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Wyświetlanie 1-12 z 12
Tytuł:
Effect of synthesis parameters of graphene/Fe₂O₃ nanocomposites on their structural and electrical conductivity properties
Autorzy:
Jędrzejewska, A.
Sibera, D.
Narkiewicz, U.
Pełech, R.
Jędrzejewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1055069.pdf
Data publikacji:
2017-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.48.Gh
65.80.Ck
81.07.Bc
Opis:
Due to its fascinating properties such as high surface area, very good electrical and thermal conductivity, excellent mechanical properties, optical and electrochemical properties, graphene may be the ideal material as a substrate of nanocomposites for applications in electronics. Graphene layer can be used as a conductive matrix allowing good contact between crystallites of nanomaterials. Despite pure graphene, its composites with other species can be of interest. In this paper the results of studies on the effect of methods and parameters of synthesis, for obtaining composites graphene/Fe₂O₃ on their structural properties and electrical properties are presented. A series of experiments was conducted using a commercially available graphene (Graphene Nanopowder AO-3) and iron nitrate. The materials were obtained using two pressure methods: pressure synthesis in the autoclave and synthesis in the microwave solvothermal reactor. The syntheses were carried out in a solution of ethanol. The specific surface area, helium density, morphology, phase composition, thermal properties and electric conductivity of the obtained composites were investigated.
Źródło:
Acta Physica Polonica A; 2017, 132, 4; 1424-1429
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanocomposites graphene/CoFe2O4 and graphene/NiFe2O4 – preparation and characterization
Autorzy:
Jędrzejewska, A.
Sibera, D.
Pełech, R.
Jedrzejewski, R.
Narkiewicz, U.
Powiązania:
https://bibliotekanauki.pl/articles/352113.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
graphene
nanocomposites
CoFe2O4
NiFe2O4
Opis:
A series of nanocomposite graphene/CoFe2 O4 and graphene/NiFe2 O4 hybrid materials was synthesized via facile, one-pot solvothermal route. The materials were obtained using two pressure methods: synthesis in the autoclave and synthesis in the microwave solvothermal reactor. The use of a microwave reactor enabled to significantly shorten the synthesis time up to 15 min. All the syntheses were carried out in a solution of ethanol. The effect of processing conditions and composite composition on the physicochemical properties and electric conductivity was studied. The specific surface area, density, morphology, phase composition, thermal properties and electric conductivity of the obtained composites were investigated. The results of studies of composites obtained in an autoclave and in a microwave reactor were compared.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 1; 103-112
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Resonance Study of MnO/ZnO Nanopowders
Autorzy:
Guskos, N.
Zolnierkiewicz, G.
Typek, J.
Sibera, D.
Narkiewicz, U.
Łojkowski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1492782.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
76.30.Fc
76.50.+g
Opis:
Fine particles n(MnO)/-(1-n)ZnO (n = 0.05 to 0.95) were prepared by wet chemistry method. According to X-ray diffraction analysis the obtained samples with n = 0.95, 0.90, 0.80, 0.70, 0.60 contained $Mn_3O_4$ and $ZnMn_2O_4$ phases, while samples with n = 0.05, 0.10, 0.20, 0.30, 0.40 and 0.50 contained $ZnMnO_3$ and ZnO phases. The mean crystalline size of $ZnMnO_3$ varied from 8 to 13 nm. The magnetic resonance investigations have been carried out at room temperature. Slightly asymmetric, broad and intense magnetic resonance line is recorded for all samples. The magnetic resonance spectra parameters showed marked differences depending on the composition index n. This could be explained by the variation of the magnetic susceptibility and a much slower evolution of spin relaxation, associated with the interaction of crystal field and superexchange interactions. Taking into account the values of magnetic resonance parameters, the investigated samples could be divided into two groups: these with the composition index n<0.50 and those with n>0.50. A detailed discussion of the magnetic properties of different phases in the n(MnO)/-(1-n)ZnO system is presented.
Źródło:
Acta Physica Polonica A; 2011, 120, 6; 1074-1079
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of ZnO Doped with $Fe_{2}O_{3}$ - Hydrothermal Synthesis and Calcination Process
Autorzy:
Sibera, D.
Jędrzejewski, R.
Mizeracki, J.
Presz, A.
Narkiewicz, U.
Łojkowski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1807546.pdf
Data publikacji:
2009-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.-w
68.37.Hk
81.07.-b
81.16.Be
Opis:
The aim of the present work is to compare two methods of synthesis of nanocrystallline zinc oxide doped with iron oxide. The synthesis was carried out using microwave asssisted hydrothermal synthesis and traditional wet chemistry method followed by calcination. The phase composition of the samples was determined using X-ray diffraction measurements. Depending on the chemical composition of the samples, hexagonal ZnO, and/or cubic $ZnFe_{2}O_{4}$ were identified. The morphology of the received materials was characterized using scanning electron microscopy. Two different structures of agglomerates were observed: a hexagonal structure (corresponding to zinc oxide) and spherical (corresponding to spinel phase). The effect of the iron oxide concentration on specific surface area and density of the samples was determined.
Źródło:
Acta Physica Polonica A; 2009, 116, S; S-133-S-135
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
FMR Study of Temperature Dependence of Magnetic Properties of Nanocrystalline $0.90(Fe_2O_3)$/0.10ZnO
Autorzy:
Guskos, N.
Glenis, S.
Zolnierkiewicz, G.
Typek, J.
Sibera, D.
Narkiewicz, U.
Powiązania:
https://bibliotekanauki.pl/articles/1492781.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
76.30.Fc
76.50.+g
Opis:
The nanocrystalline mixed system $0.90(Fe_2O_3)$/-0.10ZnO has been prepared by coprecipitation and calcination processes. The phase composition of samples was determined by X-ray diffraction. The studied nanocrystalline sample is dominated by phase $Fe_2O_3$ but very small amounts of ZnO and $ZnFe_2O_4$ phases were also identified. The ferromagnetic resonance investigations of the obtained sample have been carried out in the temperature range from liquid helium to room temperature. The asymmetrical and very intense magnetic resonance line was recorded at all temperatures. A significant shift of spectra towards lower magnetic fields with decreasing temperature was observed. A very good fitting by two Lorentzian functions has been obtained which suggested the existence of a strong anisotropic magnetic interaction. Some similarities in behaviour of ferromagnetic resonance parameters of the present sample and the $0.95Fe_2O_3Fe2O3$/0.05ZnO sample were noticed but the parameters values were essentially different. The gradients Δ $H_{r}$/Δ T (where $H_{r}$ is the resonance field), the broadening processes of the resonance lines as well as the line amplitudes were changing more intensely changing with temperature in comparison to sample $0.95Fe_2O_3Fe2O3$/0.05ZnO. The following values Δ $H_{r}$/Δ T are obtained: 16.7(1) Gs/K and 20.7(1) Gs/K over the 60 K temperatures where below 40 K is 41.5(1) Gs/K and 56.0(1) Gs/K. The reorientation processes were more active at low temperatures for smaller concentrations of magnetic nanoparticles.
Źródło:
Acta Physica Polonica A; 2011, 120, 6; 1070-1073
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis by Wet Chemical Method and Characterization of Nanocrystalline ZnO Doped with $Fe_2O_3$
Autorzy:
Narkiewicz, U.
Sibera, D.
Kuryliszyn-Kudelska, I.
Kilański, L.
Dobrowolski, W.
Romčević, N.
Powiązania:
https://bibliotekanauki.pl/articles/1812407.pdf
Data publikacji:
2008-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
75.75.+a
78.67.Bf
Opis:
Nanocrystalline samples of ZnO doped with $Fe_2O_3$ were synthetized by wet chemical method. The series of ZnO nanosized samples in the wide range of $Fe_2O_3$ concentration (from 5 wt.% to 95 wt.%) was prepared by precipitation from nitrate solutions using ammonia. The phase composition of the samples was determined using X-ray diffraction measurements. The phases of hexagonal ZnO, and/or rhombohedric $Fe_2O_3$, and/or $ZnFe_2O_4$ were identified. The mean crystalline size of nanocrystals, determined with the use of Scherrer's formula, varied from 8 to 52 nm. The preliminary micro-Raman spectroscopy measurements were performed. The observed features are typical of Fe doped ZnO nanoparticles. The magnetic measurements revealed the presence of different types of magnetic behavior. For samples with high $Fe_2O_3$ contents (above 70 wt.%) the ferromagnetic ordering was observed at room temperature. For samples with lower $Fe_2O_3$ contents we observed the phenomenon of superparamagnetism above the blocking temperature.
Źródło:
Acta Physica Polonica A; 2008, 113, 6; 1695-1700
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoluminescence and Chromaticity Properties of ZnO Nanopowders Made by a Microwave Hydrothermal Method
Autorzy:
Wolska, E.
Sibera, D.
Witkowski, B.
Yatsunenko, S.
Pełech, I.
Narkiewicz, U.
Godlewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1492917.pdf
Data publikacji:
2011-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.-n
61.43.Gt
81.07.Wx
78.55.Et
Opis:
Four series of ZnO nanopowders obtained by a microwave hydrothermal method are examined. Two different solvents (ethanol and distilled water) and different values of pressure during heating in the reactor were used. The obtained nanopowders show a bright emission covering visible light spectral region, including the band edge emission. Results of scanning electron microscopy, X-ray diffraction, photo- and cathodoluminescence investigations and also CIE1961 chromaticity diagram are presented.
Źródło:
Acta Physica Polonica A; 2011, 120, 5; 908-910
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nano-ZnAl2O4 - hydrothermal mw assisted synthesis in a stop-flow reactor and characterization
Synteza w mikrofalowym reaktorze typu stop-flow oraz charakteryzacja spinelu nano-ZnAl2O4
Autorzy:
Sibera, D.
Strachowski, T.
Łojkowski, W.
Narkiewicz, U.
Chudoba, T.
Jędrzejewski, R.
Majcher, A.
Presz, A.
Powiązania:
https://bibliotekanauki.pl/articles/257920.pdf
Data publikacji:
2010
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Technologii Eksploatacji - Państwowy Instytut Badawczy
Tematy:
ZnAl2O4
synteza hydrotermalna
reaktor przemysłowy
hydrothermal synthesis
flow reactor
Opis:
The aim of the study was to obtain nanometric zinc-alumina spinel in a stop-flow reactor with microwave emission. The water solution of zinc and aluminium nitrates was used as a reaction substrate. The mole ratio of Al:Zn = 2:1. A 2M water solution of potassium hydroxide was used as mineraliser. The process was carried out under the pressure of 3.9 MPa for 15, 30 and 60 min. The obtained product had grains of about 6 nm, determined on the basis of the specific surface area and density measurements, observed using SEM and TEM microscopes. According to XRD analysis, a pure phase of Al-Zn spinel was obtained for optimum reaction time of 30 min. The specific surface area measured using BET method was in the range of 230-270 m2/g. For the first time a nanocrystalline zinc aluminate spinel of high specific surface area and high phase purity was obtained in a stop flow microwave solvothermal reactor.
Celem prac było uzyskanie manometrycznego spineklu cynkowo-aluminiowego w mikrofalowym reaktorze pracującym w cyklu stop-flow. Jako substratów reakcji użyto azotków cynku i aluminium w stosunku molowym Al:Zn = 2:1. Jako mineralizator zastosowano 2M wodny roztwór wodorotlenku potasu. Procesy prowadzone były przy ciśnieniu 3.9 MPa przez 15, 30 i 60 minut. Otrzymano produkt o rozmiarze ziaren około 6 nm. Rozmiar ziaren określono z wykorzystaniem pomiarów powierzchni właściwej i gęstości oraz obserwacji wykonywanych z użyciem mikroskopów SEM i TEM. Przepro-wadzona analiza XRD wykazała, że czystą fazę Al-Zn uzyskano dla czasu reakcji wynoszącego 30 minut. Powierzchnia właściwa, określona metodą BET, zawierała się w zakresie 230-270 m2/g. Po raz pierwszy uzyskano, w reaktorze mikrofalowym typu stop-flow, nanokrystaliczny spinel cynkowo-aluminiowy o dużej powierzchni właściwej i dużej czystości fazowej.
Źródło:
Problemy Eksploatacji; 2010, 4; 91-102
1232-9312
Pojawia się w:
Problemy Eksploatacji
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Scattering from ZnO(Fe) Nanoparticles
Autorzy:
Romčević, N.
Kostić, R.
Romčević, M.
Hadžić, B.
Kuryliszyn-Kudelska, I.
Dobrowolski, W.
Narkiewicz, U.
Sibera, D.
Powiązania:
https://bibliotekanauki.pl/articles/1811980.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.-e
78.30.Fs
78.67.-n
Opis:
Nanocrystalline samples of ZnO(Fe) were synthesized by wet chemical method. Samples were characterized by X-ray diffraction to determine composition of the samples (ZnO, Fe₂O₃, ZnFe₂O₄) and the mean crystalline size (8-52 nm). In this paper we report the experimental spectra of the Raman scattering (from 200 to $1600 cm^{-1}$). Main characteristics of experimental Raman spectrum in 200 to $1600 cm^{-1}$ spectral region are: sharp peak at $436 cm^{-1}$ and broad two-phonon structure at ≈ $1150 cm^{-1}, typical of ZnO;broad structure below $700 cm^{-1}$ that has different position and shape in case of ZnFe₂O₄ or Fe₂O₃ nanoparticles.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1323-1328
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanocrystalline ZnO Doped with Fe$\text{}_{2}$O$\text{}_{3}$ - Magnetic and Structural Properties
Autorzy:
Kuryliszyn-Kudelska, I.
Hadžić, B.
Sibera, D.
Kilanski, L.
Romčević, N.
Romčević, M.
Narkiewicz, U.
Dobrowolski, W.
Powiązania:
https://bibliotekanauki.pl/articles/2048113.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
81.05.Dz
75.50.Lk
75.50.Vv
Opis:
We have studied the magnetic properties of ZnO nanocrystals doped with Fe$\text{}_{2}$O$\text{}_{3}$ in the magnetic dopant range from 5 to 70 wt%. The nanocrystals were synthesized by wet chemical method. The detailed structural characterization was performed by means of X-ray diffraction and micro-Raman spectroscopy measurements. The results of systematic measurements of magnetic AC susceptibility as a function of temperature and frequency are presented. We observed different types of magnetic behavior. For ZnO samples doped with low content of Fe$\text{}_{2}$O$\text{}_{3}$, the results of low-field AC susceptibility are satisfactorily explained by superparamagnetic model including inter-particle interactions. With the increase of magnetic Fe$\text{}_{2}$O$\text{}_{3}$ content, the spin-glass-like behavior is observed.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 689-691
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Frequency Raman Scattering from ZnO(Fe) Nanoparticles
Autorzy:
Kostić, R.
Romčević, N.
Romčević, M.
Hadžić, B.
Rudolf, R.
Kuryliszyn-Kudelska, I.
Dobrowolski, W.
Narkiewicz, U.
Sibera, D.
Powiązania:
https://bibliotekanauki.pl/articles/1807817.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Fs
78.67.-n
Opis:
Nanocrystalline samples of ZnO(Fe) were synthesized by wet chemical method. Samples were characterized by X-ray diffraction to determine the sample composition and the mean crystalline size. Low-frequency Raman modes were measured and assigned according to confined acoustic vibrations of spherical nanoparticles. Frequencies of these vibrational modes were analyzed in elastic continuum aproximation, which considers nanoparticle as homogeneous elastic sphere.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 65-67
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Utilization of spent iron catalyst for ammonia synthesis
Autorzy:
Arabczyk, W.
Narkiewicz, U.
Lendzion-Bieluń, Z.
Moszyński, D.
Pełech, I.
Ekiert, E.
Podsiadły, M.
Pelka, R.
Jędrzejewski, R.
Moszyñska, I.
Sibera, D.
Powiązania:
https://bibliotekanauki.pl/articles/778207.pdf
Data publikacji:
2007
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
katalizator żelazowy
azotki żelaza
nanorurka węglowa
nanowłókna
iron catalyst
iron nitrides
carbon nanotubes
nanofibers
Opis:
Several methods of the utilization of spent iron catalyst for ammonia synthesis have been presented. The formation of iron nitrides of different stoichiometry by direct nitriding in ammonia in the range of temperatures between 350°C and 450°C has been shown. The preparation methods of carbon nanotubes and nanofibers where iron catalyst catalyse the decomposition of hydrocarbons have been described. The formation of magnetite embedded in a carbon material by direct oxidation of carburized iron catalyst has been also presented.
Źródło:
Polish Journal of Chemical Technology; 2007, 9, 3; 108-113
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-12 z 12

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