Karla Barcova | VSB - Technical University of Ostrava (original) (raw)

Papers by Karla Barcova

Bulletin of Electrical Engineering and Informatics

The main aim of this article is to design a monitoring center for collecting and evaluating the p... more The main aim of this article is to design a monitoring center for collecting and evaluating the physiological function of retired patients in nursing homes. The system should be able to collect the information of body heat, heart rate, blood oxygen, orientation, and sleep time in the form of the little bracelet. The evaluating part of the system with the program can be placed into personal computer (PC) which can provide a user-friendly interface and easy managing. The program can display all needed information of the patient from previous days or months in the form of the graphs and the nursing person can have the view of the patient´s physiological health. The evaluation and the collection of the data from each patient are done only on the card and the computer is only a device for live-view and managing. In case of the power failure, the monitoring system will be still operating normally due to the uninterruptible power supply (UPS) in the form of the battery. It means that the s...

Defence Science Journal

On the basis of an analysis of terrorist attacks carried out worldwide, where in recent years a p... more On the basis of an analysis of terrorist attacks carried out worldwide, where in recent years a preference for the use of bulk explosives placed in vehicles prevails, effective protection against these malicious explosive-containing systems that have a single goal-to cause death and significant material damage in a large radius is dealt. These improvised explosive devices are, in pyrotechnical terms, ranked as one of the most effective weapons, with a highly destructive character of explosive effect. A special water shaped charge that is able to destructively disassemble a bomb without initiation has been developed as an effective invasive means of eliminating similarly designed terrorist explosives hidden in cars, a condition which allows for considerable variation in location.

AIP Conference Proceedings

Vitreous enameling on steel is carried out to provide a protective layer against chemical corrosi... more Vitreous enameling on steel is carried out to provide a protective layer against chemical corrosion from the surrounding environment. The glass bonds with the steel to form a composite material. The Mössbauer spectroscopy was firstly applied to study the vitreous enameling in which the complex of processes, as diffusion of species, adhesion between the glass and the steel, galvanic reactions, plays an important role. The Mössbauer spectroscopy provides unique information about the Fe-phase structure of the vitreous enamel layer and that of the steel-enamel interface. Diffusion of iron from steel surface towards enamel layer and formation of a new Fe 2+ phase was proved.

International Journal of Critical Infrastructure Protection, 2016

Diffusion and Defect Data Solid State Data Part B Solid State Phenomena, 2009

... Ostrava, 17. listopadu 15, 708 33 Ostrava Poruba, Czech Republic akamila.hrabovska@ vsb.cz, b... more ... Ostrava, 17. listopadu 15, 708 33 Ostrava Poruba, Czech Republic akamila.hrabovska@ vsb.cz, bjitka.podjuklova@vsb.cz, ckarla.barcova@vsb.cz, dlenka.dobrovodska.st@ vsb.cz, ekaterina.pelikanova.st@vsb.cz Abstract. Vitreous ...

Material Research in Atomic Scale by Mössbauer Spectroscopy, 2003

ABSTRACT The oxidation mechanisms of Fe2+ in different iron-bearing minerals depend strongly on t... more ABSTRACT The oxidation mechanisms of Fe2+ in different iron-bearing minerals depend strongly on the external conditions, including the heating temperature, mineral crystal unity, pressure conditions and oxidation atmosphere. However, slight differences in the internal features (the total content of iron, distribution of iron in non-equivalent sites, chemical environment and coordination of iron) can also significantly influence the oxidation mechanism. Thus, different oxidation routes can occur depending on the structural ordering and external conditions.

Industrial Applications of the Mössbauer Effect, 2002

A high-energy water jet combined with silicate garnets as abrasives has been proven to be a power... more A high-energy water jet combined with silicate garnets as abrasives has been proven to be a powerful tool for disintegration of hard materials. Thermal heating of the garnets is one way for structure improvement of the abrasive material. Room-temperature Mössbauer spectra of initial powdered almandine samples are characterised by one doublet corresponding to Fe 2+ in dodecahedral position 24c. Almandine garnet, industrial product Barton HP 80 as reference material in all experiments, has a second doublet corresponding to Fe 3+ in octahedral position 16a. In roomtemperature spectra of heated almandine garnet samples from locality Ktíš and Měděnec (heated under temperatures 200-1000 • C by 100 degrees for 1 hour in air) a new doublet originating from γ-Fe 2 O 3 nanoparticles appeared. Under a heating temperature of higher than 800 • C, the broad sextets of α-Fe 2 O 3 and ε-Fe 2 O 3 in spectra were discovered. No additional doublets or sextets appeared in room-temperature Mössbauer spectra of reference material of almandine garnet Barton HP 80 heated under each temperature.

Industrial Applications of the Mössbauer Effect, 2002

The thermally induced solid-state syntheses of γ-Fe 2 O 3 nanoparticles from iron-bearing materia... more The thermally induced solid-state syntheses of γ-Fe 2 O 3 nanoparticles from iron-bearing materials (FeSO 4 , Fe 2 (C 2 O 4) 3 and almandine garnet) are described. Magnetic properties, particles size and the mechanism of the structural change of γ-Fe 2 O 3 nanoparticles have been investigated using 57 Fe Mössbauer spectroscopy, X-ray powder diffraction (XRD) and atomic force microscopy (AFM). γ-Fe 2 O 3 nanoparticles are transformed into hematite via ε-Fe 2 O 3 as the intermediate.

The transformation mechanism of Fe cations in natural olivine after thermal treatments in air has... more The transformation mechanism of Fe cations in natural olivine after thermal treatments in air has been studied using mainly 57 Fe Mössbauer spectroscopy. J-Fe 2 O 3 nanoparticles appear as the primary Fe 3+ phase in Mössbauer spectra of olivine samples heated at 600-900 °C. These nanoparticles are thermally unstable and they are transformed to D-Fe 2 O 3 with the increase of heating time. Another transformation mechanism of iron related with the complete decomposition of olivine structure has been observed at temperatures of 1000 °C and higher. The mixed oxide MgFe 2 O 4 with the spinel structure and enstatite MgSiO 3 were identified as iron-bearing decomposition products.

Czechoslovak Journal of Physics - CZECH J PHYS, 2001

The thermal decomposition of almandine garnet from Zoltye Vody, Ukraine, has been studied using57... more The thermal decomposition of almandine garnet from Zoltye Vody, Ukraine, has been studied using57Fe M�ssbauer spectroscopy. Room temperature M�ssbauer spectrum of the initial powdered sample is characterised by one doublet corresponding to Fe2+ in dodecahedral position 24c. In the room temperature spectra of all heated almandine samples, a doublet corresponding to γ-Fe2O3 nanoparticles appeared. Depending on experimental conditions (heating temperature and time), the additional spectral lines of α-Fe2O3 and ε-Fe2O3 were observed in M�ssbauer spectra. It is obvious that the thermal transformation of almandine garnet in air is related to the primary formation of γ-Fe2O3 superparamagnetic nanoparticles. γ-Fe2O3 nanoparticles are transformed into ε-Fe2O3 and consequently into α-Fe2O3 at higher temperatures. The mechanism and kinetics of the individual structural transformations depend on experimental conditions — mainly on the heating temperature and size of the particles.

Surface and Interface Analysis, 2006

ABSTRACT An effect of the enamel ageing on the mechanical properties and composition of the steel... more ABSTRACT An effect of the enamel ageing on the mechanical properties and composition of the steel-enamel system was monitored by means of conversion electron and transmission Mössbauer spectroscopy, electron-microprobe analysis, thermogravimetry and microhardness measurement. Two enamels differing in the time delay between their preparation and application on the steel surface (1 day vs 30 days) were used for this comparative study. After the enamelling procedure, the qualitative phase composition of both samples is similar, including α-Fe, FeO, Fe3O4, α-Fe2O3, Fe2SiO4 and the FeNi particles. Despite this similar qualitative phase composition of differently aged enamels, the mechanical properties of the samples are significantly different. Copyright © 2006 John Wiley & Sons, Ltd.

Surface and Coatings Technology, 2006

Mössbauer spectroscopy in transmission geometry, performed simultaneously with conversion X-ray, ... more Mössbauer spectroscopy in transmission geometry, performed simultaneously with conversion X-ray, and conversion electron Mössbauer spectroscopy, X-ray powder diffraction and electron microprobe analysis (EMPA), have been used to monitor the effects of a chemical pre-treatment on the phase composition of a “steel–enamel interface” of a hot-rolled steel surface formed during a thermally induced coating process. In this comparative study, we have

Physics and Chemistry of Minerals, 2003

The mechanism of thermally induced oxidation of Fe 2+ from natural pyrope has been studied at 100... more The mechanism of thermally induced oxidation of Fe 2+ from natural pyrope has been studied at 1000 and 1100°C using 57 Fe Mo¨ssbauer spectroscopy in conjunction with XRD, XRF, AFM, QELS, TG, DTA and electron microprobe analyses. At 1000°C, the nondestructive oxidation of Fe 2+ in air includes the partial stabilization of Fe 3+ in the dodecahedral 24c position of the garnet structure and the simultaneous formation of hematite particles (15-20 nm). The incorporation of the magnesium ions to the hematite structure results in the suppression of the Morin transition temperature to below 20 K. The general garnet structure is preserved during the redox process at 1000°C, in accordance with XRD and DTA data. At 1100°C, however, oxidative conversion of pyrope to the mixed magnesium aluminium iron oxide, Fe-orthoenstatite and cristoballite was observed. During this destructive decomposition, Fe 2+ is predominantly oxidized and incorporated into the spinel structure of Mg(Al,Fe) 2 O 4 and partially stabilized in the structure of orthoenstatite, (Mg,Fe)SiO 3. The combination of XRD and Mo¨ssbauer data suggest the definite reaction mechanism prevailing, including the refinement of the chemical composition and quantification of the reaction products. The reaction mechanism indicates that the respective distribution of Fe 2+ and Fe 3+ to the enstatite and spinel structures is determined by the total content of Fe 2+ in pyrope. Keywords Fe-bearing garnet AE Mo¨ssbauer spectroscopy AE Oxidation mechanism AE Decomposition products AE Alpha Fe 2 O 3

Hyperfine Interactions, 2000

The natural garnets from almandine (Fe 3 Al 2 Si 3 O 12)-pyrope (Mg 3 Al 2 Si 3 O 12) series with... more The natural garnets from almandine (Fe 3 Al 2 Si 3 O 12)-pyrope (Mg 3 Al 2 Si 3 O 12) series with the iron to magnesium atomic ratio ranging from 0.2 to 1 were characterised and their thermal behaviour at 1200 • C studied by 57 Fe Mössbauer spectroscopy, X-ray powder diffraction, X-ray fluorescence, DTA, TG and electron microprobe analysis. The pyrope-type samples with a dominant magnesium content at position 24c in the cubic garnet structure undergo oxidative decomposition at 1200 • C resulting in the formation of the paramagnetic spinel Mg(Al,Fe) 2 O 4 structure with a low iron content, enstatite (Mg,Fe)SiO 3 and anorthite CaAl 2 Si 2 O 8 as the host compound for calcium. Contrary to pyropes, the iron-rich garnets exhibit complete oxidation at 1200 • C conforming to the formation of magnetically ordered nanocrystalline γ-Fe 2 O 3 or Mg(Fe,Al) 2 O 4 spinels depending on the initial chemical composition of the garnets. In the reaction products of iron-rich garnets, cordierite (Mg 2 Al 4 Si 5 O 18) and anorthite were identified as non-ferrous phases.

Czechoslovak Journal of Physics, 2006

® 2.1 Preparation of the samples ® 2.2 Sample characterisation 3.Results and discussion 4.Conclus... more ® 2.1 Preparation of the samples ® 2.2 Sample characterisation 3.Results and discussion 4.Conclusion 11.-15.6.2006

ABSTRACT An effect of the enamel ageing on the mechanical properties and composition of the steel... more ABSTRACT An effect of the enamel ageing on the mechanical properties and composition of the steel-enamel system was monitored by means of conversion electron and transmission Mössbauer spectroscopy, electron-microprobe analysis, thermogravimetry and microhardness measurement. Two enamels differing in the time delay between their preparation and application on the steel surface (1 day vs 30 days) were used for this comparative study. After the enamelling procedure, the qualitative phase composition of both samples is similar, including α-Fe, FeO, Fe3O4, α-Fe2O3, Fe2SiO4 and the FeNi particles. Despite this similar qualitative phase composition of differently aged enamels, the mechanical properties of the samples are significantly different. Copyright © 2006 John Wiley & Sons, Ltd.

Bulletin of Electrical Engineering and Informatics

The main aim of this article is to design a monitoring center for collecting and evaluating the p... more The main aim of this article is to design a monitoring center for collecting and evaluating the physiological function of retired patients in nursing homes. The system should be able to collect the information of body heat, heart rate, blood oxygen, orientation, and sleep time in the form of the little bracelet. The evaluating part of the system with the program can be placed into personal computer (PC) which can provide a user-friendly interface and easy managing. The program can display all needed information of the patient from previous days or months in the form of the graphs and the nursing person can have the view of the patient´s physiological health. The evaluation and the collection of the data from each patient are done only on the card and the computer is only a device for live-view and managing. In case of the power failure, the monitoring system will be still operating normally due to the uninterruptible power supply (UPS) in the form of the battery. It means that the s...

Defence Science Journal

On the basis of an analysis of terrorist attacks carried out worldwide, where in recent years a p... more On the basis of an analysis of terrorist attacks carried out worldwide, where in recent years a preference for the use of bulk explosives placed in vehicles prevails, effective protection against these malicious explosive-containing systems that have a single goal-to cause death and significant material damage in a large radius is dealt. These improvised explosive devices are, in pyrotechnical terms, ranked as one of the most effective weapons, with a highly destructive character of explosive effect. A special water shaped charge that is able to destructively disassemble a bomb without initiation has been developed as an effective invasive means of eliminating similarly designed terrorist explosives hidden in cars, a condition which allows for considerable variation in location.

AIP Conference Proceedings

Vitreous enameling on steel is carried out to provide a protective layer against chemical corrosi... more Vitreous enameling on steel is carried out to provide a protective layer against chemical corrosion from the surrounding environment. The glass bonds with the steel to form a composite material. The Mössbauer spectroscopy was firstly applied to study the vitreous enameling in which the complex of processes, as diffusion of species, adhesion between the glass and the steel, galvanic reactions, plays an important role. The Mössbauer spectroscopy provides unique information about the Fe-phase structure of the vitreous enamel layer and that of the steel-enamel interface. Diffusion of iron from steel surface towards enamel layer and formation of a new Fe 2+ phase was proved.

International Journal of Critical Infrastructure Protection, 2016

Diffusion and Defect Data Solid State Data Part B Solid State Phenomena, 2009

... Ostrava, 17. listopadu 15, 708 33 Ostrava Poruba, Czech Republic akamila.hrabovska@ vsb.cz, b... more ... Ostrava, 17. listopadu 15, 708 33 Ostrava Poruba, Czech Republic akamila.hrabovska@ vsb.cz, bjitka.podjuklova@vsb.cz, ckarla.barcova@vsb.cz, dlenka.dobrovodska.st@ vsb.cz, ekaterina.pelikanova.st@vsb.cz Abstract. Vitreous ...

Material Research in Atomic Scale by Mössbauer Spectroscopy, 2003

ABSTRACT The oxidation mechanisms of Fe2+ in different iron-bearing minerals depend strongly on t... more ABSTRACT The oxidation mechanisms of Fe2+ in different iron-bearing minerals depend strongly on the external conditions, including the heating temperature, mineral crystal unity, pressure conditions and oxidation atmosphere. However, slight differences in the internal features (the total content of iron, distribution of iron in non-equivalent sites, chemical environment and coordination of iron) can also significantly influence the oxidation mechanism. Thus, different oxidation routes can occur depending on the structural ordering and external conditions.

Industrial Applications of the Mössbauer Effect, 2002

A high-energy water jet combined with silicate garnets as abrasives has been proven to be a power... more A high-energy water jet combined with silicate garnets as abrasives has been proven to be a powerful tool for disintegration of hard materials. Thermal heating of the garnets is one way for structure improvement of the abrasive material. Room-temperature Mössbauer spectra of initial powdered almandine samples are characterised by one doublet corresponding to Fe 2+ in dodecahedral position 24c. Almandine garnet, industrial product Barton HP 80 as reference material in all experiments, has a second doublet corresponding to Fe 3+ in octahedral position 16a. In roomtemperature spectra of heated almandine garnet samples from locality Ktíš and Měděnec (heated under temperatures 200-1000 • C by 100 degrees for 1 hour in air) a new doublet originating from γ-Fe 2 O 3 nanoparticles appeared. Under a heating temperature of higher than 800 • C, the broad sextets of α-Fe 2 O 3 and ε-Fe 2 O 3 in spectra were discovered. No additional doublets or sextets appeared in room-temperature Mössbauer spectra of reference material of almandine garnet Barton HP 80 heated under each temperature.

Industrial Applications of the Mössbauer Effect, 2002

The thermally induced solid-state syntheses of γ-Fe 2 O 3 nanoparticles from iron-bearing materia... more The thermally induced solid-state syntheses of γ-Fe 2 O 3 nanoparticles from iron-bearing materials (FeSO 4 , Fe 2 (C 2 O 4) 3 and almandine garnet) are described. Magnetic properties, particles size and the mechanism of the structural change of γ-Fe 2 O 3 nanoparticles have been investigated using 57 Fe Mössbauer spectroscopy, X-ray powder diffraction (XRD) and atomic force microscopy (AFM). γ-Fe 2 O 3 nanoparticles are transformed into hematite via ε-Fe 2 O 3 as the intermediate.

The transformation mechanism of Fe cations in natural olivine after thermal treatments in air has... more The transformation mechanism of Fe cations in natural olivine after thermal treatments in air has been studied using mainly 57 Fe Mössbauer spectroscopy. J-Fe 2 O 3 nanoparticles appear as the primary Fe 3+ phase in Mössbauer spectra of olivine samples heated at 600-900 °C. These nanoparticles are thermally unstable and they are transformed to D-Fe 2 O 3 with the increase of heating time. Another transformation mechanism of iron related with the complete decomposition of olivine structure has been observed at temperatures of 1000 °C and higher. The mixed oxide MgFe 2 O 4 with the spinel structure and enstatite MgSiO 3 were identified as iron-bearing decomposition products.

Czechoslovak Journal of Physics - CZECH J PHYS, 2001

The thermal decomposition of almandine garnet from Zoltye Vody, Ukraine, has been studied using57... more The thermal decomposition of almandine garnet from Zoltye Vody, Ukraine, has been studied using57Fe M�ssbauer spectroscopy. Room temperature M�ssbauer spectrum of the initial powdered sample is characterised by one doublet corresponding to Fe2+ in dodecahedral position 24c. In the room temperature spectra of all heated almandine samples, a doublet corresponding to γ-Fe2O3 nanoparticles appeared. Depending on experimental conditions (heating temperature and time), the additional spectral lines of α-Fe2O3 and ε-Fe2O3 were observed in M�ssbauer spectra. It is obvious that the thermal transformation of almandine garnet in air is related to the primary formation of γ-Fe2O3 superparamagnetic nanoparticles. γ-Fe2O3 nanoparticles are transformed into ε-Fe2O3 and consequently into α-Fe2O3 at higher temperatures. The mechanism and kinetics of the individual structural transformations depend on experimental conditions — mainly on the heating temperature and size of the particles.

Surface and Interface Analysis, 2006

ABSTRACT An effect of the enamel ageing on the mechanical properties and composition of the steel... more ABSTRACT An effect of the enamel ageing on the mechanical properties and composition of the steel-enamel system was monitored by means of conversion electron and transmission Mössbauer spectroscopy, electron-microprobe analysis, thermogravimetry and microhardness measurement. Two enamels differing in the time delay between their preparation and application on the steel surface (1 day vs 30 days) were used for this comparative study. After the enamelling procedure, the qualitative phase composition of both samples is similar, including α-Fe, FeO, Fe3O4, α-Fe2O3, Fe2SiO4 and the FeNi particles. Despite this similar qualitative phase composition of differently aged enamels, the mechanical properties of the samples are significantly different. Copyright © 2006 John Wiley & Sons, Ltd.

Surface and Coatings Technology, 2006

Mössbauer spectroscopy in transmission geometry, performed simultaneously with conversion X-ray, ... more Mössbauer spectroscopy in transmission geometry, performed simultaneously with conversion X-ray, and conversion electron Mössbauer spectroscopy, X-ray powder diffraction and electron microprobe analysis (EMPA), have been used to monitor the effects of a chemical pre-treatment on the phase composition of a “steel–enamel interface” of a hot-rolled steel surface formed during a thermally induced coating process. In this comparative study, we have

Physics and Chemistry of Minerals, 2003

The mechanism of thermally induced oxidation of Fe 2+ from natural pyrope has been studied at 100... more The mechanism of thermally induced oxidation of Fe 2+ from natural pyrope has been studied at 1000 and 1100°C using 57 Fe Mo¨ssbauer spectroscopy in conjunction with XRD, XRF, AFM, QELS, TG, DTA and electron microprobe analyses. At 1000°C, the nondestructive oxidation of Fe 2+ in air includes the partial stabilization of Fe 3+ in the dodecahedral 24c position of the garnet structure and the simultaneous formation of hematite particles (15-20 nm). The incorporation of the magnesium ions to the hematite structure results in the suppression of the Morin transition temperature to below 20 K. The general garnet structure is preserved during the redox process at 1000°C, in accordance with XRD and DTA data. At 1100°C, however, oxidative conversion of pyrope to the mixed magnesium aluminium iron oxide, Fe-orthoenstatite and cristoballite was observed. During this destructive decomposition, Fe 2+ is predominantly oxidized and incorporated into the spinel structure of Mg(Al,Fe) 2 O 4 and partially stabilized in the structure of orthoenstatite, (Mg,Fe)SiO 3. The combination of XRD and Mo¨ssbauer data suggest the definite reaction mechanism prevailing, including the refinement of the chemical composition and quantification of the reaction products. The reaction mechanism indicates that the respective distribution of Fe 2+ and Fe 3+ to the enstatite and spinel structures is determined by the total content of Fe 2+ in pyrope. Keywords Fe-bearing garnet AE Mo¨ssbauer spectroscopy AE Oxidation mechanism AE Decomposition products AE Alpha Fe 2 O 3

Hyperfine Interactions, 2000

The natural garnets from almandine (Fe 3 Al 2 Si 3 O 12)-pyrope (Mg 3 Al 2 Si 3 O 12) series with... more The natural garnets from almandine (Fe 3 Al 2 Si 3 O 12)-pyrope (Mg 3 Al 2 Si 3 O 12) series with the iron to magnesium atomic ratio ranging from 0.2 to 1 were characterised and their thermal behaviour at 1200 • C studied by 57 Fe Mössbauer spectroscopy, X-ray powder diffraction, X-ray fluorescence, DTA, TG and electron microprobe analysis. The pyrope-type samples with a dominant magnesium content at position 24c in the cubic garnet structure undergo oxidative decomposition at 1200 • C resulting in the formation of the paramagnetic spinel Mg(Al,Fe) 2 O 4 structure with a low iron content, enstatite (Mg,Fe)SiO 3 and anorthite CaAl 2 Si 2 O 8 as the host compound for calcium. Contrary to pyropes, the iron-rich garnets exhibit complete oxidation at 1200 • C conforming to the formation of magnetically ordered nanocrystalline γ-Fe 2 O 3 or Mg(Fe,Al) 2 O 4 spinels depending on the initial chemical composition of the garnets. In the reaction products of iron-rich garnets, cordierite (Mg 2 Al 4 Si 5 O 18) and anorthite were identified as non-ferrous phases.

Czechoslovak Journal of Physics, 2006

® 2.1 Preparation of the samples ® 2.2 Sample characterisation 3.Results and discussion 4.Conclus... more ® 2.1 Preparation of the samples ® 2.2 Sample characterisation 3.Results and discussion 4.Conclusion 11.-15.6.2006

ABSTRACT An effect of the enamel ageing on the mechanical properties and composition of the steel... more ABSTRACT An effect of the enamel ageing on the mechanical properties and composition of the steel-enamel system was monitored by means of conversion electron and transmission Mössbauer spectroscopy, electron-microprobe analysis, thermogravimetry and microhardness measurement. Two enamels differing in the time delay between their preparation and application on the steel surface (1 day vs 30 days) were used for this comparative study. After the enamelling procedure, the qualitative phase composition of both samples is similar, including α-Fe, FeO, Fe3O4, α-Fe2O3, Fe2SiO4 and the FeNi particles. Despite this similar qualitative phase composition of differently aged enamels, the mechanical properties of the samples are significantly different. Copyright © 2006 John Wiley & Sons, Ltd.