Jožef Stefan Institute

About: Jožef Stefan Institute is a facility organization based out in Ljubljana, Slovenia. It is known for research contribution in the topics: Liquid crystal & Dielectric. The organization has 3828 authors who have published 12614 publications receiving 291025 citations.

Structure studies of the nematic phase formed by bent-core molecules.

Abstract: In recent years there are several reports showing that bent-core mesogenic molecules are able to form biaxial nematic phase in which molecular rotation around the long molecular axis is strongly hindered. The x-ray pattern with azimuthally split signals at low angle region of diffraction is usually given as evidence for the biaxial nematic phase. We show experimentally and theoretically that such x-ray pattern is due to the local smectic-$C$ fluctuations (``cybotactic'' groups) in the uniaxial nematic phase.

Surface Phase Transitions in BiFeO3 Below Room Temperature

Abstract: We combine a wide variety of experimental techniques to analyze two heretofore mysterious phase transitions in multiferroic bismuth ferrite at low temperature. Raman spectroscopy, resonant ultrasound spectroscopy, electron paraelectric resonance, x-ray lattice constant measurements, conductivity and dielectric response, and specific heat and pyroelectric data have been collected for two different types of samples: single crystals and, in order to maximize surface/volume ratio to enhance surface phase transition effects, BiFeO${}_{3}$ nanotubes were also studied. The transition at $T$ $=$ 140.3 K is shown to be a surface phase transition, with an associated sharp change in lattice parameter and charge density at the surface. Meanwhile, the 201 K anomaly appears to signal the onset of glassy behavior.