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Department of Dielectrics

Institute of Physics of the Czech Academy of Sciences


group Dielectric and IR spectroscopy science Dielectric and IR spectroscopy group THz and pump-probe science THz science and technology group Photon and neutron scattering group Light and neutron scattering group Theory Theory and
simulations
group Solid materials science Solid-state materials science group Liquid crystal material science Liquid crystals

About us

Main activities of Department of Dielectrics cover experimental and theoretical investigations of high-permittivity insulators like liquid crystals, ferroelectrics, multiferroics, piezoelectrics, semiconductor nanostructures, and low-loss materials.

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Photo of people of Dielectrics
Our mission: Understanding the materials for which the frequency dependence of dielectric function can be probed by capacitance, waveguide or optical techniques. Experimental research in the Department of Dielectrics is mostly based on dielectric, infrared, time-domain THz, Raman and neutron spectroscopy, but also calorimetry, nonlinear optics and scanning probe microscopy measurements. The information on the core research activities organized within our six principal research groups can be accessed through the following links:

The most significant fresh scientific results of our deparment are listed in the section Highlights.

News & Public

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18.05.2020 Award

Karel Tesař among winners of the Materials Today Cover Competition 2019

Karel's photo taken by an electron microscope succeeded in the Materials Today Cover Competition 2019. So-called 'Uncovered article' about biodegradable magnesium implants, closely related to the winning photo, has been recently published in Materials Today.

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28.02.2020 Research

A new class of ferroelectric materials suggested

Using strain engineering, researchers obtained a transitional ferroelectric state in BaTiO3, which exhibits high piezoelectric and dielectric coefficients in a wide temperature range [1].

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09.01.2020 Research

New material for 5G mobile networks

Stanislav Kamba, Veronica Goian and Christelle Kadlec, in collaboration with Prof. D. G. Schlom from the Cornell University and other American and German colleagues, succeeded in developing a new material for mobile network of the 5th generation.

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Upcoming Seminars & Workshops

Seminars to be announced.

Latest Highlights
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New material for 5G mobile networks

Epitaxial strained thin films of (SrTiO3)n-1(BaTiO3)1SrO were found to be a promising new material for mobile network of the 5th generation [Nature Mater. 19, 176 (2020)].

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Organic nanotubes created from mesogenic lactic acid derivatives

We found a facile route how to prepare nanotubes from rod-like mesogens dissolved in typical organic solvents. For selected types of chiral rod-like molecules, both enantiomers as well as the racemic mixtures, the nanotubes are formed by slow evaporation from a solution, regardless the solvent, concentration or deposition type. Obtained supramolecular assemblies were studied using various experimental techniques and nanotubes of 50-60 nm diameter described. We proposed rolling-up mechanism related to the surface tension difference at the opposite layer surfaces.

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Mesoscopic polarization dynamics and two ferroelectric sublattices in the uniaxial tetragonal tungsten bronze (SrxBa1−x)Nb2O6

The high-frequency dielectric behavior of uniaxial tungsten-bronze strontium barium niobate crystals with various Sr/Ba ratios have been studied in order to thoroughly understand the evolution of the relaxation dynamics across the ferroelectric phase transition. We showed that the dielectric response along the polar axis consists of three relaxations corresponding to polarization mechanisms related to several correlation lengths of mesoscopic order and that they are closly associated with two different ferroelectric subsystems.in the structure [1].

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Changes in spin and lattice dynamics induced by magnetic and structural phase transitions in multiferroic SrMn7O12

Upon cooling, SrMn7O12 undergoes a series of structural and magnetic phase transitions from cubic to rhombohedral symmetry, and to an incommensurately modulated crystal structure, which is connected with charge and orbital ordering of the Mn cations. We report IR, THz, and Raman spectra of SrMn7O12 ceramics reflecting corresponding changes in the phonon selection rules, including new phonons appearing in spin-order-induced ferroelectric phases [1].

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Raman scattering yields cubic crystal grain orientation

The anisotropy of Raman scattering was applied to determine the orientation of individual microcrystal grains, as small as a few µm, of GaV4S8 polycrystalline compound. This was possible by measuring polarised Raman spectra as a function of rotation of the sample along the laser direction. On comparing the resulting set of spectra with a computer simulation for particular symmetries, the orientation of the crystal grains could of the determined with good precision.

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Soft mode driven local ferroelectric transition in lead-based relaxors

Analysis of IR and THz spectra using Bruggeman effective medium approach revealed that the mesoscopic structure of Pb(Mg1/3Nb2/3)O3 and Pb(Mg1/3Ta2/3)O3 consists of dynamic randomly oriented uniaxially anisotropic polar nanoregions with harder transverse optical polar modes in the direction along the local dipoles [1,2].

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Degenerate (identity) chemical reactions in ferro­elastic crystals

The work points to reconsideration of degenerate chemical reactions because of the chemical reactions which take place in a solid phase where the orientation of the substituting molecules is maintained. The work points to the examples of a ferroelastic switching which is accompanied by braking and reestablisment of chemical bonds. The article suggests that the definition of the degenerate chemical reactions might distinguish the reactions where the truly identical molecules are formed from those ones where the resulting molecules are enantiomers or enatiomorphs in case of domains.

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Latest Key Articles

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N. M. Dawley, E. J. Marksz, A. M. Hagerstrom, G. H. Olsen, M. E. Holtz, V. Goian, C. Kadlec, J. Zhang, X. Lu, J. A. Drisko, R. Uecker, S. Ganschow, C. J. Long, J. C. Booth, S. Kamba, C. J. Fennie, D. A. Muller, N. D. Orloff, and D. G. Schlom,

Targeted chemical pressure yields tuneable millimetre-wave dielectric

Nature Materials 19, 176 (2020).
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A. S. Everhardt, T. Denneulin, A. Gruenebohm, Y.-T. Shao, P. Ondrejkovic, S. Zhou, N. Domingo, G. Catalan, J. Hlinka, J.-M. Zuo, S. Matzen, B. Noheda

Temperature-independent giant dielectric response in transitional BaTiO3 thin films

Appl. Phys. Rev. 7, 011402 (2020).
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S. Skiadopoulou, M. Retuerto, F. Borodavka, C. Kadlec, F. Kadlec, M. Míšek, J. Prokleška, Z. Deng, X. Tan, C. Frank, J. A. Alonso, M. T. Fernandez-Diaz, M. Croft, F. Orlandi, P. Manuel, E. McCabe, D. Legut, M. Greenblatt, S. Kamba,

Structural, magnetic, and spin dynamical properties of the polar antiferromagnets Ni3-xCoxTeO6(x=1,2)

Phys. Rev. B 101, 014429 (2020).
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K. Tesař, J. Maňák, P. Vaněk, J. Drahokoupil, J. Hlinka,

Microstructure and micromechanical properties of GaV4S8 ceramics prepared by single-step solid state synthesis

Ceram. Int. 46, 7045 (2020).
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P. Kužel and H. Němec,

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge-Carrier Transport

Adv. Opt. Mater. 8, 1900623 (2020).
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M. Šmahel, A. Poryvai, Y. Xiang, D. Pociecha, T. Troha, V. Novotná, J. Svoboda, and M. Kohout,

Photosensitive bent-core nematic liquid crystals with various linking units in the side arms: Structure-properties relationships

J. Mol. Liq. 306, 112743 (2020).

Last update: 18 May 2020 (admin)