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Wyszukujesz frazę "81.07.+b" wg kryterium: Temat


Tytuł:
Measurement and Analysis of the Positron Annihilation Lifetime Spectra for Mesoporous Silica
Autorzy:
Zaleski, R.
Powiązania:
https://bibliotekanauki.pl/articles/2047164.pdf
Data publikacji:
2006-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
36.10.Dr
61.43.Gt
81.07.-b
41.75.Fr
Opis:
Positron annihilation lifetime spectroscopy as a technique of porous materials investigation is still under development. Both measurement conditions and lifetime spectra analysis methods have to be adapted to the requirements of positron porosimetry. If complex positron annihilation lifetime spectra of porous materials are processed, numerical methods of lifetime spectra analysis have to be used with a particular care. Among various methods of positron annihilation lifetime spectra analysis available, the most popular ones were tested implemented in programs MELT and LT. It was found, from the simulated spectra study, that a large number of counts in a spectrum is needed to obtain reliable results of analysis. Even then only an approximate solution is available. Determination of the approximation nature helps in a further interpretation of the results and in positron annihilation lifetime spectrometer setting adequate to the problem. For this purpose, a few complex spectra obtained from positron beam facility were tested. The results show a negligible influence of resolution function on long lifetime components, while the precise estimation of the background level is crucial. Also some distortions caused by imperfection of numerical analysis methods are pointed out.
Źródło:
Acta Physica Polonica A; 2006, 110, 5; 729-738
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Porosimetry Studies of Template Removal from As-Synthesized MCM-41 Silica
Autorzy:
Zaleski, R.
Wawryszczuk, J.
Powiązania:
https://bibliotekanauki.pl/articles/1812554.pdf
Data publikacji:
2008-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
36.10.Dr
61.43.Gt
81.07.-b
Opis:
The course of template removal from MCM-41 pores was investigated by positron annihilation lifetime spectroscopy. Two methods of removal were the object of interest: a decarbonisation after standard calcination procedure and a novel procedure - pyrolysis in vacuum. The shapes of positron lifetime spectra of decarbonised sample are determined by positronium quenching caused by presence of carbon deposit on the surface. Positron annihilation lifetime spectroscopy allows also monitoring the evolution of empty space inside pores. During pyrolysis no conductive carbon is produced, so consecutive stages of template material transformation are easy to observe. In the case of pyrolysis the effect of pore emptying is obtained at temperature 500 K, lower comparing to calcination and decarbonisation (820 K).
Źródło:
Acta Physica Polonica A; 2008, 113, 5; 1543-1550
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
NdFeB Permanent Magnets with Various Nd Content
Autorzy:
Žák, T.
Talijan, N.
Ćosović, V.
Grujić, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813649.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.cp
76.80.+y
75.50.-y
81.07.-b
81.40.Rs
Opis:
Three kinds of commercial Nd-Fe-B based materials were compared using $\text{}^{57}Fe$ Mössbauer spectroscopy and X-ray analysis: near the $Nd_2Fe_{14}B$ stoichiometry and with both lowered and raised Nd content. Magnetically hard $Nd_2Fe_{14}B$ is present in all three materials. In the Nd-low material it is accompanied with the magnetically soft $Fe_3B$ phase, building the nanocomposite structure. In the Nd-rich sample the overstoichiometric Nd atoms seem to build separate phase of Fe-Nd solid solution. None of the materials contain significant content of phases degrading magnetic characteristics, with except of minor $Nd_{1.1}Fe_4B_4$ one.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 279-282
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Properties of ZnO Nanopowders Synthesized by Glycine-Nitrate Gel Combustion
Autorzy:
Yıldız, Ö.
Soydan, A.
Ipçizade, E.
Akın, D.
Uçak, Ö.
Powiązania:
https://bibliotekanauki.pl/articles/1311836.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ka
81.07.Wx
61.46.Df
81.07.-b
Opis:
The morphology and other physical properties of ZnO nanopowders synthesized by glycine-nitrate gel combustion process were investigated and characterized by scanning electron microscopy, transmission electron microscopy, nanosizer and X-ray diffraction. Glycine, $NH_2CH_2COOH$, and zinc nitrate $Zn(NO_3)_2$·$6H_2O$ were dissolved in distilled water and the solution was coagulated by mixing at 90°C. The viscous gel prepared during glycine-nitrate mixing was heated at ≈220C to initiate the exothermic reactions by self-combustion where the temperature reached up to 1200°C. The glycine-nitrate ratio had a significant effect on the reaction temperature and final particle morphology. Therefore the synthesized powders have a different morphology like formless and spherical tufa ash. The particle size distribution was 50-1200 nm as measured using a nanosizer.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 664-666
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Analysis of Ce Doped $La_{1-x}Sr_xCo_{1-y}Fe_yO_{3-δ}$ Nanopowders Synthesized by Glycine-Nitrate Gel Combustion
Autorzy:
Yildiz, Ö.
Soydan, A.
Ata, A.
İpçızade, E.
Akin, D.
Uçak, Ö.
Powiązania:
https://bibliotekanauki.pl/articles/1312023.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Wx
81.07.-b
81.20.Ka
88.30.pn
Opis:
Ce doped $La_{1-x}Sr_xCo_{1-y}Fe_yO_3$ (LCSCF) is a widely used cathode material due to its high catalytic activity for oxygen reduction and high oxygen exchange coefficient. LCSCF is also known with its high ionic and electronic conductivities and low electrode polarization losses which are highly critical properties for low temperature solid oxide fuel cell applications. In this study, structural properties of the LCSCF cathode nanopowder materials synthesized by glycine-nitrate gel combustion have been investigated by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and nanosizer. Synthesized nanopowders represent volcanic ash like structures and morphologies. Ce, Sr, Co, and Fe are found to have significant effects on the structural properties of powders in terms of powders morphology, agglomerate structure, crystallite size and also lattice parameter of perovskite crystal. All synthesized ash powders have particle sizes around 50-600 nm, varying crystalline structures of perovskite and fluorite depending on molar ratio of Ce in the composition. Increasing molar Ce ratio over 0.4 is found to lead to the formation of a separate nano ceria phase in fluorite crystal structure on the surface of the synthesized powder.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 669-672
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Particle Impact Angle, Erodent Particle Size and Acceleration Pressure on the Solid Particle Erosion Behavior of 3003 Aluminum Alloy
Autorzy:
Yıldıran, Y.
Avcu, E.
Şahin, A.
Fidan, S.
Yetiştiren, H.
Sınmazçelik, T.
Powiązania:
https://bibliotekanauki.pl/articles/1195082.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Bx
81.70.-q
68.35.B-
68.35.-p
42.79.Ls
68.37.Hk
07.85.Nc
Opis:
This study aims to examine solid particle erosion behavior of 3003 aluminum alloy. 3003 aluminum alloy samples were eroded in erosion test rig under various particle impingement angles (15°, 30°, 45° and 60°) and acceleration pressures (1.5, 3 and 4 bar) by using 80 mesh and 180 mesh sized erodent particles (garnet). The erosion rates of aluminum alloy samples were calculated depending on the erosion parameters. The erosion rates of the samples have varied dramatically depending on particle impingement angle, acceleration pressure and erodent particle size. The maximum erosion rates were observed at 15° impingement angles at all acceleration pressures and particle sizes. Moreover, erosion rates of the samples were increased with increases in acceleration pressure at all particle impingement angles and particle sizes. On the other hand, erosion rates of the samples decrease with increase in erodent particle sizes. Hence, maximum erosion was observed when the aluminum alloy eroded at 15° impingement angle and 4 bar pressure by using 180 mesh erodent particles. Finally, the eroded surfaces of the samples were analyzed by using scanning electron microscope. The surfaces of the samples were also investigated by using energy dispersive X-ray analysis in scanning electron microscopy studies. Microcutting and microploughing erosion mechanisms were observed at 15° and 30° impingement angles, while deep cavities and valleys formed due to plastic deformation were observed at 45° and 60° impingement angles. Moreover, embedded erodent particles were clearly detected on the surfaces of the samples by energy dispersive X-ray analysis.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 523-525
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoluminescence Studies of Aluminum Nitride Nanowires
Autorzy:
Yang, J.
Na, H.
Kim, H.
Kebede, M.
Choi, R.
Jeong, J.
Lee, C.
Powiązania:
https://bibliotekanauki.pl/articles/1505466.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
78.55.-m
Opis:
We report the production of AlN nanowires by the thermal heating method, for exploring their photoluminescence properties. The room-temperature photoluminescence properties were investigated with different annealing environment. While broad emissions with peaks at around 2.45 and 2.95 eV were obtained from both unannealed and annealed samples, the additional 2.1 eV peak was found from the annealed samples. We have suggested the possible emission mechanisms based on the assumption that both 2.45 eV peak and 2.1 eV peak are ascribed to the nitrogen vacancies. Annealing in N_2 environment exhibited lower intensities of 2.45 eV peak and 2.1 eV peak in comparison to those in Ar environment, presumably due to the suppression of nitrogen vacancies.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 125-127
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solvent effects on the optical properties of PEG-SH and CTAB capped gold nanorods
Autorzy:
Wielgus, M.
Gordel, M.
Samoć, M.
Bartkowiak, W.
Powiązania:
https://bibliotekanauki.pl/articles/1058757.pdf
Data publikacji:
2016-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.-e
81.05.Bx
81.07.-b
Opis:
Cetyltrimethylammonium bromide (CTAB) and (11-mercaptoundecyl)tetra(ethylene glycol) (PEG-SH) capped gold nanorods were prepared and dispersed in water and dimethyl sulfoxide (DMSO). Transmission electron microscopy images reveal that changing the solvent from water to DMSO cause that nanoparticles tend to organize (PEG-SH ligand) or aggregate (CTAB ligand). UV-vis absorbance spectra reveal that ligand as well as solvent exchange cause positive solvatochromic shifts and changes in the relative extinction values. After the transfer of nanorods from a solvent of lower to higher refraction index a red shift of the longitudinal surface plasmon resonance band is observed. This effect is more pronounced in the case of PEG-SH capped nanorods. Time resolved pump-probe measurements revealed that both ligand and solvent exchange influence the excited state relaxation times, however, a more pronounced change is induced by the ligand exchange. Two-photon excited fluorescence spectra of PEG-SH covered nanorods showed a slight intensity increase when moving from water to DMSO solvent.
Źródło:
Acta Physica Polonica A; 2016, 130, 6; 1380-1384
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The NO₂ Sensing Properties of the Sensors Done with Nano-Tetrapods
Autorzy:
Tulun, F.
Öztürk, S.
Öztürk, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1398786.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
81.16.-c
81.10.Fq
07.07.Df
81.10.St
Opis:
In this work we have studied the NO2 sensing properties of the sensors with tetrapods. The tetrapods that were used in the production were obtained by CVD route, and their structural analysis was carried out using SEM, XRD and EDX methods. The sensors were produced by a different method that the one mentioned in our another work, and additional electrical I-V characterization was carried out. As well as in the previous work the sensors were tested for 50 ppm sensitivity, by using computer controlled gas flux system, in NO₂ at 200°C, and in ambient air to model the normal working conditions more closely. It was found that the sensors have a good sensitivity to the NO₂ gas. All of the sensors showed a great reversibility and it was found that the recovery time was perfectly low. After this experiment the same sensors were tested with other different gases for several times. And no other problems in sensing ability were seen.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 797-799
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanochemical Synthesis of Silver Chloride Nanoparticles by a Dilution Method in the System $NH_4Cl-AgNO_3-NH_4NO_3$
Autorzy:
Tatykaev, B.
Burkitbayev, M.
Uralbekov, B.
Urakaev, F.
Powiązania:
https://bibliotekanauki.pl/articles/1375636.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Wx
81.07.-b
Opis:
This study presents the results of the synthesis of silver chloride nanoparticles dispersed within ammonium nitrate matrix via displacement mechanochemical reaction $NH_{4}Cl$ + $AgNO_{3}$ + $zNH_{4}NO_{3}$ = $(z+1)NH_{4}NO_{3}$ + AgCl at z = $z_{1}$= 7.22 and z = $z_{2}$= 3.64. The intermediate compound, $NH_{4}Ag(NO_{3})_{2}$, was identified after mechanochemical processing of studied system. Use of simultaneous thermogravimetry and differential scanning calorimetry provide a new means for preparing silver chloride nanoparticles in their free form by thermal treatment.
Źródło:
Acta Physica Polonica A; 2014, 126, 4; 1044-1048
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation and Characterization of d.c.-Plated Nanocrystalline Nickel Deposits
Autorzy:
Szeptycka, B.
Derewnicka, D.
Powiązania:
https://bibliotekanauki.pl/articles/2035480.pdf
Data publikacji:
2002-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
68.37.Lp
68.60.-p
Opis:
The microstructure, microhardness, corrosion, and wear resistance of d.c.-plated Ni electrodeposits prepared from different types of electrolyzing Watts-type baths, without or with organic compounds, ceramic powder - SiC and polymer - polytetrafluoroethylene (PTFE), on Cu substrate, which was subsequently removed from the deposits, were investigated. With the change of the type of bath, the deposit grain size was found to decrease markedly, e.g. deposits with an average grain size of about 50 nm could be produced from a bath containing 45 g/dm$\text{}^{3}$ Ni$\text{}^{2}$+ ions, 5 g/dm$\text{}^{3}$ SiC, and 20 g/dm$\text{}^{3}$ PTFE. The surface morphology on the bath side of the electrodeposited Ni or Ni-SiC-PTFE foils was characteristic of the type of bath, and its roughness correlated well with the observed grain size. Microhardness and wear resistance increased with decreasing grain size, as expected. On discussing the factors controlling deposit grain size, it is concluded that the Ni$\text{}^{2+}$ ion content in the bath and the presence of organic compounds may have a decisive role.
Źródło:
Acta Physica Polonica A; 2002, 102, 2; 199-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
AFM Investigation of Biological Nanostructures
Autorzy:
Strzelecki, J.
Dąbrowski, M.
Strzelecka, J.
Tszydel, M.
Mikulska, K.
Nowak, W.
Balter, A.
Powiązania:
https://bibliotekanauki.pl/articles/1419535.pdf
Data publikacji:
2012-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.64.Dz
81.07.-b
Opis:
Nanostructures created by living organisms, optimized through millions of years of evolution, can be a valuable inspiration for nanotechnology. We employ atomic force microscopy to examine such structures in materials created by common organisms - caddisfly and diatoms. Caddisfly larvae are well known for their ability to spin silk, which serves as an "adhesive tape" to glue various materials and collect food in aqueous environment. Atomic force microscopy imaging of caddisfly silk, performed for the first time by our team, has shown that its surface is patterned with 150 nm extensions - a feature related to its exceptional underwater sticking abilities. Results of force spectroscopy of protein structures found on the surface are also shown. A characteristic feature of diatoms is that they are encased within a unique silica cell wall called frustules, patterned with 200 nm pores, which allow cellular interaction with the environment. We perform atomic force microscopy imaging of frustules in living diatoms as well as adhesion measurements inside pores.
Źródło:
Acta Physica Polonica A; 2012, 122, 2; 329-332
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation and Investigations of $Ni_{0.2}Zn_{0.8}Fe_2O_4$ Ferrite Nanofiber Membranes by Needleless Electrospinning Method
Autorzy:
Streckova, M.
Mudra, E.
Sebek, M.
Sopcak, T.
Dusza, J.
Kovac, J.
Powiązania:
https://bibliotekanauki.pl/articles/1398266.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.Cd
75.50.Gg
81.07.-b
75.47.Lx
Opis:
The preparation of $Ni_{0.2}Zn_{0.8}Fe_2O_4$ nanofiber membranes by simple and versatile needleless electrospinning technique is presented. The single phase of spinel ferrite membrane was obtained after conventional thermal treatment of polyvinyl alcohol (PVA)/metal nitrate precursors at 800°C for 4 h in air. The formation of single-phase fibers was characterized using differential scanning calorimetry accompanied with thermogravimetric analysis. The surface morphology, microstructure and crystal structure were investigated by scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The magnetic properties of the fibrous samples measured in the temperature range from 2 to 300 K verify a soft magnetic behavior, which is quite typical for ferrimagnetic spinel-type ferrites.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 729-731
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Gold Nanolayer Properties Using X-Ray Reflectometry and Spectroscopic Ellipsometry Methods
Autorzy:
Stabrawa, I.
Banaś, D.
Dworecki, K.
Kubala-Kukuś, A.
Braziewicz, J.
Majewska, U.
Wudarczyk-Moćko, J.
Pajek, M.
Góźdź, S.
Powiązania:
https://bibliotekanauki.pl/articles/1398825.pdf
Data publikacji:
2016-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.cm
62.23.St
68.55.-a
81.07.-b
Opis:
X-ray reflectometry and spectroscopic ellipsometry methods were applied for determination of physical properties of gold nonolayers. The nanolayers were prepared by sputtering of gold on different substrates: borosilicate glass, polished crystalline quartz and crystalline silicon. With X-ray reflectometry technique roughness of the substrates and density, thickness and roughness of gold layers were determined. The results showed decrease in density of the gold layers due to their nanometer thickness and that roughness of the underlayer affects roughness of the gold layer. In addition, thicknesses of the gold layers measured with spectroscopic ellipsometry turned out to be in agreement, within the experimental uncertainty, with results of the X-ray reflectometry method.
Źródło:
Acta Physica Polonica A; 2016, 129, 2; 233-236
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

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