title: Nanoparticle-induced twist-grain boundary phase.
abstract: By means of high-resolution ac calorimetry and polarizing optical microscopy, it is demonstrated that surface-functionalized spherical CdSSe nanoparticles induce a twist-grain boundary phase when dispersed in a chiral liquid crystal. These nanoparticles can effectively stabilize the one-dimensional lattice of screw dislocations, thus establishing the twist-grain boundary order between the cholesteric and the smectic-A phases. A Landau-de Gennes-Ginzburg model is used to analyze the impact of nanoparticles on widening the temperature range of molecular organizations possessing a lattice of screw dislocations. We show that in addition to the defect-core-replacement mechanism, the saddle-splay elasticity may also play a significant role.
authors.affiliation: Condensed Matter Physics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia.
authors.forename: Maja
authors.initials: M
authors.lastname: Trček
authors.affiliation: Condensed Matter Physics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia and Department of Physics, National and Kapodistrian University of Athens, 15784 Zografou, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Cordoyiannis
authors.affiliation: Biomolecular Physics Laboratory, National Centre for Scientific Research "Demokritos," 15310 Aghia Paraskevi, Greece.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Tzitzios
authors.affiliation: Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia.
authors.forename: Samo
authors.initials: S
authors.lastname: Kralj
authors.affiliation: Biomolecular Physics Laboratory, National Centre for Scientific Research "Demokritos," 15310 Aghia Paraskevi, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Nounesis
authors.affiliation: Department of Physics, National and Kapodistrian University of Athens, 15784 Zografou, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Lelidis
authors.affiliation: Condensed Matter Physics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia and Jožef Stefan International Postgraduate School, 1000 Ljubljana, Slovenia.
authors.forename: Zdravko
authors.initials: Z
authors.lastname: Kutnjak
mesh_terms: D004548:Elasticity; D050866:Liquid Crystals / Q000737:chemistry; D008962:Models, Theoretical; D053758:Nanoparticles / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics