P. Perkowski
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View article: The balance between paraelectricity and ferroelectricity in non-chiral smectic homologs
The balance between paraelectricity and ferroelectricity in non-chiral smectic homologs Open
Non-chiral liquid crystals (LCs) exhibiting ferroelectricity, distinguished by their dynamic responsiveness to external stimuli and high spontaneous polarization, provide renewed impetus for research into this area of soft matter and open …
View article: Dielectric Modes in Antiferroelectric and Ferroelectric Liquid Crystals in a Pure Enantiomeric Version and a Racemic Mixture
Dielectric Modes in Antiferroelectric and Ferroelectric Liquid Crystals in a Pure Enantiomeric Version and a Racemic Mixture Open
The dielectric properties of synclinic (ferroelectric SmC*) and anticlinic (antiferroelectric SmCA*) smectic liquid crystals composed of molecules of one chiral version (S) are presented and compared with properties of racemic mixture (R, …
View article: Polar Nematic Phases with Enantiotropic Ferro- and Antiferroelectric Behavior
Polar Nematic Phases with Enantiotropic Ferro- and Antiferroelectric Behavior Open
The recent discovery of a new ferroelectric nematic (NF) liquid crystalline phase became of utmost interest for the liquid crystal (LC) and the whole soft and condensed matter fields. Contrary to the previously known ferroelectric LC mater…
View article: The Influence of the Molecular Structure of Compounds on Their Properties and the Occurrence of Chiral Smectic Phases
The Influence of the Molecular Structure of Compounds on Their Properties and the Occurrence of Chiral Smectic Phases Open
We have designed new chiral smectic mesogens with the -CH2O group near the chiral center. We synthesized two unique rod-like compounds. We determined the mesomorphic properties of these mesogens and confirmed the phase identification using…
View article: Fluorinated esters with a very broad temperature range of the antiferroelectric phase
Fluorinated esters with a very broad temperature range of the antiferroelectric phase Open
Antiferroelectricity is a desirable property of liquid crystalline materials. Therefore, we synthesised and studied two new chiral rod-like mesogens with a molecular core based on two biphenyls connected via ester linkage, with the phenyl …
View article: Influence of the molecular structure of compounds with terminal isothiocyanate group on the induction of the smectic A phase: Part II
Influence of the molecular structure of compounds with terminal isothiocyanate group on the induction of the smectic A phase: Part II Open
The influence of the structure of compounds having terminal isothiocyanate group in binary mixtures with compounds having terminal alkyl chains on the induction of the smectic A phase is shown. Compounds with a triple bond in the molecular…
View article: Ferroelectricity in a nematic liquid crystal under a direct current electric field
Ferroelectricity in a nematic liquid crystal under a direct current electric field Open
We investigated the influence of the DC electric field on the electrical and optical properties of a liquid crystal compound 4-(4-nitrophenoxycarbonyl)phenyl 2,4-dimethoxybenzoate, known as RM734, exhibiting a ferroelectric nematic phase.
View article: Low-pass RC filter modified by liquid crystal exhibiting one Debye relaxation - theoretical approach
Low-pass RC filter modified by liquid crystal exhibiting one Debye relaxation - theoretical approach Open
The solid dielectrics used in the capacitors exhibit rather high-frequency relaxations. This means that in the radio-frequency range, the capacitors exhibit a constant capacity. When a liquid crystal is put into the capacitors, it is obser…
View article: A Pilot Study of Influence of Endurance Training on the Prooxidative and Antioxidant Status of Women after Breast Cancer
A Pilot Study of Influence of Endurance Training on the Prooxidative and Antioxidant Status of Women after Breast Cancer Open
The objective of this study was to assess the effect of 8-week long endurance training on the prooxidative–antioxidative status of plasma in women treated for breast cancer. The participants of the study were 12 women after radical mastect…
View article: The parasitic effects in high-frequency dielectric spectroscopy of liquid crystals – the review
The parasitic effects in high-frequency dielectric spectroscopy of liquid crystals – the review Open
Dielectric (impedance) spectroscopy of liquid crystals is a powerful experimental technique. It is especially essential because liquid crystals in many applications are still controlled by the electric field. In this paper, the problems wi…
View article: The parasitic effects in high-frequency dielectric spectroscopy of liquid crystals – the review
The parasitic effects in high-frequency dielectric spectroscopy of liquid crystals – the review Open
Dielectric (impedance) spectroscopy of liquid crystals is a powerful experimental technique. It is especially essential because liquid crystals in many applications are still controlled by the electric field. In this paper, the problems wi…
View article: The parasitic effects in high-frequency dielectric spectroscopy of liquid crystals – the review
The parasitic effects in high-frequency dielectric spectroscopy of liquid crystals – the review Open
Dielectric (impedance) spectroscopy of liquid crystals is a powerful experimental technique. It is especially essential because liquid crystals in many applications are still controlled by the electric field. In this paper, the problems wi…
View article: The evolution of the molecular relaxation parameters described by the Cole–Cole model at the isotropic-nematic phase transition
The evolution of the molecular relaxation parameters described by the Cole–Cole model at the isotropic-nematic phase transition Open
This paper presents the dielectric properties of the isotropic liquid and nematic phase at the phase transition. One strong molecular relaxation is observed in both phases. It is interpreted as related to the relaxation around a short mole…
View article: Threshold voltage decrease in a thermotropic nematic liquid crystal doped with graphene oxide flakes
Threshold voltage decrease in a thermotropic nematic liquid crystal doped with graphene oxide flakes Open
We report a threshold voltage decrease in a nematic liquid crystal compound, 4-cyano-4′-pentylbiphenyl (5CB), doped with graphene oxide (GO) flakes at a concentration of 0.05–0.3 wt %. The threshold voltage decrease was observed at the sam…
View article: Report on the XXIII Czech–Polish seminar: structural and ferroelectric phase transitions, May 21–25, 2018, Kouty, Czech Republic
Report on the XXIII Czech–Polish seminar: structural and ferroelectric phase transitions, May 21–25, 2018, Kouty, Czech Republic Open
The Czech–Polish Seminar entitled ‘Structural and Ferroelectric Phase Transitions’ has a long-standing tradition. It has been organised for almost 40 years as a result of a strong cooperation betwe...