Drozd-Rzoska A, Rzoska S J, Zioło J, Jadzyn J
August Chelkowski Institute of Physics, Silesian University, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
Phys Rev E Stat Nonlin Soft Matter Phys. 2001 May;63(5 Pt 1):052701. doi: 10.1103/PhysRevE.63.052701. Epub 2001 Apr 13.
Results presented give evidence of the existence of quasicritical, fluidlike behavior in the isotropic phase of 4-cyano-4-pentyl-biphenyl (5CB) for frequencies ranging from the static to the ionic-dominated [low-frequency (LF)] region. Despite the boost of dielectric permittivity on lowering the frequency below 1 kHz, values of the isotropic-nematic transition discontinuity (approximately 1.1 K) and the critical exponent alpha (approximately 0.5) remain constant. It is shown that the contribution from residual ionic impurities is a linear function of temperature in the critical, prenematic fluctuation-dominated region. The validity of the fluidlike and critical behavior for LF dielectric permittivity confirmed results of a derivative analysis of the experimental data: d(epsilon)/dT proportional to (T-T*)(-alpha), originally proposed for critical mixtures. Results of a preliminary test in the isotropic phase of 4-decyl-4'-isothiocyanatobiphenyl (10BT), on approaching the smectic-E phase, may indicate a general validity of results obtained.
给出的结果证明，在4-氰基-4-戊基联苯（5CB）的各向同性相中，对于从静态到离子主导的[低频（LF）]区域的频率，存在准临界、类似流体的行为。尽管在频率低于1 kHz时介电常数有所增加，但各向同性-向列相转变的不连续性值（约1.1 K）和临界指数α（约0.5）保持不变。结果表明，在临界的、向列相前涨落主导的区域，残余离子杂质的贡献是温度的线性函数。低频介电常数的类似流体和临界行为的有效性证实了对实验数据的导数分析结果：d(ε)/dT ∝ (T - T*)(-α)，这最初是针对临界混合物提出的。在4-癸基-4'-异硫氰酸联苯（10BT）的各向同性相中接近近晶-E相时的初步测试结果，可能表明所获得结果具有普遍有效性。
