Dissertation > Excellent graduate degree dissertation topics show

Phase transition of liquid crystal molecules biaxial elastic rectangular plate bond connected nematic phase

Author: LiZuo
Tutor: LiuHong
School: Nanjing Normal University
Course: Condensed Matter Physics
Keywords: biaxial nematic liquid crystal phase transition tetrapodes
CLC: O753.2
Type: Master's thesis
Year: 2012
Downloads: 3
Quote: 0
Read: Download Dissertation

Abstract


The phase transitions of molecular system consisted by rectangular plates connected by flexible chain are studied in this paper. We consider two kinds of molecular model.(1) A molecular system consisted by double rectangular plates is considered. Based on a simple interaction energy between molecules and the approximation of mean-field theory, as the interaction strength of flexible chain increases, four kinds of phase diagrams in the plane of molecular structure and temperature are obtained.In the first kind (where the interaction strength is the smallest) there is only one Landau point that allows system directly transit from isotropic phase to biaxial phase.In the second kind Landau point spreads to a Landau curve. The region of positive uniaxial phase increases and that of negative uniaxial phase decreases.In the phase diagram, a first order transition from uniaxial phase to biaxial phase appears. In the third kind Landau point also spreads to a Landau curve, but the region of negative uniaxial phase disappears.In the fourth kind (the interaction strength of flexible chain is the largest), the range of Landau curve becomes narrower. The above phase diagrams show that the phase transition types, appearance and the range of Laudau curve depend on the size of the flexible chain.(2) The second model is a molecular system consisted by a rectangular plate and a stick. Based on a simple interaction energy between molecules and the approximation of mean-field theory, four kinds of phase diagrams in the plane of temperature and molecular structure are obtained. In the first kind (where the interaction strength is to make two sticks parallel) there is only one Landau point that allows system directly transit from isotropic phase to biaxial phase.In the second kind Landau point moves to the right, and the region of positive uniaxial phase increases and that of negative uniaxial phase disappears.In the third kind (where the interaction strength is to make two sticks vertical), Landau point spreads to a Landau curve. The system can enter to the biaxial phase at high temperature easily. In the fourth kind (where the interaction strength is to make three sticks vertical), Landau curve becomes Landau point. The above phase diagrams show that the phase transition type, appearance and the range of Laudau curve depend on the molecular structure and the flexible chain.

Related Dissertations

  1. The Topological Phase Transition of Asymmetric Two-component Fermi Gas in Two Dimensions,O469
  2. Preparation of Chiral Silica Nanofibers Using Achiral Cationic Surfactant as Templates,TB383.1
  3. Preparation and Rheological Properties of Nanogel Aqueous Dispersions/supramolecular Composite Hydrogel,O648.17
  4. Reseach of Temperature Sensitive Nanogels with Tuned Temperature Sensitivity,TB383.1
  5. Ising Universality Quantum Spin Chains Based on the Finite Matrix Product State Representations,O413
  6. Study on Matrix Product States and Quantum Discord in One-dimensional Systems,O469
  7. Multi-layer multi sublattice study the physical properties of thin film materials,TB383.2
  8. Study on Preparation, Structure and Electric Properties of NBT-based Lead-free Piezoelectric Ceramics,TM282
  9. The Spin-wave Excitations of the Collinear Antiferromagnetic Phase in Iron Pnictides,O469
  10. Thermoelectric properties of nano - PbTe under high pressure,O469
  11. The Numerical Simulation Study on Effect of Phase Transition in Hypervelocity Impacting,O35
  12. Synthesis of CdSe Nanocrystals by Organic Solvent and Modified with Surfactant,TB383.1
  13. Monte Carlo Simulation on the Magnetic Properties of a Honeycomb Monolayer Film,O482.5
  14. Analytically Study of Kinetic Ising Model within an Effective-field Theory with Correlations,O313
  15. Study of Infrared Optical Properties in Perovskite Manganese Oxide La1-xCaxMnO3,P575
  16. Noise-Induced Phase Transition: Zero-Dimensiona Brownian Particles Subjected to a Time Derivative Noise,O552.1
  17. First-Principles Investigations of the Pressure-Induced Structrual Transitions in Ternary Alkali Metal Hydrides,O521.23
  18. Non axisymmetric LCD system by the isotropic phase to the biaxial nematic phase transition,O753.2
  19. Phase Transition and Rectification in Two Dimensional Frenkel-Kontorova Model,O469
  20. Study on Radial Heat Pipe Media Shutdown,TE832
  21. Effect of Doping on Electroinc Structure and Magnetic Properties of Half-Heusleralloys,TG139.6

CLC: > Mathematical sciences and chemical > Crystallography > Amorphous and class crystalline > Class crystalline > Liquid crystal
© 2012 www.DissertationTopic.Net  Mobile