Drozd-Rzoska Aleksandra, Łoś Joanna, Rzoska Sylwester J
Institute of High Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland.
Nanomaterials (Basel). 2025 Apr 13;15(8):597. doi: 10.3390/nano15080597.
This report discusses the impact of nanoparticles on glass-forming systems composed of a liquid crystalline (LC) mixture E7 and paraelectric BaTiO particles (d≈50 nm, globular), tested via broadband dielectric spectroscopy. In the isotropic phase, critical changes in the dielectric constant are shown. They are related to the weakly discontinuous nature of the isotropic-nematic transition. In the nematic phase, two primary relaxation times/processes and DC electric conductivity are considered, down to the glass temperature Tg. The prevalence of portrayals via the 'double exponential' MYEGA equation and the critical & activated Drozd-Rzoska relation for dynamic properties are shown. For the primary loss curve, critical-like changes of its maximum (peak) are evidenced: εpeak″∝1/T-Tg* for Tg<T<Tg+25 K, where Tg*<Tg denotes the extrapolated singular temperature. Dielectric constant monitoring revealed the permanent arrangement of rod-like LC molecules by nanoparticles' endogenic impact in the nematic phase. The heuristic model regarding this unique behavior is presented. It considers a hypothetical link between the glass transition and a hidden near-critical discontinuous phase transition, uniquely avoiding a symmetry change. The uniaxiality of LC molecules enables the detection of critical-like features when approaching the glass transition, hypothetically associated with a specific 'amorphous' phase transition.
本报告讨论了纳米颗粒对由液晶（LC）混合物E7和顺电BaTiO颗粒（d≈50 nm，球形）组成的玻璃形成系统的影响，通过宽带介电谱进行测试。在各向同性相中，显示出介电常数的临界变化。它们与各向同性-向列相转变的弱不连续性质有关。在向列相中，考虑了两个主要弛豫时间/过程以及直流电导率，直至玻璃化温度Tg。展示了通过“双指数”MYEGA方程以及动态特性的临界与活化Drozd-Rzoska关系进行描述的普遍性。对于初级损耗曲线，其最大值（峰值）出现了类似临界的变化：对于Tg<T<Tg+25 K，εpeak″∝1/T-Tg*，其中Tg*<Tg表示外推的奇异温度。介电常数监测揭示了在向列相中纳米颗粒的内生影响导致棒状LC分子的永久排列。提出了关于这种独特行为的启发式模型。它考虑了玻璃化转变与隐藏的近临界不连续相变之间的假设联系，独特地避免了对称性变化。LC分子的单轴性使得在接近玻璃化转变时能够检测到类似临界的特征，假设与特定的“非晶”相变相关。
