Low-frequency relaxation modes in ferroelectric liquid crystal/gold nanoparticle dispersion: impact of nanoparticle shape

• Published in: Liquid crystals Vol. 43; no. 11; pp. 1536 - 1547
• Main Authors: Podgornov, F. V., Wipf, R., Stühn, B., Ryzhkova, A. V., Haase, W.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 01.09.2016; Taylor & Francis Ltd
• Subjects: Crystallography; dielectric spectroscopy; Dispersion; electric double layers; Electrodes; Ferroelectric liquid crystals; Ferroelectricity; Ferroelectrics; Gold; gold nanoparticles; Indium tin oxide; Liquid crystals; Nanoparticles; Nanostructure; relaxation modes; Spectrum analysis
• ISSN: 0267-8292; 1366-5855
• DOI: 10.1080/02678292.2016.1186754

Low-frequency (1 mHz-100 Hz) dielectric relaxation modes were experimentally studied in ferroelectric liquid crystal (FLC)/gold nanoparticles (nanospheres and nanorods) dispersion. It was demonstrated that the dielectric spectra of nanodispersion are strongly influenced by the shape of nanoparticles. Using different formalisms of the impedance spectroscopy, three possible low-frequency relaxation processes were found in the dispersions and the pure FLC. Due to the electrical double layers (EDLs) near nanoparticles and the alignment layers, one can observe the relaxation of the EDL polarisation around the nanoparticles (Schwarz's relaxation) and near the driving indium tin oxide (ITO) electrodes (electrode polarisation). The other possible relaxation process is interfacial polarisation (Maxwell-Wagner mode) in which the frequency is unaffected by the nanoparticles. It was shown that Schwarz's relaxation frequency strongly depended on the shape and size of the nanoparticles. Moreover, dispersion of nanoparticles significantly reduced direct current conductivity of the FLC mixture.