Physics:Liquid-liquid critical point
A liquid-liquid critical point (or LLCP) is the endpoint of a liquid-liquid phase transition line (LLPT); it is a critical point where two types of local structures coexist at the exact ratio of unity. This hypothesis was first developed by H. Eugene Stanley[1] to obtain a quantitative understanding of the huge number of anomalies present in water.[2] Near a liquid-liquid critical point, there is always a mixture of two alternative local structures. For instance, in supercooled water, two types of local structures exist, a low-density liquid (LDL) and a high-density liquid (HDL), so above the critical pressure, a higher percentage of HDL exists while below the critical pressure a higher percentage of LDL is present. The ratio r = LDL/(LDL + HDL) of phase amounts [clarification needed] is determined according to the thermodynamic equilibrium of the system, which is often governed by external variables such as pressure and temperature.[3] A discontinuity is present in r when crossing the liquid-liquid phase transition, which separates the LDL-rich phase from the LDL-poor phase. At any point of the liquid-liquid phase transition, including the associated liquid-liquid critical point, the ratio of LDL to HDL is exactly one (r = ½).
The liquid-liquid critical point theory can be applied to all liquids that possess the tetrahedral symmetry. The study of liquid-liquid critical points is an active research area with hundreds of papers having been published, though only a few of these investigations have been experimental[4][5][6][7][8][9] since most modern probing techniques are not fast and/or sensitive enough to study them.
References
- ↑ Poole, P. H.; Sciortino, F.; Essmann, U.; Stanley, H. E. (1992). "Phase Behavior of Metastable Water". Nature 360 (6402): 324–328. doi:10.1038/360324a0. Bibcode: 1992Natur.360..324P.
- ↑ "Anomalous properties of water". http://www1.lsbu.ac.uk/water/water_anomalies.html. Retrieved 30 August 2015.
- ↑ Holten, V.; Palmer, J. C.; Poole, P. H.; Debenedetti, P. G.; Anisimov, M. A. (2014). "Two-state thermodynamics of the ST2 model for supercooled water". J. Chem. Phys. 140 (10): 104502. doi:10.1063/1.4867287. PMID 24628177. Bibcode: 2014JChPh.140b4502M.
- ↑ Mishima, O.; Stanley, H. E. (1998). "Decompression-Induced Melting of Ice IV and the Liquid-Liquid Transition in Water.". Nature 392 (6672): 164–168. doi:10.1038/32386. Bibcode: 1998Natur.392..164M.
- ↑ Vasisht, V. V.; Saw, S.; Sastry, S. (2011). "Liquid-Liquid Critical Point in Supercooled Silicon". Nat. Phys. 7 (7): 549–555. doi:10.1038/nphys1993. Bibcode: 2011NatPh...7..549V.
- ↑ Katayama, Y.; Mizutani, T.; Utsumi, W.; Shimomura, O.; Yamakata, M.; Funakoshi, K. (2000). "A First-Order Liquid-Liquid Phase Transition in Phosphorus.". Nature 403 (6766): 170–173. doi:10.1038/35003143. PMID 10646596. Bibcode: 2000Natur.403..170K.
- ↑ Cadien, A.; Hu, Q. Y.; Meng, Y.; Cheng, Y. Q.; Chen, M. W.; Shu, J. F.; Mao, H. K.; Sheng, H. W. (2013). "First-Order Liquid-Liquid Phase Transition in Cerium.". Phys. Rev. Lett. 110 (12): 125503. doi:10.1103/PhysRevLett.110.125503. PMID 25166820. Bibcode: 2013PhRvL.110l5503C.
- ↑ Yen, F.; Chi, Z. H.; Berlie, A.; Liu, X. D.; Goncharov, A. F. (2015). "Dielectric Anomalies in Crystalline Ice: Indirect Evidence of the Existence of a Liquid−Liquid Critical Point in H2O.". J. Phys. Chem. C 119 (35): 20618–20622. doi:10.1021/acs.jpcc.5b07635.
- ↑ O. Gomes, Gabriel; Stanley, H. Eugene; Souza, Mariano de (2019-08-19). "Enhanced Grüneisen Parameter in Supercooled Water" (in en). Scientific Reports 9 (1): 1–8. doi:10.1038/s41598-019-48353-4. ISSN 2045-2322. https://www.nature.com/articles/s41598-019-48353-4.
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