Caerels J, Glorieux C, Thoen J
Laboratorium voor Akoestiek en Thermische Fysica, Department Natuurkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium.
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Mar;65(3 Pt 1):031704. doi: 10.1103/PhysRevE.65.031704. Epub 2002 Feb 8.
Using a recently developed photopyroelectric ac calorimetric technique we investigate two binary liquid crystal mixtures with so-called injected smectic-A phases. Characteristic of these systems is the occurrence of nematic-to-smectic-A transition lines in the phase diagram of mixtures of pure compounds having only a nematic phase. The two binary systems are pentylcyanobiphenyl with either 4-n-propylcyclohexyl-carboxylate or 4-n-pentylphenyl 4(')-n-pentyloxybenzoate. Both these systems have domelike smectic-A ranges with narrow nematic ranges at the top. Near the top the N-SmA transitions are of first order and are crossing over to second order at a tricritical point on either side of the top with the increasing width of the nematic range. The obtained critical exponents are almost completely Fisher renormalized because of the strong concentration dependence of the nematic-to-smectic-A transition temperatures.
我们使用最近开发的光热释电交流量热技术，研究了两种具有所谓注入型近晶A相的二元液晶混合物。这些体系的特征是，在仅具有向列相的纯化合物混合物的相图中出现向列相到近晶A相的转变线。这两种二元体系是戊基氰基联苯与4-正丙基环己基羧酸盐或4-正戊基苯基4（′）-正戊氧基苯甲酸盐。这两种体系都具有穹顶状的近晶A相范围，顶部有狭窄的向列相范围。在顶部附近，N-SmA转变是一级的，并且随着向列相范围宽度的增加，在顶部两侧的三临界点处转变为二级。由于向列相到近晶A相转变温度对浓度的强烈依赖性，所获得的临界指数几乎完全是费希尔重整化的。
