Radio Praha in English, 4.5.2018.
Experts from the Institute of...
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Selected results of department 12
Structurally new type of dimers composed of bent-core molecules connected through their central cores has been prepared and studied. The switching behaviour in the applied electric field is reported. The whole text »
The high-frequency dielectric response of the uniaxial strontium barium niobate (SrxBa1−xNb2O6) crystals with 81% of Sr (x = 0.81) was studied from 1 kHz to 30 THz along the polar axis in a wide temperature interval [E. Buixaderas et al, Sci. Rep. 7, 18034 (2017)]. Relaxor properties were observed in the complex dielectric response and four main excitations were ascertained below the phonon frequencies. These fast polarization mechanisms take place at THz, GHz and MHz ranges and show different temperature evolution.
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Ferroelectric materials are known for their exceptionally high dielectric permittivity. It turns out, that important part of it originates from a material's complicated microstructure and in particular from interfaces between ferroelectric domains. In this study we investigate different types of interfaces in a multiferroic BiFeO3 ...
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Analysis of IR and THz spectra using Bruggeman effective medium approach revealed that the mesoscopic structure of Pb(Mg1/3Nb2/3)O3 (PMN) consists of randomly oriented uniaxially anisotropic polar nanodomains with harder transverse optical polar modes in the direction along the local dipoles.
The lowest-frequency phonon of the E symmetry...
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All 212 species of structural phase transitions with a macroscopic symmetry breaking were inspected with respect to the simultaneous occurrence of the ferroelastic, ferroelectric, and ferroaxial properties.
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In rutile the charge carriers form polarons with high effective mass owing to the strong electron-phonon coupling. In this paper we studied ultrafast terahertz photoconductivity in rutile under strong optical excitation.
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We proved that ferroelectric immersed in a liquid influences electric charge distribution at the surface. Therefore ferroelectric coating on bone implant surface promotes bone cell growth and proliferation, healing should be improved [1].
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The dielectric behaviour of the most famous piezoelectric material, Pb(Zr0.52Ti0.48)O3 ceramics, below room temperature is explained by the topology of the sample, and not by intrinsic structural changes.
The whole text »All-organic liquid crystalline radicals with a spin unit in the outer position of a bent-core system
All-organic paramagnetic liquid crystals offer the advantage of a long-range order of liquid crystalline phases and the magnetic properties of the individual molecules. In such systems, the magnetic properties can be modified by phase transition or the application of external fields. In our work paramagnetic all-organic bent-core liquid crystals having the radical-bearing unit (TEMPO) in the terminal position of an elongating side arm are studied.
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A series of papers about discovery of new ferroelectrics using PFM microscopy has recently been published. On the example of strained TiO2 thin films, which exhibit ferroelectric-like hysteresis loops, we have shown that PFM response can come from electrochemical effects like migration of defects.
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