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Wyświetlanie 1-7 z 7
Tytuł:
Preparation of carbon nanomaterials over Ni/ZSM-5 catalyst using simplex method algorithm
Autorzy:
Majewska, J.
Michalkiewicz, B.
Powiązania:
https://bibliotekanauki.pl/articles/1075535.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.De
81.16.Hc
81.15.Gh
Opis:
Carbon nanomaterials were prepared from methane by catalytic decomposition over a nickel-supported ZSM-5 catalyst. The mole ratio of SiO₂ to Al₂O₃ in ZSM-5 was 200-400. The nickel content was varied from 17 to 23 wt% Ni. In order to find the greatest yield and the highest quality of carbon nanomaterials the simplex design method for planning the experiments was applied. Different parameters such as: temperature, methane flow, nitrogen flow and nickel content in the catalyst were evaluated. The carbon nanomaterials were analyzed by the Raman spectroscopy, scanning and transmission electron microscopy, and total organic carbon analyzer.
Źródło:
Acta Physica Polonica A; 2016, 129, 1; 153-157
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of dye type on montmorillonite-supported Pr-doped TiO₂ composite photocatalsyt
Autorzy:
Otsukarci, B.
Kalpakli, Y.
Powiązania:
https://bibliotekanauki.pl/articles/1070473.pdf
Data publikacji:
2016-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.16.Hc
87.64.K
87.64.km
Opis:
Scarcity of water in today's world has led to scientific researches for finding smarter ways of discharging and re-using water located in the seas and lakes. That is how advanced oxidation technologies have emerged as one of the new discharging techniques to keep water sources clean. In our method we have synthesized praseodymium (Pr) doped TiO₂-Montmorillonite composite photocatalyst by using acid sol-gel method. Pr, in the group of rare earth metals, is known for its ability to form Lewis bases in order to break down aldehydes, amines, etc., by decreasing the crystal size and consequently increasing the surface area. We have used the mineral form of the bentonite clay (montmorillonite) to increase the surface area of our composite photocatalyst. Two types of azo dyes which are commercially known as Basic Yellow 28 (BY 28) and Basic Blue 41 (BB 41) were used in experimants. These dyes are composed of different chemical structures: BY 28 is known as azomethine dye (-CH=N-), whereas BB 41 has one azo bond (-N=N-). The initial model dye concentrations were 100 ppm. Amount of 1.0 g/l of photocatalyst was used throughout the experiments. In order to evaluate degradation efficiency results, the dissolved organic carbon analyzer was used. We have found the optimum dark adsorption time to be under 15 minutes. By stirring under 15 minutes in the dark we have achieved efficiency of 52.50% for BY 28 and 66.74% for BB 41. On the other hand, by stirring under UV-A light irradiation for two hours we have achieved the overall degradation efficiency of 86.30% for BY 28 and 92.39% for BB 41. Our results show that higher adsorption and overall efficiencies were observed in BB 41 than in BY 28. Moreover, according to Water Pollution Control Regulations, the chemical oxygen demand limitations for textile industry are between 200-400 mg/l. To evaluate the degradation characteristics of Pr-doped TiO₂-Montmorillonite composite, the change of chemical oxygen demand values with time for 100 mg/l of BY 28 and BB 41 were investigated. The obtained chemical oxygen demand values were 60.5 and 34.8 mg O₂/l after 2 hours of oxidation processes for BY 28 and BB 41. As it can be seen from the results, obtained values are below the limitations.
Źródło:
Acta Physica Polonica A; 2016, 130, 1; 198-201
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
GaMnAs: Layers, Wires and Dots
Autorzy:
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1811909.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
62.23.Hj
81.16.Hc
Opis:
Thin layers of GaMnAs ferromagnetic semiconductor grown by molecular beam epitaxy on GaAs(001) substrates were studied. To improve their magnetic properties the post-growth annealing procedures were applied, using the surface passivation layers of amorphous arsenic. This post-growth treatment effectively increases the ferromagnetic-to-paramagnetic phase transition in GaMnAs, and provides surface-rich MnAs layer which can be used for formation of low-dimensional structures such as superlattices. If the surface rich MnAs layer consists of MnAs dots, then it is possible to grow Mn-doped GaAs nanowires.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1001-1012
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Kinetics of Ethylene Decomposition on Iron Catalyst
Autorzy:
Pełech, I.
Narkiewicz, U.
Powiązania:
https://bibliotekanauki.pl/articles/1807641.pdf
Data publikacji:
2009-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.70.Pg
61.05.cp
81.07.Bc
81.16.Hc
Opis:
The effect of ethylene partial pressure and temperature on the hydrocarbon decomposition rate was studied. As a catalyst, a triply promoted iron catalyst (with addition of small amounts of potassium, calcium and alumina oxides) was used. The mean crystallites size was ca. 17 nm. The processes were performed using pure ethylene or ethylene-nitrogen mixture under atmospheric pressure at the temperature range from 400 to 460°C. The growth of carbon mass as a function of reaction time was measured using a thermobalance. The phase composition of the samples after ethylene decomposition was determined using X-ray diffraction technique. The reaction rate was independent of ethylene partial pressure in the range from 0.25 to 1 bar. The maximal carbon yield for given experimental conditions was estimated.
Źródło:
Acta Physica Polonica A; 2009, 116, S; S-146-S-149
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Leaching of Al-Based Polygrain Quasicrystalline and Related Crystalline Surfaces
Autorzy:
Yadav, T.
Mishra, S.
Pandey, S.
Singh, D.
Lowe, M.
Tamura, R.
Mukhopadhyay, N.
Srivastava, O.
McGrath, R.
Sharma, H.
Powiązania:
https://bibliotekanauki.pl/articles/1373698.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.44.Br
81.16.Hc
61.66.Dk
68.37.Hk
Opis:
In the present investigation, we have studied leaching on polygrain Al-based quasicrystalline $(i-Al_{63}Cu_{25}Fe_{12})$ as well as crystalline (B2 phase; $Al_{55}Cu_{30}Fe_{15})$ alloy surfaces using a 10 mole NaOH solution. The surface was leached at varying times from 30 min to 8 h and subsequently characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. Leaching of the samples for 30 min generated a homogeneous layer. However further leaching for 1-8 h yielded nano-size particles on the surface. Spherical microstructure has been observed on the Al-Cu-Fe crystalline surface whereas on the quasicrystalline surface a petal-like microstructure appeared. The implications of the evolution of different microstructures in the context of structure, stability and activity are discussed. The results are compared with the microstructure of leached polygrained samples containing a mixture of different surface orientations.
Źródło:
Acta Physica Polonica A; 2014, 126, 2; 629-632
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrogen Sensors Made on InP or GaN with Electrophoretically Deposited Pd or Pt Nanoparticles
Autorzy:
Zdansky, K.
Cernohorsky, O.
Yatskiv, R.
Powiązania:
https://bibliotekanauki.pl/articles/1418961.pdf
Data publikacji:
2012-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.45.Qr
81.16.Hc
73.61.Ey
73.40.Kp
73.40.Ei
Opis:
High quality Schottky diodes were prepared by printing colloidal graphite on the polished wafers of n-type InP or n-type GaN. The wafers were earlier sparsely covered with palladium or platinum nanoparticles by electrophoresis from prepared colloid solutions in isooctane. Deposited contacts and nanoparticles were observed by scanning electron mictroscopy. Current voltage characteristics of the Schottky diodes showed high rectification ratios and the barrier heights close to the value of vacuum-level-alignment of the Schottky-Mott limit. The sensitivity to hydrogen of the diodes was measured in the flow of hydrogen/nitrogen mixtures of various hydrogen concentrations in the range from 1 ppm to 1000 ppm. The estimated detection limits of the diodes were in the sub-ppm range. The diodes represent orders-of-magnitude improvement over the best hydrogen sensors reported previously.
Źródło:
Acta Physica Polonica A; 2012, 122, 3; 572-575
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
InSb Quantum Dots in an InAsSb Matrix Grown by Molecular Beam Epitaxy
Autorzy:
Semenov, A. N.
Solov'ev, V. A.
Meltser, B. Ya.
Lyublinskaya, O. G.
Terent'ev, Ya. V.
Sitnikova, A. A.
Ivanov, S. V.
Powiązania:
https://bibliotekanauki.pl/articles/2044535.pdf
Data publikacji:
2005-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
78.67.Hc
81.07.Ta
81.15.Hi
81.16.Dn
Opis:
We report on molecular beam epitaxy of InSb insertions in InAs and InAsSb matrices, emitting at wavelengths beyond 4μm. Different growth techniques for deposition of InSb quantum dots in the 1-2 monolayer range of the InSb nominal thickness, namely conventional molecular beam epitaxy and migration enhanced epitaxy, as well as different matrices (InAs and InAsSb) have been employed for increasing the emission wavelength of the InSb/InAs nanostructures. The formation of InSb quantum dots has been studied in situ using reflection high energy electron diffraction and ex situ by using transmission electron microscopy. The peculiarities of In(Ga)AsSb alloys growth and compositional control are also discussed. Bright photoluminescence up to 4.5μm has been observed at 80 K.
Źródło:
Acta Physica Polonica A; 2005, 108, 5; 859-865
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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