AI 中文总结
本研究探究BaTiO₃纳米粒子对5CB液晶悬浮液介电性能的影响，发现其浓度会非单调改变中间相-各向同性相转变温度，高浓度粒子通过空间电荷积累调控离子传输与介电机制。
AI 中文摘要
本研究聚焦于向列相液晶5CB与不同浓度（0至10 wt.%）、平均尺寸24 nm的铁电BaTiO₃纳米粒子构成的悬浮液的介电响应与电导率机制。研究发现，纳米粒子的加入会显著影响悬浮液的介电常数大小、各向异性及介电损耗。在对应中间相状态的较低温度下，悬浮液的各向异性介电常数呈现明显的温度依赖性；在对应各向同性相的较高温度下，该依赖性依然存在。中间相-各向同性相转变温度随BaTiO₃纳米粒子浓度的变化呈非单调关系。随着温度升高，纯液晶的电容和电阻均增大，含低浓度BaTiO₃纳米粒子的悬浮液也呈现相同变化。由于纳米粒子壳层内空间电荷的积累，高浓度BaTiO₃纳米粒子会通过促进离子-电子屏蔽的形成，强烈影响离子传输，该效应会改变悬浮液的介电性能与传导机制，进而导致中间相-各向同性相转变温度随纳米粒子浓度呈非单调依赖关系。
英文摘要
This work is devoted to the mechanisms of dielectric response and electric conductivity of suspensions consisting of the nematic liquid crystal 5CB with different concentrations (from 0 to 10 wt.%) of ferroelectric BaTiO_3 nanoparticles with an average size of 24 nm. We revealed that the incorporation of nanoparticles influences significantly the dielectric permittivity magnitude and anisotropy, as well as dielectric losses of the suspension. A pronounced temperature dependence of the anisotropic dielectric permittivity of the suspensions was found at lower temperatures corresponding to the mesophase state; but it is also present at higher temperatures corresponding to the isophase. The dependence of the mesophase-isophase transition temperature on the concentration of BaTiO_3 nanoparticles appeared nonmonotonic. With increasing temperature, both the capacitance and the electrical resistance of the pure liquid crystal increase, as well as it increases in the suspensions with small concentration of BaTiO_3 nanoparticles. Due to space charge accumulation in the shells of nanoparticles, larger concentrations of BaTiO_3 nanoparticles influence strongly the ionic transport by promoting the formation of ionic-electronic screening. This effect modifies the dielectric properties and conduction mechanisms of the suspension, leading to the nonmonotonic dependence of the mesophase - isophase transition temperature versus the nanoparticle concentration.
Comments21 pages, 7 figures
