Ever wondered what "liquid crystal" is? Here’s an intro

1
Ever wondered what "liquid crystal" is?
Heres an intro
2
Introduction
Liquid crystal is a state of matter like
liquid, solid, and gas. The term liquid crystal
is used to denote a material that exhibits a
liquid phase under certain conditions. In order
to understand what differentiates a liquid
crystal phase from a liquid or solid phase, it is
necessary to understand what defines these
phases.
3

• The difference lies in the order of matter on a
  molecular, atomic or subatomic level. Order is a
  function of the energy stored within matter, and
  hence a function of the temperature of matter. 
• Thus, one could say that temperature equals
  motion. There is no motion at absolute zero
  temperature (0 Kelvin).
• Very close to absolute zero, a state of matter
  called the Bose-Einstein condensate can exist.
• A little further away from absolute zero we have
  solids, which are characterized by limited motion
  of the molecules, atoms and ions that make up the
  material. 
• This limited motion is a vibration within the
  molecule, and an oscillation around a fixed
  position. In a crystal for example, the centers
  of gravity within the molecules vibrate around
  fixed positions on a crystal lattice, while the
  general orientation of non-spherical molecules
  vibrates around a preferred orientation.

4

• When a solid melts, this long range order (fixed
  average position, fixed average orientation many
  thousands of molecular units across) breaks up. 
• If both long range orders (position and
  orientation) dissipate at the same time as when
  the melting point is reached, a liquid phase is
  formed.
• In a liquid, there still is some level of order,
  but only in a short range (i.e. a few molecules
  across). The hydrogen bonds between water
  molecules are a good example.
• When, with increasing temperature, this short
  range order gets lost and the molecules become
  completely independent in their motion, we speak
  about a gas or vapor.
• Finally, when electrons or other sub-atomic
  particles lose their order with respect to the
  rest of the molecule, we speak about plasma.

5

• Nature does not require that each phase is
  formed Some materials can go from solid to gas
  without a liquid phase. Neither does nature
  require that positional and orientational order
  get lost in one step and at the same temperature.
• Depending on environmental conditions such as
  pressure or solvent concentration in a mixture,
  phases may be skipped or additional phases may
  appear when changing the temperature of a
  material.
• If positional order gets lost at the melting
  point, but orientational long range order is
  maintained up to a higher temperature, a liquid
  crystal phase is formed.
• The temperature at which all orientational long
  range order gets lost is called clearing point,
  as at such temperature a typically milky liquid
  crystal turns into a clear fluid.

6

• Positional long range order can get lost in
  steps while orientational order is maintained. As
  a result there can be many liquid crystal phases
  with different geometry and distinct phase
  transition temperatures between them. In some
  phases the liquid crystal is aligned in layers.
  They are called smectic phases and letters are
  used to differentiate different geometries
  (smectic A, smC, smI). Columnar phases have
  molecules aligned in columns. The liquid crystal
  phase with no long range positional order is
  called a nematic phase and it is most widely used
  in displays.

Liquid crystal phases are useful in displays
because they interact with light and electric
fields like crystals, but they can move (flow)
like liquids, making it possible to use electric
fields to change their effect on light.
7

• A typical temperature range of the liquid crystal
  phase(s) of a single material is only a few
  degrees. For most materials, that range is well
  above room temperature. In order to make liquid
  crystals practical for use in LCD displays, they
  need to be blended. 
• Mixtures of liquid crystal materials can be
  formulated so that their temperature range is
  wide and falls within the operating temperature
  range requirements of modern electronics devices.
• Liquid Crystal Fluid suppliers engage in
  researching new material groups, synthesizing
  materials, and blending mixtures to achieve the
  physical properties defined by display
  manufacturers. Blends contain some 10-25 single
  substances.

8

• A typical calamitic liquid crystal material that
  may be used in such blends is 5OCB

In a volume model it would appear like this
9
Or simplified like a rod or cigar
10
Source

• To read more visit at http//newvisiondisplay.com
  /liquid-crystal/

11
Thank You
A presentation by
To schedule a meeting with our team, please
email us at  sales_at_newvisiondisplay.com