被引量:3
5
作者 叶文江 邢红玉 +3 位作者 崔文静 周璇 孙玉宝 张志东 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第11期414-421,共8页
A detailed theoretical analysis of determining the sum of flexoelectric coefficients in nematic liquid crystals using the capacitance method is given. In the strong anchoring parallel aligned nematic (PAN) and hybri... A detailed theoretical analysis of determining the sum of flexoelectric coefficients in nematic liquid crystals using the capacitance method is given. In the strong anchoring parallel aligned nematic (PAN) and hybrid aligned nematic (HAN) cells, the dependences of the capacitance on the sum of flexoelectric coefficients and the applied voltage are obtained by numerical simulations, and the distributions of the director and the electric potential for different applied voltages and flexoelectric coefficients are also given. Based on this theoretical analysis, we propose an experimental design for measuring the capacitance of a liquid crystal cell using the improved precision LCR meter E4980A (Agilent). Through comparing the experimental data with the simulated results, the sum of flexoeletric coefficients can be determined. 展开更多
关键词 FLEXOELECTRICITY CAPACITANCE parallel aligned nematic and hybrid aligned nematic liquid crystals
下载PDF
ASYMPTOTIC BEHAVIOR OF SOLUTIONS TO THE COMPRESSIBLE NEMATIC LIQUID CRYSTAL SYSTEM IN R3 被引量:2
6
作者 李银 位瑞英 姚正安 《Acta Mathematica Scientia》 SCIE CSCD 2017年第1期174-186,共13页
In this paper,we study a nematic liquid crystals system in three-dimensional whole space R3 and obtain the time decay rates of the higher-order spatial derivatives of the solution by the method of spectral analysis an... In this paper,we study a nematic liquid crystals system in three-dimensional whole space R3 and obtain the time decay rates of the higher-order spatial derivatives of the solution by the method of spectral analysis and energy estimates if the initial data belongs to L1(R3) additionally. 展开更多
关键词 nematic liquid crystals decay rates spectral analysis
下载PDF
LPS'S CRITERION FOR INCOMPRESSIBLE NEMATIC LIQUID CRYSTAL FLOWS 被引量:3
7
作者 陈卿 谭忠 吴国春 《Acta Mathematica Scientia》 SCIE CSCD 2014年第4期1072-1080,共9页
In this paper we derive LPS's criterion for the breakdown of classical solutions to the incompressible nematic liquid crystal flow, a simplified version of Ericksen-Leslie system modeling the hydrodynamic evolution o... In this paper we derive LPS's criterion for the breakdown of classical solutions to the incompressible nematic liquid crystal flow, a simplified version of Ericksen-Leslie system modeling the hydrodynamic evolution of nematic liquid crystals in R^3. We show that if 0 〈 T 〈 +∞ is the maximal time interval for the unique smooth solution u ∈ C^∞([0, T),R^3),then |u|+|△d|∈L^q([0,T],L^p(R^3)),where p and q satisfy the Ladyzhenskaya-Prodi-Serrin's condition:3/p+2/q=1 and p∈(3,+∞]. 展开更多
关键词 incompressible nematic liquid crystal flow Ladyzhenskaya-Prodi-Serrin's criterion
下载PDF
BLOW-UP CRITERION OF CLASSICAL SOLUTIONS FOR THE INCOMPRESSIBLE NEMATIC LIQUID CRYSTAL FLOWS 被引量:1
8
作者 高真圣 谭忠 《Acta Mathematica Scientia》 SCIE CSCD 2017年第6期1632-1638,共7页
In this paper, we consider the short time classical solution to a simplified hydro-dynamic flow modeling incompressible, nematic liquid crystal materials in R3. We establisha criterion for possible breakdown of such s... In this paper, we consider the short time classical solution to a simplified hydro-dynamic flow modeling incompressible, nematic liquid crystal materials in R3. We establisha criterion for possible breakdown of such solutions at a finite time. More precisely, if (u, d)is smooth up to time T provided that ∫T 0‖△×u(t, ·)‖BMO(R3) +‖△d(t, ·)‖8L4(R3)dt 〈∞. 展开更多
关键词 INCOMPRESSIBLE nematic liquid crystal blow up criterion
下载PDF
Temperature dependence of ratio between dielectric anisotropy and order parameter in fluorinated nematic liquid crystals
9
作者 马恒 孙瑞芝 +1 位作者 李振新 刘玉芳 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第1期255-258,共4页
Temperature dependence of ratio between dielectric anisotropy and order parameter of fluorinated nematic liquid crystal is investigated by using a semi-empirical molecular orbital package that can accurately calculate... Temperature dependence of ratio between dielectric anisotropy and order parameter of fluorinated nematic liquid crystal is investigated by using a semi-empirical molecular orbital package that can accurately calculate an angle between molecular dipole moment and long axis. We optimize the molecular conformations with three semi-empirical Hamiltonians AM1, PM3 and PM5, and then make a comparison between computational results and experimental measurements. It is shown that the results obtained from AM1 method are in good agreement with the measurements. The present study offers an applicable method to predict the dielectric properties of liquid crystal material. 展开更多
关键词 dielectric anisotropy order parameter FLUORINE nematic liquid crystal
下载PDF
COMPENSATION EFFECT OF POLYIMIDE THIN FILMS ON NORMALLY WHITE TWISTED NEMATIC LIQUID CRYSTAL DISPLAYS
10
作者 李宝忠 何天白 丁孟贤 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 1997年第2期139-145,共7页
The disadvantages of Normally White Twisted Nematic Liquid Crystal Display (NW-TN-LCD) were discussed. The reason that the negative birefringent polyimide thin films were used to compensate NW-TN-LCD to decrease off-a... The disadvantages of Normally White Twisted Nematic Liquid Crystal Display (NW-TN-LCD) were discussed. The reason that the negative birefringent polyimide thin films were used to compensate NW-TN-LCD to decrease off-axis leakage, improve contrast ratios and enlarge viewing angles was explained in this paper. A certain polyimide thin film was taken as an example to show compensation effect on NW-TN-LCD. 展开更多
关键词 polyimide thin films RETARDATION compensation negative birefringence normally white twisted nematic liquid crystal display
下载PDF
Calculating the dielectric anisotropy of nematic liquid crystals:a reinvestigation of the Maier-Meier theory
11
作者 张然 何军 +1 位作者 彭增辉 宣丽 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第7期2885-2892,共8页
This paper investigates the average dielectric permittivity (^-ε) in the Maier-Meier theory for calculating the dielectric anisotropy (△ε) of nematic liquid crystals.For the reason that ^-ε of nematics has the... This paper investigates the average dielectric permittivity (^-ε) in the Maier-Meier theory for calculating the dielectric anisotropy (△ε) of nematic liquid crystals.For the reason that ^-ε of nematics has the same expression as the dielectric permittivity of the isotropic state,the Onsager equation for isotropic dielectric was used to calculate it.The computed ^-ε shows reasonable agreement with the results of the numerical methods used in the literature.Molecular parameters,such as the polarizability and its anisotropy,the dipole moment and its angle with the molecular long axis,were taken from semi-empirical quantum chemistry (MOCPAC/AM1) modeling.The calculated values of △ε according to the Maier-Meier equation are in good agreement with the experimental results for the investigated compounds having different core structures and polar substituents. 展开更多
关键词 dielectric anisotropy molecule modeling semi-empirical quantum chemistry nematic liquid crystals
下载PDF
Molecular theory of nematic liquid crystals viewed as effect of collective excitation in ferromagnetic systems
12
作者 刘建军 沈曼 +1 位作者 刘晓静 杨国琛 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第1期163-171,共9页
We develop a microscopic theory of the nematic phase with consideration of the effect of the collective excitation on properties of nematic liquid crystals. The model is based on the Heisenberg's exchange model of th... We develop a microscopic theory of the nematic phase with consideration of the effect of the collective excitation on properties of nematic liquid crystals. The model is based on the Heisenberg's exchange model of the ferromagnetic materials. Since the orientation of the molecular long axis and the angular momentum of the molecule rotating around its long axis have the same direction, operators can be introduced to research the nematic liquid crystals. Using the lattice model and the Holstein-Primakoff transformation, the Hamiltonian of the system can be obtained, which has the same form as that of the ferromagnetic substance. The relation between the order parameter and reduced temperature can be gotten. It is in good agreement with the experimental results in the low temperature region, the accordance is better than that of the molecular field theory and the computer simulation. In high temperature region close to the transition point, by considering the effect of the higher-order terms in the Hamiltonian, theoretical prediction is in better agreement with the experiment. That indicates the many-body effect is important to nematic liquid crystals. 展开更多
关键词 nematic liquid crystals collective excitation order parameters
下载PDF
Two-Dimensional Spatial Solitons in Nematic Liquid Crystals
13
作者 ZHONG Wei-Ping YANG Zheng-Ping +2 位作者 XIE Rui-Hua Milivoj Beliè Goong Chen 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第2期324-330,共7页
We study the propagation of spatial solitons in nematic liquid crystals, using the self-similar method. Analytical solutions in the form of self-similar solitons are obtained exactly. We confirm the stability of these... We study the propagation of spatial solitons in nematic liquid crystals, using the self-similar method. Analytical solutions in the form of self-similar solitons are obtained exactly. We confirm the stability of these solutions by direct numerical simulation, and find that the stable spatial solitons can exist in various forms, such as Oaussian solitons, radially symmetric solitons, multipole solitons, and soliton vortices. 展开更多
关键词 nonlinear optics spatial solitons self-similar method nematic liquid crystals
下载PDF
Lattice Boltzmann Simulation of 3D Nematic Liquid Crystal near Phase Transition
14
作者 ZHANGJun TAORui-Bao 《Communications in Theoretical Physics》 SCIE CAS CSCD 2002年第2期253-256,共4页
Phase transition between nematic and isotropic liquid crystal is a very weak first order phase transition.We avoid to use the normal Landau-de Gennes's free energy that reduces a strong first order transition, and... Phase transition between nematic and isotropic liquid crystal is a very weak first order phase transition.We avoid to use the normal Landau-de Gennes's free energy that reduces a strong first order transition, and set up adata base of free energy calculated by means of Tao-Sheng Lin's extended molecular field theory that can explain theexperiments of the equilibrium properties of nematic liquid crystal very well. Then we use the free energy method oflattice Boltzmann developed by Oxford group to study the phase decomposition, pattern formation in the flow of theliquid crystal near transition temperature. 展开更多
关键词 nematic liquid crystal lattice Boltzmann spinodal decomposition
下载PDF
Asymmetric dynamic phase holographic grating in nematic liquid crystal
15
作者 任常愚 石宏新 +3 位作者 艾延宝 尹向宝 王丰 丁红伟 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第9期105-109,共5页
A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal(NLC) was presented.An oblique incidence beam was used to record the thin asym... A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal(NLC) was presented.An oblique incidence beam was used to record the thin asymmetric dynamic phase holographic grating.The diffraction efficiency we achieved is more than 40%,exceeding the theoretical limit for symmetric profile gratings.Both facts can be explained by assuming that a grating with an asymmetric saw-tooth profile is formed in the NLC.Finally,physical mechanism and mathematical model for characterizing the asymmetric phase holographic grating were presented,based on the photo-refractive-like(PR-like) effect. 展开更多
关键词 nematic liquid crystal asymmetric phase grating diffraction efficiency photorefractive effect
下载PDF
Theory of nine elastic constants of biaxial nematics 被引量:2
16
作者 刘红 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第3期1060-1069,共10页
In this paper, a rotational invariant of interaction energy between two biaxial-shaped molecules is assumed and in the mean field approximation, nine elastic constants for simple distortion patterns in biaxial nematic... In this paper, a rotational invariant of interaction energy between two biaxial-shaped molecules is assumed and in the mean field approximation, nine elastic constants for simple distortion patterns in biaxial nematics are derived in terms of the thermal average (Dmn^(l)) (Dm'n'^(l')), where Dmn^(l) is the Wigner rotation matrix. In the lowest order terms, the elastic constants depend on coefficients Γ,Γ', λ, order parameters Q0 = Q0(D00^(2)) +Q2(D02^(2)+D0-2^(2)) and Q2 = Q0(D20^(2)) + Q2(D22^(2)+D2-2^(2)). Here Γ and Γ' depend on the function form of molecular interaction energy vj′j″j (τ12) and probability function fk′k″k (τ12), where r12 is the distance between two molecules, and λ is proportional to temperature. Q0 and Q2 are parameters related to multiple moments of molecules. Comparing these results with those obtained from Landau-de Gennes theory, we have obtained relationships between coefficients, order parameters used in both theories. In the special case of uniaxial nematics, both results are reduced to a degenerate case where K11=K33. 展开更多
关键词 biaxial nematic liquid crystal elastic theory
下载PDF
Synthesis and mesomorphic behavior of benzothiazole-based liquid crystals having terminal methoxyl group 被引量:1
17
作者 Sie Tiong Ha Teck Ming Koh +1 位作者 Siew Teng Ong Yasodha Sivasothy 《Chinese Chemical Letters》 SCIE CAS CSCD 2009年第12期1449-1452,共4页
A homologous series of benzothiazole derivatives, 6-methoxy-2-(4-alkanoyloxybenzylidenamino)benzothiazoles, were synthesized and characterized using FT-IR, ^1H and ^13C NMR, mass spectrometry and elemental analysis.... A homologous series of benzothiazole derivatives, 6-methoxy-2-(4-alkanoyloxybenzylidenamino)benzothiazoles, were synthesized and characterized using FT-IR, ^1H and ^13C NMR, mass spectrometry and elemental analysis. Enantiotropic nematic phase was observed throughout the entire series. Smectic C phase only emerged from the decanoyloxy derivative onwards. The terminal methoxyl group and the ester linkage influenced the mesomorphic behavior of the present series. 展开更多
关键词 BENZOTHIAZOLE Schiff bases nematic Smectic C liquid crystal
下载PDF
STUDY ON LIQUID CRYSTAL POLYMERS WITH TWO-DIMENSIONAL MESOGENIC UNITS 被引量:1
18
作者 张春晓 李自法 +1 位作者 周其凤 周洪兵 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 1993年第4期58-63,共6页
A series of liquid crystalline polymers with two-dimensional mesogenic units were synthesized by solution polycondensation at low temperature. All the polymers were liquid crystalline. The melting temperature T;(exce... A series of liquid crystalline polymers with two-dimensional mesogenic units were synthesized by solution polycondensation at low temperature. All the polymers were liquid crystalline. The melting temperature T;(except that with substituent of methoxy) and the clearing temperature T;of the polymers change regularly with varying of the length of the alkyl substituent groups. 展开更多
关键词 liquid crystal polymer Two-dimensional mesogenic unit N-2 ' 5 '-dihydroxy benzylidene-4-alkoxyaniline Monotropic nematics
下载PDF
Dynamic Rheological Characterization of A Thermotropic Liquid Crystalline Poly (aryl ether ketone)
19
作者 Hui SUN Wan Jin ZHANG +3 位作者 Zhong Wen WU Li Wei LI Bi Bo YANG Qiang ZHENG 《Chinese Chemical Letters》 SCIE CAS CSCD 2001年第3期273-274,共2页
The rheometries ARES rheometer was applied to determining the rheological behavior of a thermotropic liquid crystalline poly (aryl ether ketone). The viscosity of the material decreases with increasing temperature. re... The rheometries ARES rheometer was applied to determining the rheological behavior of a thermotropic liquid crystalline poly (aryl ether ketone). The viscosity of the material decreases with increasing temperature. reaching a minimum in the nematic state, then slightly increases with further raising the temperature in the biphase. 展开更多
关键词 Poly (aryl ether ketone) liquid crystal nematic VISCOSITY RHEOLOGY
下载PDF
Rotational viscosity of a liquid crystal mixture: a fully atomistic molecular dynamics study
20
作者 张然 彭增辉 +2 位作者 刘永刚 郑致刚 宣丽 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第10期4380-4385,共6页
Fully atomistic molecular dynamics (MD) simulations at 293, 303 and 313 K have been performed for the four- component liquid crystal mixture, E7, using the software package Material Studio. Order parameters and orie... Fully atomistic molecular dynamics (MD) simulations at 293, 303 and 313 K have been performed for the four- component liquid crystal mixture, E7, using the software package Material Studio. Order parameters and orientational time correlation functions (TCFs) were calculated from MD trajectories. The rotational viscosity coefficients (RVCs) of the mixture were calculated using the Nemtsov-Zakharov and Fialkowski methods based on statistical-mechanical approaches. Temperature dependences of RVC and density were discussed in detail. Reasonable agreement between the simulated and experimental values was found. 展开更多
关键词 rotational viscosity molecular dynamic simulation nematic liquid crystal MIXTURE
下载PDF
上一页 1 2 22 下一页 到第
使用帮助 返回顶部