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Byl připraven a prostudován nový typ dimeru na bázi kapalně krystalických molekul zahnutého tvaru, které jsou spojeny alkylovou spojkou v centrální části. Byla zjištěna možnost přepínání v elektrickém poli. Celý 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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Ferroelektrické materiály jsou známé svou velkou dielektrickou permitivitou. Ukazuje se, že mikrostruktura materiálu, obzvláště feroelektrická doménová rozhraní, může mít velký vliv na dielektrickou odezvu materiálu. V této studii jsme se zaměřili na různé konfigurace doménových rozhraní v multiferoelectrickém materiaĺu 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.
Celý 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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Česká televize ČT24, 2.7.2018.
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