Density Measurements of Alloys Exhibiting the Re-Entrant Nematic Phase
Density Measurements of Alloys Exhibiting the Re-Entrant Nematic Phase
复制标题
具有再入向列相的合金的密度测量
DOI：
10.1080/01406568008072514
复制
发表时间：
1980
影响因子：
0.7
通讯作者：
P. Cladis
中科院分区：
文献类型：
--
作者：
F. Bouchet;P. Cladis
本文测量了60CB(氰基己氧基联苯)和80CB(氰基辛氧基联苯)混合物的密度p随温度和组成的变化。在一定的温度T和组成C的范围内，这些混合物表现出重入向列相，p(T)不是线性的，但在较低的温度下呈现出接近线性的趋势。结果表明，近晶A相的等压可压缩性仅在近晶A相附近得到βS=7.71±0.06×10−4g/cc/°C，向列相和再入向列相的βN=8.03±0.15±10−4gms/cc/°C。发现1/p与C呈线性关系，这意味着分子在近晶A相相邻层中的部分嵌入，以确保合金化时，60CB和80CB所占的体积不超过纯化合物的体积。最后，在近晶A重入向列相转变附近的非常精确的测量表明，过渡前密度有异常大的增加。
Abstract Measurements of the density, p, of mixtures of 60CB (cyanohexyloxybiphenyl) and 80CB (cyanooctyloxybiphenyl) are presented as a function of temperature and composition. In a certain range of temperature, T, and composition, C, these mixtures exhibit the re-entrant nematic phase, p (T) is not linear but exhibits an approach to linearity at lower temperatures. Consequently the isobaric compressibility is evaluated only in the vicinity of the smectic A phase and is found to be βS =7.71 ± 0.06 × 10−4 g/cc/°C for the smectic A phase and βN = 8.03 ± 0.15 ± 10−4 gms/cc/°C for the nematic and reentrant nematic phases. 1/p is found to depend linearly on C implying the partial intercalation of molecules in neighboring layers of the smectic A phase to ensure that, when alloyed, 60CB and 80CB occupy no more than their volume in pure compounds. Finally, very precise measurements in the vicinity of the smectic A re-entrant nematic transition show an anomalously large pretransitional increase in the density of ...