Jaroslav Cihlář - Academia.edu (original) (raw)

Papers by Jaroslav Cihlář

Ceramics, 2004

The effect of hydrothermal treatment on the phase stability, microstructure and mechanical proper... more The effect of hydrothermal treatment on the phase stability, microstructure and mechanical properties of tetragonal zirconia ceramics stabilized with 3 mol% yttria was studied. At temperatures of 140-260°C the tetragonal phase transformed into monoclinic zirconia. The degree of transformation increased with increasing temperature and time of ageing. Changes in the microstructure and mechanical properties were observed for the samples used at temperatures of 180°C and higher. The thickness of transformed layer increased with increasing temperature and at 260°C it reached a thickness of 170 µm after 10 hours. The changes in mechanical properties (hardness and fracture toughness) corresponded to the structural changes in the material caused by hydrothermal ageing. Temperatures of 180°C and higher were critical for the mechanical and structural properties of the material.

Research was curried out on the perovskite systems with general formula A1-xA‘xB1-yB‘yO3± (where ... more Research was curried out on the perovskite systems with general formula A1-xA‘xB1-yB‘yO3± (where A=La, Sm, A´=Ca, B´=Al, B=Co,Fe,Mn and Cr). Perovskite oxides were sythesized by polymerisation methods and characterised by RTG analysis, BET method, SEM and EDX. TPD spectra and catalyst testing were measured in high temperature plug flow reactor and products were analysed by mass spectrometry. It was found, that metane oxidation at ratio O2/CH40,5 depended on the temperature. Total oxidation proceeded at the temperature betwen 300-700oC to the carbon dioxide and water, while the partial oxidation of metane (POM) occured at above 700oC to the hydrogen and carbon oxid (syngas). This was ascribed by equilibrium of O2 betwen gas phase and solid perovskite. There was used 12 perovskite systems, which catalysed methane oxidation by the same way. Dry reforming of methane run above temperature 700oC. Cobaltite and ferite type perovskites were found as the most active catalytic systems. On the...

Journal of the American Ceramic Society, 2016

International Journal of Hydrogen Energy, 2021

Abstract Heterophase TiO2 nanoparticles formed in the presence of a very low concentration of a s... more Abstract Heterophase TiO2 nanoparticles formed in the presence of a very low concentration of a substance with two donor groups were studied and the mechanism of their formation was proposed. The TiO2 nanoparticles were prepared by low-temperature hydrolysis and polycondensation of Ti (IV) n-propoxide in the presence of lactic acid (LA). The phase composition of the nanoparticles was controlled by the LA/Ti molar ratio ranging from 0.02 to 3.0. At low LA/Ti molar ratios, biphasic anatase-brookite was formed, at average LA/Ti molar ratios, anatase-brookite-rutile particles were formed, and at high molar ratios, pure anatase was formed. By using the low LA/Ti molar ratios, the low-temperature colloidal synthesis made it possible to control the composition of heterophase mesoporous TiO2 nanoparticles with a high specific surface area and high photocatalytic activity in the production of hydrogen by water splitting. The highest photocatalytic activity was exhibited by anatase-brookite nanoparticles containing 46–65% brookite, synthesized at LA/Ti molar ratios in the range of 0. 033 to 0.1.

IOP Conference Series: Materials Science and Engineering, 2021

Mo-La2O3 composites are potential high-temperature materials for future technology devices operat... more Mo-La2O3 composites are potential high-temperature materials for future technology devices operating at temperatures above 1300 °C because of their excellent thermal stability, high mechanical properties and good creep resistance. In this study, we focused on the preparation of Mo-matrix/lanthanum oxide (La2O3) composite powders using high-energy attrition milling. The effects of rotational milling speed (350 and 800 rpm) and La2O3 content (2.5 and 10 vol. %) on the microstructural evolution, phase composition, morphology, and distribution of the second phase in the produced composite Mo-La2O3 powders were investigated in details. The results show that the most interesting composite powder was Mo-10 vol.% La2O3 produced using a rotational speed of 800 rpm, which exhibited better distribution, smaller particle size and higher amount of ceramic phase introduced in the interiors of the Mo grains.

Inorganic Materials, 2016

Ceramics International, 2017

As compared to a bulk material, the fibres exhibit novel physical and chemical properties arising... more As compared to a bulk material, the fibres exhibit novel physical and chemical properties arising from their unique geometric features such as high surface area, surface to volume ratio and small fibre diameter. This paper is focused on the fabrication of nanosized 8 mol% yttria doped zirconia fibres by electrospinning from propoxide/polyvinylpyrrolidonebased precursors and physical-chemical characterization of the ceramic fibres with an energy application potential. Fully crystalline composition of cubic zirconia was detected after fibre heat treatment at 700°C. The fibre morphology was changed with increasing temperature from flexible nonsintered nanoparticle system at 700°C through porous nanograin structure at 900°C and nonporous structure with coarser nanograins at 1100°C to fragile chain-like fibre structure formed of elongated submicrometer grains at 1300-1450°C. The densification and grain growth kinetics were described in two stages in the temperature range from 700°C up to 1450°C.

Journal of the American Ceramic Society, 2006

Journal of the American Ceramic Society, 2016

Synthesis of CeO2, Pr2O3, and Sm2O3 nanorods and their sintering have been investigated. In a str... more Synthesis of CeO2, Pr2O3, and Sm2O3 nanorods and their sintering have been investigated. In a strongly alkaline medium, nanorods of CeO2, Pr2O3, and Sm2O3 were prepared from trivalent salts of rare earths (Ce, Pr, Sm) via precipitation synthesis. Nanorods were formed by nanocrystallites of fibrous structure, which were produced by the mechanism of self-arrangement of hexagonal particles of Re(III) hydroxides. The subsequent transformation of hydroxide into oxide proceeded via self-preservation of the rod-like structure. In CeO2, the fibrous structure was noncohesive during thermal treatment at temperature of 500°C and higher. Regardless of the shape of the CeO2 particles (spherical versus rod-like), sintered ceramic was formed by equiaxial grains. The cohesion of the fibrous structure of Pr and Sm oxides was higher than in CeO2. The rod-like shape of the particles of Pr and Sm oxides was (partially) preserved during sintering.

Journal of the American Ceramic Society, 2015

The preparation of Ba0.85Ca0.15 Zr0.1Ti0.9O3 (BCZT) powders by wet chemical methods has been inve... more The preparation of Ba0.85Ca0.15 Zr0.1Ti0.9O3 (BCZT) powders by wet chemical methods has been investigated, and the powders used to explore relationships between the microstructure and piezoelectric properties (d33 coefficient) of sintered BCZT ceramics. Sol–gel synthesis has been shown to be a successful method for the preparation of BCZT nanopowders with a pure tetragonal perovskite phase structure, specific surface area up to 21.8 m2/g and a mean particle size of 48 nm. These powders were suitable for the fabrication of dense BCZT ceramics with fine-grain microstructures. The ceramics with the highest density of 95% theoretical density (TD) and grain size of 1.3 μm were prepared by uniaxial pressing followed by a two-step sintering approach which contributed to the refinement of the BCTZ microstructure. A decrease in the grain size to 0.8–0.9 μm was achieved when samples were prepared using cold isostatic pressing. Using various sintering schedules, BCZT ceramics with broad range of grain sizes (0.8–60.5 μm) were prepared. The highest d33 = 410.8 ± 13.2 pC/N was exhibited by ceramics prepared from sol–gel powder sintered at 1425°C, with the relative density of 89.6%TD and grain size of 36 μm.

Ceramics International, 2015

Abstract The stabilisation of hydroxyapatite (HA) particles in dispersions containing 2-propanol ... more Abstract The stabilisation of hydroxyapatite (HA) particles in dispersions containing 2-propanol and monochloroacetic acid (MCAA) was studied. The surface of HA (Ca 2+ cations) was stabilized by chemical adsorption of non-dissociated MCAA molecules via polar Cl atoms followed by dissociation (cleavage of the protons), which led to negative charging of the HA particles. Colloidal dispersions were milled for 0, 2 and 24 h in a planetary ball mill before electrophoretic deposition (EPD). The electrical conductivity of dispersions was modified by adding an indifferent electrolyte (LiCl) to obtain crack-free deposits with a smooth surface. HA and HA/t-ZrO 2 composites containing 2, 4, 8 and 16 wt% zirconia microfibres were prepared by EPD. HA decomposed into α-TCP, β-TCP and partially substituted calcium phosphate by the action of Li + cations during sintering. Elastic modulus and Vickers hardness of composites increased with milling time of the dispersions prior to EPD and decreased with the quantity of zirconia microfibres in the deposits, depending on the composite density. Fracture toughness of the composites was twice as high as that of pure HA due to the presence of orientated zirconia microfibres, finer microstructure, tougher β-TCP phase and pores. The two-week soaking in simulated body fluid revealed the bioactivity of all prepared materials.

Ceramics - Processing, Reliability, Tribology and Wear, 2006

Prague medical report, 2007

The important condition for the adhesive bond between dentine and composite filling is the change... more The important condition for the adhesive bond between dentine and composite filling is the change of dentine property from hydrophilic to hydrophobic. Substances able to accomplish this change, dentinal adhesives, have undergone complex development. Recently, the so-called self-etching adhesives have been formulated. The aim of the present paper was to compare the structural pattern of dentin/resin interface after the application of dentinal adhesives used in total- and self-etching technique. Dentinal adhesives Single bond, Prime bond, Prompt-L-pop Adper, and Xeno III were used. The former two belong to the total etch technique, the latter two to the self-etching technique. The dentin/resin interface was studied in transmission (TEM) and scanning (SEM) electron microscope. In TEM sixteen teeth were investigated, each adhesive was applied in four teeth. Under SEM forty teeth were studied, each adhesive was applied in ten teeth. The obtained results demonstrated that all the dentine ...

The kinetics of sintering of ceramic materials based on alumina, zirconia and of their composites... more The kinetics of sintering of ceramic materials based on alumina, zirconia and of their composites was studied by means of the high-temperature dilatometer. It was found that the alumina-based ceramics sintered at higher temperatures than those based on zirconia, that at a heating rate of 10°C min -1 the resultant theoretical densities were comparable to those obtained at rates of 5 or 2°C min -1 , and that the resultant relative densities were higher with materials prepared by cold isostatic pressing than with those prepared by injection moulding. With the alumina and zirconia-based materials, the values of linear thermal expansion coefficients were identical with those specified in the literature.

International Journal of Modern Physics B, 2010

Indium vanadates for severe applications as photocatalysts, anodes for Li rechargeable batteries ... more Indium vanadates for severe applications as photocatalysts, anodes for Li rechargeable batteries or electrochromic devices were prepared via conventional and non-conventional preparation methods. The conventional high temperature solid state reaction was performed at 800°C for 25 hours and the non-conventional microwave-assisted synthesis was performed at 220°C for different reaction times under hydrothermal conditions. The as-prepared powders were characterized in terms of phase composition by X-Ray diffraction analysis (XRD) and infrared spectroscopy (IR) and of powder morphology by scanning electron microscopy (SEM) and BET method. Nanosized indium vanadate powders were successfully synthesized by non-conventional microwave-assisted hydrothermal method. The dense ceramic bodies suitable for electrical conductivity measurements with 96% t.d. were obtained by sintering of powders prepared by high-temperature solid state reaction at 1100°C for 4 h with admission of oleic acid as a b...

Journal of the European Ceramic Society, 2014

Please cite this article in press as: Drdlik D, et al. Influence of anionic stabilization of alum... more Please cite this article in press as: Drdlik D, et al. Influence of anionic stabilization of alumina particles in 2-propanol medium on the electrophoretic deposition and mechanical properties of deposits.

Ceramics, 2004

The effect of hydrothermal treatment on the phase stability, microstructure and mechanical proper... more The effect of hydrothermal treatment on the phase stability, microstructure and mechanical properties of tetragonal zirconia ceramics stabilized with 3 mol% yttria was studied. At temperatures of 140-260°C the tetragonal phase transformed into monoclinic zirconia. The degree of transformation increased with increasing temperature and time of ageing. Changes in the microstructure and mechanical properties were observed for the samples used at temperatures of 180°C and higher. The thickness of transformed layer increased with increasing temperature and at 260°C it reached a thickness of 170 µm after 10 hours. The changes in mechanical properties (hardness and fracture toughness) corresponded to the structural changes in the material caused by hydrothermal ageing. Temperatures of 180°C and higher were critical for the mechanical and structural properties of the material.

Research was curried out on the perovskite systems with general formula A1-xA‘xB1-yB‘yO3± (where ... more Research was curried out on the perovskite systems with general formula A1-xA‘xB1-yB‘yO3± (where A=La, Sm, A´=Ca, B´=Al, B=Co,Fe,Mn and Cr). Perovskite oxides were sythesized by polymerisation methods and characterised by RTG analysis, BET method, SEM and EDX. TPD spectra and catalyst testing were measured in high temperature plug flow reactor and products were analysed by mass spectrometry. It was found, that metane oxidation at ratio O2/CH40,5 depended on the temperature. Total oxidation proceeded at the temperature betwen 300-700oC to the carbon dioxide and water, while the partial oxidation of metane (POM) occured at above 700oC to the hydrogen and carbon oxid (syngas). This was ascribed by equilibrium of O2 betwen gas phase and solid perovskite. There was used 12 perovskite systems, which catalysed methane oxidation by the same way. Dry reforming of methane run above temperature 700oC. Cobaltite and ferite type perovskites were found as the most active catalytic systems. On the...

Journal of the American Ceramic Society, 2016

International Journal of Hydrogen Energy, 2021

Abstract Heterophase TiO2 nanoparticles formed in the presence of a very low concentration of a s... more Abstract Heterophase TiO2 nanoparticles formed in the presence of a very low concentration of a substance with two donor groups were studied and the mechanism of their formation was proposed. The TiO2 nanoparticles were prepared by low-temperature hydrolysis and polycondensation of Ti (IV) n-propoxide in the presence of lactic acid (LA). The phase composition of the nanoparticles was controlled by the LA/Ti molar ratio ranging from 0.02 to 3.0. At low LA/Ti molar ratios, biphasic anatase-brookite was formed, at average LA/Ti molar ratios, anatase-brookite-rutile particles were formed, and at high molar ratios, pure anatase was formed. By using the low LA/Ti molar ratios, the low-temperature colloidal synthesis made it possible to control the composition of heterophase mesoporous TiO2 nanoparticles with a high specific surface area and high photocatalytic activity in the production of hydrogen by water splitting. The highest photocatalytic activity was exhibited by anatase-brookite nanoparticles containing 46–65% brookite, synthesized at LA/Ti molar ratios in the range of 0. 033 to 0.1.

IOP Conference Series: Materials Science and Engineering, 2021

Mo-La2O3 composites are potential high-temperature materials for future technology devices operat... more Mo-La2O3 composites are potential high-temperature materials for future technology devices operating at temperatures above 1300 °C because of their excellent thermal stability, high mechanical properties and good creep resistance. In this study, we focused on the preparation of Mo-matrix/lanthanum oxide (La2O3) composite powders using high-energy attrition milling. The effects of rotational milling speed (350 and 800 rpm) and La2O3 content (2.5 and 10 vol. %) on the microstructural evolution, phase composition, morphology, and distribution of the second phase in the produced composite Mo-La2O3 powders were investigated in details. The results show that the most interesting composite powder was Mo-10 vol.% La2O3 produced using a rotational speed of 800 rpm, which exhibited better distribution, smaller particle size and higher amount of ceramic phase introduced in the interiors of the Mo grains.

Inorganic Materials, 2016

Ceramics International, 2017

As compared to a bulk material, the fibres exhibit novel physical and chemical properties arising... more As compared to a bulk material, the fibres exhibit novel physical and chemical properties arising from their unique geometric features such as high surface area, surface to volume ratio and small fibre diameter. This paper is focused on the fabrication of nanosized 8 mol% yttria doped zirconia fibres by electrospinning from propoxide/polyvinylpyrrolidonebased precursors and physical-chemical characterization of the ceramic fibres with an energy application potential. Fully crystalline composition of cubic zirconia was detected after fibre heat treatment at 700°C. The fibre morphology was changed with increasing temperature from flexible nonsintered nanoparticle system at 700°C through porous nanograin structure at 900°C and nonporous structure with coarser nanograins at 1100°C to fragile chain-like fibre structure formed of elongated submicrometer grains at 1300-1450°C. The densification and grain growth kinetics were described in two stages in the temperature range from 700°C up to 1450°C.

Journal of the American Ceramic Society, 2006

Journal of the American Ceramic Society, 2016

Synthesis of CeO2, Pr2O3, and Sm2O3 nanorods and their sintering have been investigated. In a str... more Synthesis of CeO2, Pr2O3, and Sm2O3 nanorods and their sintering have been investigated. In a strongly alkaline medium, nanorods of CeO2, Pr2O3, and Sm2O3 were prepared from trivalent salts of rare earths (Ce, Pr, Sm) via precipitation synthesis. Nanorods were formed by nanocrystallites of fibrous structure, which were produced by the mechanism of self-arrangement of hexagonal particles of Re(III) hydroxides. The subsequent transformation of hydroxide into oxide proceeded via self-preservation of the rod-like structure. In CeO2, the fibrous structure was noncohesive during thermal treatment at temperature of 500°C and higher. Regardless of the shape of the CeO2 particles (spherical versus rod-like), sintered ceramic was formed by equiaxial grains. The cohesion of the fibrous structure of Pr and Sm oxides was higher than in CeO2. The rod-like shape of the particles of Pr and Sm oxides was (partially) preserved during sintering.

Journal of the American Ceramic Society, 2015

The preparation of Ba0.85Ca0.15 Zr0.1Ti0.9O3 (BCZT) powders by wet chemical methods has been inve... more The preparation of Ba0.85Ca0.15 Zr0.1Ti0.9O3 (BCZT) powders by wet chemical methods has been investigated, and the powders used to explore relationships between the microstructure and piezoelectric properties (d33 coefficient) of sintered BCZT ceramics. Sol–gel synthesis has been shown to be a successful method for the preparation of BCZT nanopowders with a pure tetragonal perovskite phase structure, specific surface area up to 21.8 m2/g and a mean particle size of 48 nm. These powders were suitable for the fabrication of dense BCZT ceramics with fine-grain microstructures. The ceramics with the highest density of 95% theoretical density (TD) and grain size of 1.3 μm were prepared by uniaxial pressing followed by a two-step sintering approach which contributed to the refinement of the BCTZ microstructure. A decrease in the grain size to 0.8–0.9 μm was achieved when samples were prepared using cold isostatic pressing. Using various sintering schedules, BCZT ceramics with broad range of grain sizes (0.8–60.5 μm) were prepared. The highest d33 = 410.8 ± 13.2 pC/N was exhibited by ceramics prepared from sol–gel powder sintered at 1425°C, with the relative density of 89.6%TD and grain size of 36 μm.

Ceramics International, 2015

Abstract The stabilisation of hydroxyapatite (HA) particles in dispersions containing 2-propanol ... more Abstract The stabilisation of hydroxyapatite (HA) particles in dispersions containing 2-propanol and monochloroacetic acid (MCAA) was studied. The surface of HA (Ca 2+ cations) was stabilized by chemical adsorption of non-dissociated MCAA molecules via polar Cl atoms followed by dissociation (cleavage of the protons), which led to negative charging of the HA particles. Colloidal dispersions were milled for 0, 2 and 24 h in a planetary ball mill before electrophoretic deposition (EPD). The electrical conductivity of dispersions was modified by adding an indifferent electrolyte (LiCl) to obtain crack-free deposits with a smooth surface. HA and HA/t-ZrO 2 composites containing 2, 4, 8 and 16 wt% zirconia microfibres were prepared by EPD. HA decomposed into α-TCP, β-TCP and partially substituted calcium phosphate by the action of Li + cations during sintering. Elastic modulus and Vickers hardness of composites increased with milling time of the dispersions prior to EPD and decreased with the quantity of zirconia microfibres in the deposits, depending on the composite density. Fracture toughness of the composites was twice as high as that of pure HA due to the presence of orientated zirconia microfibres, finer microstructure, tougher β-TCP phase and pores. The two-week soaking in simulated body fluid revealed the bioactivity of all prepared materials.

Ceramics - Processing, Reliability, Tribology and Wear, 2006

Prague medical report, 2007

The important condition for the adhesive bond between dentine and composite filling is the change... more The important condition for the adhesive bond between dentine and composite filling is the change of dentine property from hydrophilic to hydrophobic. Substances able to accomplish this change, dentinal adhesives, have undergone complex development. Recently, the so-called self-etching adhesives have been formulated. The aim of the present paper was to compare the structural pattern of dentin/resin interface after the application of dentinal adhesives used in total- and self-etching technique. Dentinal adhesives Single bond, Prime bond, Prompt-L-pop Adper, and Xeno III were used. The former two belong to the total etch technique, the latter two to the self-etching technique. The dentin/resin interface was studied in transmission (TEM) and scanning (SEM) electron microscope. In TEM sixteen teeth were investigated, each adhesive was applied in four teeth. Under SEM forty teeth were studied, each adhesive was applied in ten teeth. The obtained results demonstrated that all the dentine ...

The kinetics of sintering of ceramic materials based on alumina, zirconia and of their composites... more The kinetics of sintering of ceramic materials based on alumina, zirconia and of their composites was studied by means of the high-temperature dilatometer. It was found that the alumina-based ceramics sintered at higher temperatures than those based on zirconia, that at a heating rate of 10°C min -1 the resultant theoretical densities were comparable to those obtained at rates of 5 or 2°C min -1 , and that the resultant relative densities were higher with materials prepared by cold isostatic pressing than with those prepared by injection moulding. With the alumina and zirconia-based materials, the values of linear thermal expansion coefficients were identical with those specified in the literature.

International Journal of Modern Physics B, 2010

Indium vanadates for severe applications as photocatalysts, anodes for Li rechargeable batteries ... more Indium vanadates for severe applications as photocatalysts, anodes for Li rechargeable batteries or electrochromic devices were prepared via conventional and non-conventional preparation methods. The conventional high temperature solid state reaction was performed at 800°C for 25 hours and the non-conventional microwave-assisted synthesis was performed at 220°C for different reaction times under hydrothermal conditions. The as-prepared powders were characterized in terms of phase composition by X-Ray diffraction analysis (XRD) and infrared spectroscopy (IR) and of powder morphology by scanning electron microscopy (SEM) and BET method. Nanosized indium vanadate powders were successfully synthesized by non-conventional microwave-assisted hydrothermal method. The dense ceramic bodies suitable for electrical conductivity measurements with 96% t.d. were obtained by sintering of powders prepared by high-temperature solid state reaction at 1100°C for 4 h with admission of oleic acid as a b...

Journal of the European Ceramic Society, 2014

Please cite this article in press as: Drdlik D, et al. Influence of anionic stabilization of alum... more Please cite this article in press as: Drdlik D, et al. Influence of anionic stabilization of alumina particles in 2-propanol medium on the electrophoretic deposition and mechanical properties of deposits.