Difference between revisions of "Phase transition"
From Online Dictionary of Crystallography
(Created page with "<font color="blue">Transition de phase</font> (''Fr''); <font color="red">Phasenübergang</font> (''Ge''); <font color="green">Cambio de estado</font> ( ''Sp''); <font color="bla...") |
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| − | <font color="blue">Transition de phase</font> (''Fr''); <font color="red">Phasenübergang</font> (''Ge''); <font color="green">Cambio de estado</font> ( ''Sp''); <font color="black">Transizione di fase</font> (''It''); <font color="brown">Фазовый переход</font> (''Ru'');<font color="purple">相転移</font> ( ''Ja''). | + | <font color="blue">Transition de phase</font> (''Fr''); <font color="red">Phasenübergang</font> (''Ge''); <font color="green">Cambio de estado</font> ( ''Sp''); <font color="black">Transizione di fase</font> (''It''); <font color="brown">Фазовый переход</font> (''Ru'');<font color="purple">相転移</font> (''Ja''). |
A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another one by heat transfer. The term is most commonly used to describe transitions between solid, liquid and gaseous states of matter, and, in rare cases, plasma. | A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another one by heat transfer. The term is most commonly used to describe transitions between solid, liquid and gaseous states of matter, and, in rare cases, plasma. | ||
| − | Phase transitions | + | Phase transitions of crystallographic interest are those involving solid phases: with the change of the external conditions (temperature, pressure, applied field) the crystal structure undergoes a change that, when it is not accompanied by a change in the chemistry, relates [[polymorphism|polymorphs]]. |
Phase transitions are classified on the basis of different criteria. | Phase transitions are classified on the basis of different criteria. | ||
Revision as of 09:05, 14 April 2017
Transition de phase (Fr); Phasenübergang (Ge); Cambio de estado ( Sp); Transizione di fase (It); Фазовый переход (Ru);相転移 (Ja).
A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another one by heat transfer. The term is most commonly used to describe transitions between solid, liquid and gaseous states of matter, and, in rare cases, plasma.
Phase transitions of crystallographic interest are those involving solid phases: with the change of the external conditions (temperature, pressure, applied field) the crystal structure undergoes a change that, when it is not accompanied by a change in the chemistry, relates polymorphs.
Phase transitions are classified on the basis of different criteria.
- Mechanistic classification (Buerger): reconstructive (with changes in the pattern of chemical bonds), displacive (characterised by only small atomic shifts), order-disorder (of the atomic distribution on given Wyckoff positions).
- Thermodynamic classification (Ehrenfest; Tisza): first-order (exhibit a discontinuity in the first derivative of the free energy with respect to some thermodynamic variable), second-order (continuous in the first derivative but exhibit discontinuity in a second derivative of the free energy), lambda (the heat capacity shows a kink at the transition temperature)
While reconstructive phase transitions are always first order, displacive phase transitions can be both first and second order.