Chemistry, Materials Science - Phase Transition

Phase: A state where a substance is uniform and distinctly separated. Physically, we mainly divide them into three phases (solid, liquid, gas), but in materials science, we even distinguish crystal structures. 1. Solid: Hard and resistant to deformation by external forces. 2. Liquid: A state with fluidity; its volume does not decrease when compressed. 3. Gas: A state that expands freely without a fixed volume. 4. Plasma: A phase where electrons and atomic nuclei are separated due to high energy. Phase Transition: The phenomenon where one phase changes into another. In materials science, solid crystal structures are classified into over 15 crystal phases depending on temperature and pressure conditions (diagram on the right). * Unusual Phase Transition Phenomena - Glass Transition Point: The temperature at which a hard solid, like glass, becomes soft like rubber upon heating, but without fluidity (plastic). - Liquid Crystal: Possesses the fluidity of a liquid but the crystallinity of a solid (only in specific substances). However, unlike solids with regular alignment in all three axes, alignment occurs in only one or two directions.