liquid-crystal transitions

Also contains definitions of: cholesteric phase, nematic phase
https://doi.org/10.1351/goldbook.L03579
A @LT06856@ is a molecular crystal with properties that are both solid- and liquid-like. Liquid crystals are composed predominantly of rod-like or disc-like molecules, that can exhibit one or more different, ordered fluid phases as well as the @I03353@ fluid; the translational order is wholly or partially destroyed but a considerable degree of orientational order is retained on passing from the crystalline to the liquid phase in a @M03847@.
  1. Transition to a nematic phase.
    A @M03847@ that occurs when a molecular crystal is heated to form a nematic phase in which the mean direction of the molecules is parallel or antiparallel to an axis known as the director.
  2. Transition to a cholesteric phase.
    A @M03847@ that occurs when a molecular crystal is heated to form a cholesteric phase in which there is simply a spiralling of the local orientational order perpendicular to the long axes of the molecules.
  3. Transition to a @S05714@.
    A @M03847@ that occurs when a molecular crystal is heated to yield a @S05714@ in which there is a one-dimensional density wave which produces very soft/disordered layers.
Source:
PAC, 1994, 66, 577. (Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)) on page 584 [Terms] [Paper]