Phase (matter)
From Wikipedia, the free encyclopedia
Not to be confused with State of matter.
In the physical sciences, a phase is a region of space (a thermodynamic system), throughout which all physical properties of a
material are essentially uniform. Examples of physical properties include density, index of refraction, magnetization and
chemical composition. A simple description is that a phase is a region of material that is chemically uniform, physically
distinct, and (often) mechanically separable. In a system consisting of ice and water in a glass jar, the ice cubes are one phase,
the water is a second phase, and the humid air is a third phase over the ice and water. The glass of the jar is another separate
phase.
Q: Everybody understands things like solid, liquid or gaseous state of substance. We call them solid, liquid or gaseous phases,
respectively. This is intuitive but hardly rigorous. Chemists, I'm told, consider a cup of sweetened tea to be a single phase,
even when the concentration of sugar at the bottom is maximal and nearly zero at the free surface (no mixing was applied to
dissolve the sugar). Is this indeed correct?
A: A phase, or state of matter, is a domain within a many-body system within which relevant physical properties are uniform.
Relevant properties may include chemical composition, stoichiometry, and density, which do not reflect how the components
are arranged in space. Different domains with the same physical properties are said to be in the same phase even if they
differ in such thermodynamically irrelevant parameters as orientation. Thus ice cubes in a glass of water are all in the
crystalline phase. So also with magnetic domains in a ferromagnet.
For systems out of equilibrium, the definition of phases and phase transitions is far more varied and complicated.
Binární isomorfní fázový diagram
https://www.youtube.com/watch?v=dAKt_3GQfNs
Eutektický fázový diagram
https://www.youtube.com/watch?v=1Z17yIm9dMI
Eutektická struktura
https://www.youtube.com/watch?v=MuFPJhiQKC8
Video eutekticka struktura
Příklady složitých diagramů
https://www.youtube.com/watch?v=JLzJrguM_gI