J. Gurgul - Academia.edu (original) (raw)

Papers by J. Gurgul

Surface and Interface Analysis, 2016

Physical Review B - Condensed Matter and Materials Physics, 2006

Magnetic properties of the Mott insulator with the pyrochlore structure Y 2 Ru 2 O 7 were investi... more Magnetic properties of the Mott insulator with the pyrochlore structure Y 2 Ru 2 O 7 were investigated using 99 Ru Mössbauer spectroscopy. Bulk magnetization measurements confirmed appearance of the spin-glass-like antiferromagnetic order with very large differences between zero-field-cooled and field-cooled magnetizations below the Néel temperature T N =76͑2͒ K. The Mössbauer spectra were obtained above and below T N. Analysis of the spectrum recorded at 4.2 K suggested a noncollinear local ordering of ruthenium magnetic moments. The electronic structure of the individual ruthenium ion, responsible for magnitudes of hyperfine parameters and the ruthenium magnetic moment, was discussed within the framework of the crystalline electric-field model, including the spin-orbit coupling and the exchange interaction in the molecular-field approximation. Reasonably good agreement between calculated and experimentally determined parameters was obtained. Simultaneously, the experimentally observed easy plane of ruthenium magnetic moments was explained.

Journal of Magnetism and Magnetic Materials, 2006

... Kazimierz Łątka a , E-mail The Corresponding Author , Roman Kmieć b , Jacek Gurgul c , Andrze... more ... Kazimierz Łątka a , E-mail The Corresponding Author , Roman Kmieć b , Jacek Gurgul c , Andrzej W. Pacyna b , Michał Rams a , Tobias Schmidt d ... following parameters were obtained from the fitting procedure: a temperature independent factor χ 0 =5.7(2)×10 −4 Oe emu/mol, a ...

Catalysis Today, 2007

ABSTRACT The influence of the synthesis pH and of the Zn and/or Al additives on the Cu–Mn precurs... more ABSTRACT The influence of the synthesis pH and of the Zn and/or Al additives on the Cu–Mn precursors, obtained by co-precipitation at a constant pH from aqueous solutions of appropriate nitrates at (Cu+Zn)/(Mn+Al) ratio equal 2, was investigated. The relative content of Mn increased with the pH of precipitation. Depending on the sample composition the identified crystalline phases included layered hydroxy double salt, hydrotalcite-like structure, CuO and ZnO. Some precursors had strongly amorphous character. Calcination of the precursors at 673K resulted in mixed oxides, in which CuO of various degrees of crystallinity could be identified. The Mn-containing phases remained amorphous. All calcined materials proved extremely active in catalytic combustion of toluene. Some catalysts reached 100% conversion already at 403K. High conversions observed in the low temperature regime were partially due to the strong sorption of toluene. In the catalysts containing Al additive this effect was suppressed.

Catalysis Letters, 2008

The Cu x SiBEA zeolites prepared by a two-step postsynthesis method are active in selective catal... more The Cu x SiBEA zeolites prepared by a two-step postsynthesis method are active in selective catalytic reduction of NO by ethanol and their catalytic activity is related to the presence of mononuclear Cu(II) species. Zeolite with isolated lattice mononuclear Cu(II) species is active in this reaction with selectivity toward dinitrogen close to 70-90%.

Applied Catalysis B: Environmental, 2009

Applied Catalysis B: Environmental, 2007

The effect of Co content on the catalytic activity of CoSiBEA zeolites in the selective catalytic... more The effect of Co content on the catalytic activity of CoSiBEA zeolites in the selective catalytic reduction (SCR) of NO with ethanol is investigated. The Co x SiBEA zeolites (x = 0.3, 0.7, 3.6 and 6.75 Co wt.%) are prepared by a two-step postsynthesis method which allows to control the introduction of cobalt into zeolite and thus to obtain catalysts with specific Co sites. The nature of the active sites is characterized by XRD, diffuse reflectance UV-vis, H 2-TPR and XPS. The catalytic activity of Co x SiBEA strongly depends on the nature and environment of Co species. Zeolites with isolated lattice tetrahedral Co(II) (Co 0.3 SiBEA and Co 0.7 SiBEA samples) are active in SCR of NO with ethanol with selectivity toward N 2 exceeding 85% for NO conversion from 20 to 70%. When additional isolated extra-lattice octahedral Co(II) species appear (Co 3.6 SiBEA sample), the full oxidation of ethanol by dioxygen becomes a very important reaction pathway. In presence of additional cobalt oxides (Co 6.75 SiBEA sample), the activity and selectivity toward N 2 substantially change and full oxidation of ethanol to CO 2 is the main reaction pathway and full NO oxidation also takes place in the temperature range 550-775 K. The lack of correlation between the activity in SCR of NO with ethanol and NO oxidation to NO 2 suggests that the two reactions are more competitive than sequential.

Applied Catalysis B: Environmental, 2009

Applied Catalysis B: Environmental, 2009

Surface and Interface Analysis, 2010

We report on the structural properties of epitaxial FeO layers grown by molecular beam epitaxy on... more We report on the structural properties of epitaxial FeO layers grown by molecular beam epitaxy on MgO(111). The successful stabilization of polar FeO films as thick as 16 monolayers (ML), obtained by deposition and subsequent oxidation of single Fe layers, is presented. FeO/MgO(111) thin films were chemically and structurally characterized using low-energy electron diffraction, Auger electron spectroscopy and conversion electron Mössbauer spectroscopy (CEMS). Detailed in situ CEMS measurements as a function of the film thickness demonstrated a size-effect-induced evolution of the hyperfine parameters, with the thickest film exhibiting the bulk-wüstite hyperfine pattern. Ex situ CEMS investigation confirmed the magnetic ordering of the wüstite thin film phase at liquid nitrogen temperature.

Nukleonika, 2007

In recent years we have investigated a series of equiatomic intermetallic REAuSn compounds (RE = ... more In recent years we have investigated a series of equiatomic intermetallic REAuSn compounds (RE = rare earth elements) [2, 6−13]. These stannides belong to a large family of equiatomic ternary rare earth compounds, which adopt different crystal structures resulting in a large variety of physical properties [18]. These properties are related to the hybridization between the rare earth 4f-electron states and the conduction electron states. The aim of this report is to review the results of our crystallographic and spectroscopic studies, systematically made for REAuSn series. Especially, Sn Mössbauer spectroscopy, as a microscopic technique, was applied to characterise the local electronic properties of the compounds under investigation. By virtue of the local sensitivity of the Mössbauer probe it is possible to investigate the temperature evolution of hyperfine parameters following structural and magnetic phase transformations.

Applied Catalysis B-environmental, 2009

Microporous and Mesoporous Materials

Microporous and Mesoporous Materials

Theoretical and Experimental Chemistry

Applied Catalysis B: Environmental

Surface and Interface Analysis, 2016

Applied Catalysis A: General, 2016

Surface and Interface Analysis, 2016

Physical Review B - Condensed Matter and Materials Physics, 2006

Magnetic properties of the Mott insulator with the pyrochlore structure Y 2 Ru 2 O 7 were investi... more Magnetic properties of the Mott insulator with the pyrochlore structure Y 2 Ru 2 O 7 were investigated using 99 Ru Mössbauer spectroscopy. Bulk magnetization measurements confirmed appearance of the spin-glass-like antiferromagnetic order with very large differences between zero-field-cooled and field-cooled magnetizations below the Néel temperature T N =76͑2͒ K. The Mössbauer spectra were obtained above and below T N. Analysis of the spectrum recorded at 4.2 K suggested a noncollinear local ordering of ruthenium magnetic moments. The electronic structure of the individual ruthenium ion, responsible for magnitudes of hyperfine parameters and the ruthenium magnetic moment, was discussed within the framework of the crystalline electric-field model, including the spin-orbit coupling and the exchange interaction in the molecular-field approximation. Reasonably good agreement between calculated and experimentally determined parameters was obtained. Simultaneously, the experimentally observed easy plane of ruthenium magnetic moments was explained.

Journal of Magnetism and Magnetic Materials, 2006

... Kazimierz Łątka a , E-mail The Corresponding Author , Roman Kmieć b , Jacek Gurgul c , Andrze... more ... Kazimierz Łątka a , E-mail The Corresponding Author , Roman Kmieć b , Jacek Gurgul c , Andrzej W. Pacyna b , Michał Rams a , Tobias Schmidt d ... following parameters were obtained from the fitting procedure: a temperature independent factor χ 0 =5.7(2)×10 −4 Oe emu/mol, a ...

Catalysis Today, 2007

ABSTRACT The influence of the synthesis pH and of the Zn and/or Al additives on the Cu–Mn precurs... more ABSTRACT The influence of the synthesis pH and of the Zn and/or Al additives on the Cu–Mn precursors, obtained by co-precipitation at a constant pH from aqueous solutions of appropriate nitrates at (Cu+Zn)/(Mn+Al) ratio equal 2, was investigated. The relative content of Mn increased with the pH of precipitation. Depending on the sample composition the identified crystalline phases included layered hydroxy double salt, hydrotalcite-like structure, CuO and ZnO. Some precursors had strongly amorphous character. Calcination of the precursors at 673K resulted in mixed oxides, in which CuO of various degrees of crystallinity could be identified. The Mn-containing phases remained amorphous. All calcined materials proved extremely active in catalytic combustion of toluene. Some catalysts reached 100% conversion already at 403K. High conversions observed in the low temperature regime were partially due to the strong sorption of toluene. In the catalysts containing Al additive this effect was suppressed.

Catalysis Letters, 2008

The Cu x SiBEA zeolites prepared by a two-step postsynthesis method are active in selective catal... more The Cu x SiBEA zeolites prepared by a two-step postsynthesis method are active in selective catalytic reduction of NO by ethanol and their catalytic activity is related to the presence of mononuclear Cu(II) species. Zeolite with isolated lattice mononuclear Cu(II) species is active in this reaction with selectivity toward dinitrogen close to 70-90%.

Applied Catalysis B: Environmental, 2009

Applied Catalysis B: Environmental, 2007

The effect of Co content on the catalytic activity of CoSiBEA zeolites in the selective catalytic... more The effect of Co content on the catalytic activity of CoSiBEA zeolites in the selective catalytic reduction (SCR) of NO with ethanol is investigated. The Co x SiBEA zeolites (x = 0.3, 0.7, 3.6 and 6.75 Co wt.%) are prepared by a two-step postsynthesis method which allows to control the introduction of cobalt into zeolite and thus to obtain catalysts with specific Co sites. The nature of the active sites is characterized by XRD, diffuse reflectance UV-vis, H 2-TPR and XPS. The catalytic activity of Co x SiBEA strongly depends on the nature and environment of Co species. Zeolites with isolated lattice tetrahedral Co(II) (Co 0.3 SiBEA and Co 0.7 SiBEA samples) are active in SCR of NO with ethanol with selectivity toward N 2 exceeding 85% for NO conversion from 20 to 70%. When additional isolated extra-lattice octahedral Co(II) species appear (Co 3.6 SiBEA sample), the full oxidation of ethanol by dioxygen becomes a very important reaction pathway. In presence of additional cobalt oxides (Co 6.75 SiBEA sample), the activity and selectivity toward N 2 substantially change and full oxidation of ethanol to CO 2 is the main reaction pathway and full NO oxidation also takes place in the temperature range 550-775 K. The lack of correlation between the activity in SCR of NO with ethanol and NO oxidation to NO 2 suggests that the two reactions are more competitive than sequential.

Applied Catalysis B: Environmental, 2009

Applied Catalysis B: Environmental, 2009

Surface and Interface Analysis, 2010

We report on the structural properties of epitaxial FeO layers grown by molecular beam epitaxy on... more We report on the structural properties of epitaxial FeO layers grown by molecular beam epitaxy on MgO(111). The successful stabilization of polar FeO films as thick as 16 monolayers (ML), obtained by deposition and subsequent oxidation of single Fe layers, is presented. FeO/MgO(111) thin films were chemically and structurally characterized using low-energy electron diffraction, Auger electron spectroscopy and conversion electron Mössbauer spectroscopy (CEMS). Detailed in situ CEMS measurements as a function of the film thickness demonstrated a size-effect-induced evolution of the hyperfine parameters, with the thickest film exhibiting the bulk-wüstite hyperfine pattern. Ex situ CEMS investigation confirmed the magnetic ordering of the wüstite thin film phase at liquid nitrogen temperature.

Nukleonika, 2007

In recent years we have investigated a series of equiatomic intermetallic REAuSn compounds (RE = ... more In recent years we have investigated a series of equiatomic intermetallic REAuSn compounds (RE = rare earth elements) [2, 6−13]. These stannides belong to a large family of equiatomic ternary rare earth compounds, which adopt different crystal structures resulting in a large variety of physical properties [18]. These properties are related to the hybridization between the rare earth 4f-electron states and the conduction electron states. The aim of this report is to review the results of our crystallographic and spectroscopic studies, systematically made for REAuSn series. Especially, Sn Mössbauer spectroscopy, as a microscopic technique, was applied to characterise the local electronic properties of the compounds under investigation. By virtue of the local sensitivity of the Mössbauer probe it is possible to investigate the temperature evolution of hyperfine parameters following structural and magnetic phase transformations.

Applied Catalysis B-environmental, 2009

Microporous and Mesoporous Materials

Microporous and Mesoporous Materials

Theoretical and Experimental Chemistry

Applied Catalysis B: Environmental

Surface and Interface Analysis, 2016

Applied Catalysis A: General, 2016