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Multicritical Point
Multicritical points are special points in the parameter space of thermodynamic or other systems with a continuous phase transition. At least two thermodynamic or other parameters must be adjusted to reach a multicritical point. At a multicritical point the system belongs to a universality class different from the "normal" universality class. A more detailed definition requires concepts from the theory of critical phenomena, a branch of physics that reached a very satisfying state in the 1970s. Definition The union of all the points of the parameter space for which the system is critical is called a critical manifold. As an example consider a substance ferromagnetic below a transition temperature T_, and paramagnetic above T_c. The parameter space here is the temperature axis, and the critical manifold consists of the point T_c. Now add hydrostatic pressure P to the parameter space. Under hydrostatic pressure the substance normally still becomes ferromagnetic b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase Transition
In chemistry, thermodynamics, and other related fields, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states of matter: solid, liquid, and gas, and in rare cases, plasma. A phase of a thermodynamic system and the states of matter have uniform physical properties. During a phase transition of a given medium, certain properties of the medium change as a result of the change of external conditions, such as temperature or pressure. This can be a discontinuous change; for example, a liquid may become gas upon heating to its boiling point, resulting in an abrupt change in volume. The identification of the external conditions at which a transformation occurs defines the phase transition point. Types of phase transition At the phase transition point for a substance, for instance the boiling point, the two phases involved - liquid and vapor, have identic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
