This MedLibrary.org supplementary page on Tricritical point is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
A tricritical point is a point in the phase diagram of a system at which three-phase coexistence terminates1. This definition is clearly parallel to the definition of an ordinary critical point as the point at which two-phase coexistence terminates.
A line of three-phase coexistence is termed a triple point for a one-component system, since, from Gibbs' phase rule, this condition is only achieved for a single point in the phase diagram (F=2-3+1=0). For tricritical points to be observed, one need a mixture with more components. It can be shown2 that three is the minimum number of components for which these points can appear. In this case, one may have a two-dimensional region of three-phase coexistence (F=2-3+3=2) (thus, each point in this region corresponds to a triple point). This region will terminate in two critical lines of phase coexistence; these two critical lines may then terminate at a single tricritical point. This point is therefore "twice critical", since it belong to two critical branches. Indeed, its critical behavior is different from critical points: the critical dimension is lowered so the classical exponents turn out to apply for real systems.
It seems more convenient experimentally to consider mixtures with four components for which one thermodynamic variable (usually the pressure or the volume) is kept fixed. The situation then reduces to the one described for mixtures of three components.
References
Wikipedia content modification information:
- This page was last modified on 9 June 2008, at 07:53.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Tricritical point".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.