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Papers by Ewa Rysiakiewicz-Pasek

Materials Science- Poland, 2012

NH4H2PO4 nano-composite antiferroelectric materials in porous glass have been studied by means of... more NH4H2PO4 nano-composite antiferroelectric materials in porous glass have been studied by means of dielectric and dilatometric investigations. Dielectric spectroscopy measurements in a wide frequency range are reported here for the first time, for both the antiferro- and paraelectric phases of ammonium dihydrogen phosphate (ADP) embedded in a porous matrix. Low frequency relaxation processes above the phase transition temperature were shown to occur. An investigation of the thermal expansion revealed a negative volume jump at the phase transition point. It was found that the phase transition temperature in ADP crystals embedded in porous glass decreased with the decrease of the mean pore size. The experimentally observed shift of the phase transition temperature is caused by a combination of size and pressure effects.

Glass Physics and Chemistry - GLASS PHYS CHEM-ENGL TR, 2001

The dielectric relaxation properties of porous glasses prepared from sodium borosilicate glasses ... more The dielectric relaxation properties of porous glasses prepared from sodium borosilicate glasses are studied by dielectric spectroscopy over a wide range of frequencies (20 Hz–1 MHz) and temperatures (–100–300°C). The dielectric behavior reflecting the geometric disorder is analyzed within the models describing the non-Debye slowly damped dynamics. It is found that the dielectric response is very sensitive to microstructural and mesostructural features of the porous matrix and the properties of a material filling pores. The response contains information on the dynamics of water molecules in pores, which accounts for the interaction of these molecules with the pore surface.

Physics of the Solid State, 2009

The dielectric properties and electrical conductivity of the composite material, which was pre pa... more The dielectric properties and electrical conductivity of the composite material, which was pre pared by incorporating the P(VDF 60 /Tr 40) copolymer into the porous glass matrix (the average pore diameter is approximately equal to 320 nm), and the bulk sample of the P(VDF 60 /Tr 40) copolymer have been investi gated in the temperature range 290-440 K. It is revealed that the incorporated material is characterized by an increase in the melting temperature and a considerable decrease in the temperature at which the ferroelec tric phase formed in polymer inclusions becomes unstable. It is shown that charge transfer in the composite material occurs predominantly through channels filled with the polymer.

Optical Materials, 1995

Influence of tantalum and niobium oxide on the electrical conductivity of alkali silicate glasses... more Influence of tantalum and niobium oxide on the electrical conductivity of alkali silicate glasses was investigated. The electrical measurements were performed for three types of alkali silicate glasses containing different amounts of tantalum, niobium and alkali. These glasses are promising materials for gradient elements produced by ion-exchange process.

Journal of Porous Materials, 1996

The properties of the porous glasses before and after impregnation with carbon were studied. The ... more The properties of the porous glasses before and after impregnation with carbon were studied. The electrical measurements (ac and do conductivity) were performed to investigate the structure of carbon filler in the pores. Correlation between luminescence and luminescence excitation spectra and the structure of glass was observed and investigated.

Bulletin of the Russian Academy of Sciences: Physics, 2010

The dielectric properties of composite materials prepared by embedding P(VDF60/Tr40) and P(VDF88/... more The dielectric properties of composite materials prepared by embedding P(VDF60/Tr40) and P(VDF88/Te12) polar copolymers in porous glass matrices with a mean flow-through pore diameter of around 320 nm were investigated in the temperature range 200–450 K. Strong dielectric relaxation, the characteristic time of which conformed to the Williams-Landel-Ferry law, was observed in the vicinity of glass transition point T g of an amorphous fraction of polymer inclusions. An increase (≈10 K) in the T g temperature of the amorphous fraction of incorporated polymeric materials was detected.

Journal of Applied Polymer Science, 2004

ABSTRACT

Physics and Chemistry of Glasses, 1996

Luminescent properties of porous silica glasses (PSG) that underwent the procedure of carbon redu... more Luminescent properties of porous silica glasses (PSG) that underwent the procedure of carbon reduction to enhance the intensity of light emission were studied in a wide temperature range. Photoluminescent (PL) quenching and recovery was observed in light soaking experiments. The results of quasistationary and time resolved PL measurements strongly suggest that tunnel transitions of nonequilibrium charge carriers between quantum size silicon clusters are responsible for the observed long lasting light emission.

Materials, 2020

The results of XRD, FTIR and differential scanning calorimetry (DSC) studies of empty porous sili... more The results of XRD, FTIR and differential scanning calorimetry (DSC) studies of empty porous silica matrices filled with binary mixtures of K1–xAgxNO3 (x = 0.05, 0.10) are reported in comparison with those obtained for bulk salts in the temperature range of structural phase transitions. Scanning electron microscopic data of the studied empty macroporous and microporous glasses confirmed differences in the pore morphology associated with the presence of silica gel. Accordingly, XRD and FTIR samples contain crystalline phase of KNO3 and AgNO3. The results of calorimetric investigation of porous glasses filled with binary mixtures of K1–xAgxNO3 (x = 0.05, 0.10) are presented. The results show that in the K1–xAgxNO3 nanocomposites, anomalies associated with phase transitions were detected. An influence of the mean value of pores sizes on the ferroelectric phase transition temperatures of K1–xAgxNO3 nanocrystals embedded into the porous matrices was determined. The impact of pore space s...

Materials Chemistry and Physics, 2020

Abstract Properties of dielectric and magnetic porous matrices and ferroelectrics porous glasses ... more Abstract Properties of dielectric and magnetic porous matrices and ferroelectrics porous glasses based nanocomposites were studied. Two types of modified and unmodified by iron oxides initial sodium borosilicate glasses and obtained from them porous matrices were investigated. The continuous pore structure was observed in porous glasses and additional in iron containing porous glasses inclusions of iron phase were stated. Depending on technological processes the pore diameters were estimated to be between 4 and 60 nm. The effect of structure and composition of investigated materials on electrical properties was discussed. Dynamic Impedance Spectroscopy measurements have revealed reversible. The dc conductivity and relaxation processes related to different types of transport of sodium and iron ions were discussed. The existence of ferroic KNO3 inside pores determines properties of nanocomposite based on porous matrices. The obtained porous dielectric and magnetic matrices can be applied as ferroics and multiferroeics elements.

Journal of Non-Crystalline Solids, 2020

Abstract The iron-bearing sodium borosilicate glasses with different contents of iron were prepar... more Abstract The iron-bearing sodium borosilicate glasses with different contents of iron were prepared by the charge melting method and studied by XRD, TEM, FTIR, Mossbauer and Dynamic Impedance Spectroscopy techniques. An analysis and the transmittance spectra of two-phase sodium borosilicate glasses with different contents of iron oxide were carried out. A usage of the Mossbauer spectroscopy revealed differences between two-phase and porous glasses. In both cases Fe2+ and Fe3+ ions in octahedral and tetrahedral coordination were found, while in the two-phase glasses the significant contribution of magnetite was additionally detected. The activation energy associated with the relaxation processes determined from the electric modulus spectra was found to be in a range between 0.986 eV and 0.729 eV, which is close to the activation energy for dc conductivity. Two different conduction mechanisms were observed and their physical origin was explained. The hopping between two valence states of iron and the sodium ion conduction mechanism was additionally discussed.

Crystals, 2019

The dielectric properties of composite materials prepared by the embedding of ferroelectrics pota... more The dielectric properties of composite materials prepared by the embedding of ferroelectrics potassium dihydrogen phosphate (KDP), cesium dihydrophosphate (CDP), as well as antiferroelectric ammonium dihydrogen phosphate (ADP) into porous glass matrices with an average size of through pores of 7, 46, and 320 nm have been studied. It was found that an increase occurred in the phase transitions temperature (TC) for embedded particles in comparison with corresponding bulk materials. Some possible mechanisms of influence of “restricted geometry” on the Curie temperature are discussed. Estimates of TC shifting as a result of the “pressure effect” caused by elastic stresses in embedded particles as well as the result of bias electric field influence arising due to the piezoelectric effect are made. The possibility of using the tunneling Ising model to explain the experimental results is discussed.

Bulletin of the Russian Academy of Sciences: Physics, 2019

Results are presented from studying the X-ray diffraction, heat capacities, dielectric permittivi... more Results are presented from studying the X-ray diffraction, heat capacities, dielectric permittivities, and coefficients of the volumetric thermal expansion of composite materials obtained by embedding of Rb2ZnCl4 salt into the porous matrices of borosilicate glass with average pore diameters of 46 and 320 nm in the temperature range of 120–350 K. The temperatures of transitions to the incommensurate and ferroelectric phases are determined, along with the freezing temperature of the mobility of domain boundaries in Rb2ZnCl4 particles. A substantial increase in their Curie temperature is observed.

Physics of the Solid State, 2018

Впервые выполнены исследования влияния ограниченной геометрии на теплоемкость и тепловое расширен... more Впервые выполнены исследования влияния ограниченной геометрии на теплоемкость и тепловое расширение композитов триглицинсульфат(TGS)-боросиликатное стекло. Обнаружено уменьшение энтропии и температуры фазового перехода P2 1 ↔ P21/m в компоненте TGS-при уменьшении диаметра пор стекольной матрицы, происходящее при неизменных значениях аномальных величин теплоемкости и коэффициента теплового расширения. Оценки свидетельствуют о небольшом эффекте внутреннего давления на барический коэффициент dTc /d p TGS в композитах. Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта № 16-32-00092 мол_а.

Materials Science- Poland, 2012

NH4H2PO4 nano-composite antiferroelectric materials in porous glass have been studied by means of... more NH4H2PO4 nano-composite antiferroelectric materials in porous glass have been studied by means of dielectric and dilatometric investigations. Dielectric spectroscopy measurements in a wide frequency range are reported here for the first time, for both the antiferro- and paraelectric phases of ammonium dihydrogen phosphate (ADP) embedded in a porous matrix. Low frequency relaxation processes above the phase transition temperature were shown to occur. An investigation of the thermal expansion revealed a negative volume jump at the phase transition point. It was found that the phase transition temperature in ADP crystals embedded in porous glass decreased with the decrease of the mean pore size. The experimentally observed shift of the phase transition temperature is caused by a combination of size and pressure effects.

Glass Physics and Chemistry - GLASS PHYS CHEM-ENGL TR, 2001

The dielectric relaxation properties of porous glasses prepared from sodium borosilicate glasses ... more The dielectric relaxation properties of porous glasses prepared from sodium borosilicate glasses are studied by dielectric spectroscopy over a wide range of frequencies (20 Hz–1 MHz) and temperatures (–100–300°C). The dielectric behavior reflecting the geometric disorder is analyzed within the models describing the non-Debye slowly damped dynamics. It is found that the dielectric response is very sensitive to microstructural and mesostructural features of the porous matrix and the properties of a material filling pores. The response contains information on the dynamics of water molecules in pores, which accounts for the interaction of these molecules with the pore surface.

Physics of the Solid State, 2009

The dielectric properties and electrical conductivity of the composite material, which was pre pa... more The dielectric properties and electrical conductivity of the composite material, which was pre pared by incorporating the P(VDF 60 /Tr 40) copolymer into the porous glass matrix (the average pore diameter is approximately equal to 320 nm), and the bulk sample of the P(VDF 60 /Tr 40) copolymer have been investi gated in the temperature range 290-440 K. It is revealed that the incorporated material is characterized by an increase in the melting temperature and a considerable decrease in the temperature at which the ferroelec tric phase formed in polymer inclusions becomes unstable. It is shown that charge transfer in the composite material occurs predominantly through channels filled with the polymer.

Optical Materials, 1995

Influence of tantalum and niobium oxide on the electrical conductivity of alkali silicate glasses... more Influence of tantalum and niobium oxide on the electrical conductivity of alkali silicate glasses was investigated. The electrical measurements were performed for three types of alkali silicate glasses containing different amounts of tantalum, niobium and alkali. These glasses are promising materials for gradient elements produced by ion-exchange process.

Journal of Porous Materials, 1996

The properties of the porous glasses before and after impregnation with carbon were studied. The ... more The properties of the porous glasses before and after impregnation with carbon were studied. The electrical measurements (ac and do conductivity) were performed to investigate the structure of carbon filler in the pores. Correlation between luminescence and luminescence excitation spectra and the structure of glass was observed and investigated.

Bulletin of the Russian Academy of Sciences: Physics, 2010

The dielectric properties of composite materials prepared by embedding P(VDF60/Tr40) and P(VDF88/... more The dielectric properties of composite materials prepared by embedding P(VDF60/Tr40) and P(VDF88/Te12) polar copolymers in porous glass matrices with a mean flow-through pore diameter of around 320 nm were investigated in the temperature range 200–450 K. Strong dielectric relaxation, the characteristic time of which conformed to the Williams-Landel-Ferry law, was observed in the vicinity of glass transition point T g of an amorphous fraction of polymer inclusions. An increase (≈10 K) in the T g temperature of the amorphous fraction of incorporated polymeric materials was detected.

Journal of Applied Polymer Science, 2004

ABSTRACT

Physics and Chemistry of Glasses, 1996

Luminescent properties of porous silica glasses (PSG) that underwent the procedure of carbon redu... more Luminescent properties of porous silica glasses (PSG) that underwent the procedure of carbon reduction to enhance the intensity of light emission were studied in a wide temperature range. Photoluminescent (PL) quenching and recovery was observed in light soaking experiments. The results of quasistationary and time resolved PL measurements strongly suggest that tunnel transitions of nonequilibrium charge carriers between quantum size silicon clusters are responsible for the observed long lasting light emission.

Materials, 2020

The results of XRD, FTIR and differential scanning calorimetry (DSC) studies of empty porous sili... more The results of XRD, FTIR and differential scanning calorimetry (DSC) studies of empty porous silica matrices filled with binary mixtures of K1–xAgxNO3 (x = 0.05, 0.10) are reported in comparison with those obtained for bulk salts in the temperature range of structural phase transitions. Scanning electron microscopic data of the studied empty macroporous and microporous glasses confirmed differences in the pore morphology associated with the presence of silica gel. Accordingly, XRD and FTIR samples contain crystalline phase of KNO3 and AgNO3. The results of calorimetric investigation of porous glasses filled with binary mixtures of K1–xAgxNO3 (x = 0.05, 0.10) are presented. The results show that in the K1–xAgxNO3 nanocomposites, anomalies associated with phase transitions were detected. An influence of the mean value of pores sizes on the ferroelectric phase transition temperatures of K1–xAgxNO3 nanocrystals embedded into the porous matrices was determined. The impact of pore space s...

Materials Chemistry and Physics, 2020

Abstract Properties of dielectric and magnetic porous matrices and ferroelectrics porous glasses ... more Abstract Properties of dielectric and magnetic porous matrices and ferroelectrics porous glasses based nanocomposites were studied. Two types of modified and unmodified by iron oxides initial sodium borosilicate glasses and obtained from them porous matrices were investigated. The continuous pore structure was observed in porous glasses and additional in iron containing porous glasses inclusions of iron phase were stated. Depending on technological processes the pore diameters were estimated to be between 4 and 60 nm. The effect of structure and composition of investigated materials on electrical properties was discussed. Dynamic Impedance Spectroscopy measurements have revealed reversible. The dc conductivity and relaxation processes related to different types of transport of sodium and iron ions were discussed. The existence of ferroic KNO3 inside pores determines properties of nanocomposite based on porous matrices. The obtained porous dielectric and magnetic matrices can be applied as ferroics and multiferroeics elements.

Journal of Non-Crystalline Solids, 2020

Abstract The iron-bearing sodium borosilicate glasses with different contents of iron were prepar... more Abstract The iron-bearing sodium borosilicate glasses with different contents of iron were prepared by the charge melting method and studied by XRD, TEM, FTIR, Mossbauer and Dynamic Impedance Spectroscopy techniques. An analysis and the transmittance spectra of two-phase sodium borosilicate glasses with different contents of iron oxide were carried out. A usage of the Mossbauer spectroscopy revealed differences between two-phase and porous glasses. In both cases Fe2+ and Fe3+ ions in octahedral and tetrahedral coordination were found, while in the two-phase glasses the significant contribution of magnetite was additionally detected. The activation energy associated with the relaxation processes determined from the electric modulus spectra was found to be in a range between 0.986 eV and 0.729 eV, which is close to the activation energy for dc conductivity. Two different conduction mechanisms were observed and their physical origin was explained. The hopping between two valence states of iron and the sodium ion conduction mechanism was additionally discussed.

Crystals, 2019

The dielectric properties of composite materials prepared by the embedding of ferroelectrics pota... more The dielectric properties of composite materials prepared by the embedding of ferroelectrics potassium dihydrogen phosphate (KDP), cesium dihydrophosphate (CDP), as well as antiferroelectric ammonium dihydrogen phosphate (ADP) into porous glass matrices with an average size of through pores of 7, 46, and 320 nm have been studied. It was found that an increase occurred in the phase transitions temperature (TC) for embedded particles in comparison with corresponding bulk materials. Some possible mechanisms of influence of “restricted geometry” on the Curie temperature are discussed. Estimates of TC shifting as a result of the “pressure effect” caused by elastic stresses in embedded particles as well as the result of bias electric field influence arising due to the piezoelectric effect are made. The possibility of using the tunneling Ising model to explain the experimental results is discussed.

Bulletin of the Russian Academy of Sciences: Physics, 2019

Results are presented from studying the X-ray diffraction, heat capacities, dielectric permittivi... more Results are presented from studying the X-ray diffraction, heat capacities, dielectric permittivities, and coefficients of the volumetric thermal expansion of composite materials obtained by embedding of Rb2ZnCl4 salt into the porous matrices of borosilicate glass with average pore diameters of 46 and 320 nm in the temperature range of 120–350 K. The temperatures of transitions to the incommensurate and ferroelectric phases are determined, along with the freezing temperature of the mobility of domain boundaries in Rb2ZnCl4 particles. A substantial increase in their Curie temperature is observed.

Physics of the Solid State, 2018

Впервые выполнены исследования влияния ограниченной геометрии на теплоемкость и тепловое расширен... more Впервые выполнены исследования влияния ограниченной геометрии на теплоемкость и тепловое расширение композитов триглицинсульфат(TGS)-боросиликатное стекло. Обнаружено уменьшение энтропии и температуры фазового перехода P2 1 ↔ P21/m в компоненте TGS-при уменьшении диаметра пор стекольной матрицы, происходящее при неизменных значениях аномальных величин теплоемкости и коэффициента теплового расширения. Оценки свидетельствуют о небольшом эффекте внутреннего давления на барический коэффициент dTc /d p TGS в композитах. Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта № 16-32-00092 мол_а.