Institute of High Pressure Physics, Polish Academy of Sciences, X-PressMatter Lab, ul. Sokołowska 29/37, 01-142, Warsaw, Poland.
Faculty of Advanced Technologies and Chemistry, Military University of Technology, ul. gen. Sylwestra Kaliskiego 2, 00-908, Warsaw, Poland.
Eur Phys J E Soft Matter. 2022 Sep 8;45(9):74. doi: 10.1140/epje/s10189-022-00228-9.
The report shows the temperature behavior of the real part of dielectric permittivity in the static (dielectric constant) and low-frequency (LF) domains in bulk samples of 11CB and its BaTiO-based nanocolloids. The study covers the isotropic liquid (I), nematic (N), smectic A (SmA), and solid crystal (Cr) phases. For each phase, the dominance of pretransitional fluctuations, significantly moderated by nanoparticles, is shown. The authors consider separate focuses on the dielectric constant [Formula: see text] evolution in the static domain, yielding mainly response from permanent dipole moment and its arrangement, and in the low-frequency (LF) domain [Formula: see text] (where [Formula: see text] is for the real part of dielectric permittivity in the LF domain), which is associated solely with ionic-related polarization mechanisms. All of these led to new experimental evidence concerning I-N, N-SmA, and SmA-solid transitions, focusing on the strength and extent of pretransitional effects, critical exponents, and phase transitions discontinuities. The strong evidence for pretransitional effects near the SmA-Cr transition is notable, particularly regarding [Formula: see text]. Studies are supplemented by the discussion of DC electric conductivity-a parameter also related to the LF domain. Finally, the validity of the relation [Formula: see text] (where f stands for frequency, and A is a constant parameter), often used for discussing dielectric spectra in LC compound and its nanocolloids in the LF domain, is examined.
该报告展示了 11CB 及其基于 BaTiO3 的纳米胶体的体相样品在静态（介电常数）和低频（LF）区域中实部介电常数的温度行为。该研究涵盖各向同性液体（I）、向列（N）、近晶 A（SmA）和固态晶体（Cr）相。对于每种相，都显示了预相变涨落的主导地位，而纳米颗粒显著缓和了这种主导地位。作者分别关注了静态域中的介电常数 [Formula: see text] 演变，这主要反映了永久偶极矩及其排列的响应，以及低频（LF）域中的 [Formula: see text]（其中 [Formula: see text] 是 LF 域中介电常数的实部），这仅与离子相关的极化机制有关。所有这些都提供了有关 I-N、N-SmA 和 SmA-固态相变的新实验证据，重点关注预相变效应的强度和程度、临界指数和相变不连续性。在 SmA-Cr 相变附近存在强烈的预相变效应的证据非常值得注意，特别是关于 [Formula: see text]。研究还通过讨论与 LF 域相关的直流电导率-一个参数来进行补充。最后，检查了在 LF 域中经常用于讨论 LC 化合物及其纳米胶体介电谱的关系 [Formula: see text]（其中 f 代表频率，A 是一个常数参数）的有效性。
