Madhavan Unni P K
Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
J Chem Phys. 2006 Mar 28;124(12):124510. doi: 10.1063/1.2180785.
We report preliminary experiments on the ternary-liquid mixture, methyl ethyl ketone (MEK)+water (W)+secondary butyl alcohol (sBA)--a promising system for the realization of the quadruple critical point (QCP). The unusual tunnel-shaped phase diagram shown by this system is characterized and visualized by us in the form of a prismatic phase diagram. Light-scattering experiments reveal that (MEK+W+sBA) shows near three-dimensional-Ising type of critical behavior near the lower critical solution temperatures, with the susceptibility exponent (gamma) in the range of 1.217< or =gamma< or =1.246. The correlation length amplitudes (xio) and the critical exponent (nu) of the correlation length (xi) are in the ranges of 3.536< or =xio < or =4.611 A and 0.619< or =nu< or =0.633, respectively. An analysis in terms of the effective susceptibility exponent (gammaeff) shows that the critical behavior is of the Ising type for MEK concentrations in the ranges of 0.1000< or =X< or =0.1250 and X> or =0.3000. But, for the intermediate range of 0.1750< or =X<0.3000, the system shows a tendency towards mean-field type of critical behavior. The advantages of the system (MEK+W+sBA) over the system (3-methylpyridine+water+heavy water+potassium Iodide) for the realization of a QCP are outlined.
我们报告了关于三元液体混合物甲乙酮（MEK）+水（W）+仲丁醇（sBA）的初步实验，该混合物是实现四重临界点（QCP）的一个有前景的体系。我们以棱柱形相图的形式对该体系呈现的异常隧道形相图进行了表征和可视化。光散射实验表明，（MEK+W+sBA）在较低临界溶液温度附近表现出近三维伊辛型临界行为，其磁化率指数（γ）在1.217≤γ≤1.246范围内。关联长度振幅（ξ₀）和关联长度（ξ）的临界指数（ν）分别在3.536≤ξ₀≤4.611 Å和0.619≤ν≤0.633范围内。根据有效磁化率指数（γeff）进行的分析表明，对于MEK浓度在0.1000≤X≤0.1250和X≥0.3000范围内，临界行为属于伊辛型。但是，对于0.1750≤X＜0.3000的中间范围，该体系表现出向平均场型临界行为的趋势。概述了体系（MEK+W+sBA）相对于体系（3-甲基吡啶+水+重水+碘化钾）在实现QCP方面的优势。
