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Wyszukujesz frazę "Janik, J." wg kryterium: Autor


Tytuł:
Reflections on the Is: Physics Penetrates Ontology
Autorzy:
Janik, J.
Powiązania:
https://bibliotekanauki.pl/articles/1814013.pdf
Data publikacji:
2007-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Opis:
When considering questions such as What it means that something is? when? where? and how? we may for some purposes say that we are concentrating entirely on is - sometime, somewhere, somehow. This illustrates a transition from physical abstraction to ontological abstraction.
Źródło:
Acta Physica Polonica A; 2007, 112, S; S-189-S-191
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studies of Fractal Aspects of Cement
Autorzy:
Janik, J. A.
Kurdowski, W.
Podsiadły, R.
Samseth, J.
Powiązania:
https://bibliotekanauki.pl/articles/1952755.pdf
Data publikacji:
1996-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.12.Ex
82.70.Gg
Opis:
Small angle neutron scattering can be used to reveal the fractal nature of matter. The problems of fractal aspects of the structure of cement are related to those of fractal aspects of silica aerogels. Natural cement, when mixed with water, transforms after a series of chemical reactions (in a large part) into an amorphous phase called C-S-H. It is believed that the cationic sublattice composed of CaO$\text{}_{6}$ octahedrons constitutes the C-S-H structural basis, to which the SiO$\text{}_{4}$ tetrahedral chains are attached. It is a layer structure in which the cation sublattice determines the way of SiO$\text{}_{4}$ condensation. It is natural to expect that in this way one may obtain a really amorphous substance, since some tetrahedrons may be lacking, which leads to defects. We present here the results of a small angle neutron scattering and X-ray diffraction study of several samples with the pure C-S-H phase for which during the process of chemical synthesis various ratios of molar contents of CaO and SiO$\text{}_{2}$ were used (various C/S ratios). We obtained a gradual change of fractal characteristics with the change of C/S ratio.
Źródło:
Acta Physica Polonica A; 1996, 90, 6; 1179-1184
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fractal Structure of C-S-H and Tobermorite Phases
Autorzy:
Janik, J. A.
Kurdowski, W.
Podsiadły, R.
Samseth, J.
Powiązania:
https://bibliotekanauki.pl/articles/2028897.pdf
Data publikacji:
2001-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.12.Ex
82.70.Gg
Opis:
The C-S-H I phase is the main component of the cement paste, which is a near-amorphous, highly porous gel. Due to high porosity of the sample in this phase we can observe a fractal nature of the volume pores distribution, similar to that observed for silica aerogels. The C-S-H I phase is thermodynamically unstable and crystallize to a tobermorite phase, forming crystal aggregates on the surface of the amorphous paste. The mixture of these two phases, formed in this way, have irregular volume and surface structures, both of which may exhibit the fractal nature. To study the fractal nature of the matter the small angle neutron scattering method is frequently used. We present here the results of small angle neutron scattering studies supported by the X-ray diffraction and scanning electron microscope observations of several samples with the common molar C/S ratio equal to 1. Some of the samples were autoclaved during various time periods to accelerate transformation of the C-S-H I phase to tobermorite. We observed the fractal properties of the volume structure of all samples under study. Moreover, we observed also the fractal behaviors of the surfaces of the samples which were autoclaved.
Źródło:
Acta Physica Polonica A; 2001, 100, 4; 529-537
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fast Stochastic Reorientations in Nematic PAA and PAP
Autorzy:
Podsiadły, R.
Mayer, J.
Janik, J. A.
Krawczyk, J.
Stanek, T.
Powiązania:
https://bibliotekanauki.pl/articles/1963251.pdf
Data publikacji:
1997-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
35.20.Yh
24.50.Fq
61.30.Eb
Opis:
Incoherent quasielastic neutron scattering spectra were measured for nematic para-azoxyanisole (PAA) and para-azoxyphenetole (PAP) with the energy resolution of ca. 30 μ eV, at Dubna IBR-2 reactor. Data processing contained a careful background subtraction and the multiple scattering correction. The corrected spectra were subjected to a reorientational model fitting procedure. For PAA, a model of two convoluted reorientations - that of benzene rings coupled with the terminals and that of the whole molecule around the long molecular axis - gave a fairly good description of the quasielastic neutron scattering spectrum. For PAP, introducing a third motion - interconformational jumps in the ethoxy terminals - in addition to motions suggested for PAA, gave a good agreement with the measured quasielastic neutron scattering spectrum.
Źródło:
Acta Physica Polonica A; 1997, 91, 3; 513-518
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization of GaMnN Ceramics Prepared from Nanopowders by an Anaerobic Synthesis and High-Pressure High-Temperature Sintering
Autorzy:
Gosk, J.
Drygaś, M.
Janik, J.
Gierlotka, S.
Pałosz, B.
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1398535.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Mm
81.07.Wx
81.07.-b
Opis:
Herein, we report a study on magnetic properties of GaMnN ceramics prepared by no additive high-pressure high-temperature sintering of a range of nanopowders, the latter made via an anaerobic synthesis method in the Ga/Mn bimetallic system at various nitridation temperatures and different levels of initial Mn concentration. Measurements of the magnetization as a function of temperature and magnetic field for the ceramics and parent nanopowders showed a typical paramagnetic behavior. Antiferromagnetic interactions between Mn-ions incorporated in the GaN lattice, GaMnN, were revealed and shown to be much stronger in the ceramics than in the respective nanopowders. In addition, in all of these materials an antiferromagnetic contribution originating from a residual Mn₂SiO₄ by-product was also observed. The highest calculated Mn concentration in the nanopowders reached 3.4 at.%. Complex mixtures of gallium nitride polytypes with multimodal particle size distributions in the nanosized range (small nano: 2-8 nm, large nano: 35-60 nm) were converted upon sintering to the single hexagonal GaN phase with average crystallite sizes of 40-80 nm and higher. For the optimal 700°C-treated materials, the Mn concentration in the parent GaMnN nanopowder was 3.2 at.% whereas in the derived ceramics it amounted to 5.5 at.%. At the same time, contributions of the adventitious Mn₂SiO₄ by-product significantly decreased upon sintering.
Źródło:
Acta Physica Polonica A; 2016, 129, 1a; A-103-A-106
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generation and Relaxation of Microstrains in GaN Nanocrystals under Extreme Pressures
Autorzy:
Grzanka, E.
Palosz, B.
Gierlotka, S.
Pielaszek, R.
Bismayer, U.
Janik, J.
Wells, J.
Palosz, F.
Porsch, F.
Powiązania:
https://bibliotekanauki.pl/articles/2035466.pdf
Data publikacji:
2002-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.+w
81.07.Wx
Opis:
Nanocrystalline powders of GaN with grain sizes ranging from 2 to 30 nm were examined under high external pressures by in situ diffraction techniques in a diamond anvil cell at DESY (HASYLAB, Station F3). The experiments on densification of pure powders under high pressure were performed without a pressure medium. The mechanism of generation and relaxation of internal strains and their distribution in nanoparticles was deduced from the Bragg reflections recorded in situ under high pressures at room temperature. The microstrain was calculated from the full-width at half-maximum (FWHM) values of the Bragg lines. It was found that microstrains in GaN crystallites are generated and subsequently relaxed by two mechanisms: generation of stacking faults and change of the size and shape of the grains occurring under external stress.
Źródło:
Acta Physica Polonica A; 2002, 102, 2; 167-174
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Injection of Optically Generated Spins through Magnetic Nonmagnetic Heterointerface: Ruling out Possible Detection Artifacts
Autorzy:
Ghali, M.
Kossut, J.
Janik, E.
Powiązania:
https://bibliotekanauki.pl/articles/2038227.pdf
Data publikacji:
2004-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.-n
73.61.Ga
Opis:
We report on injection of optically created spin-polarized carriers into CdTe-based materials. The injected spins are initially aligned in a diluted magnetic semiconductor CdMnTe layer located on the top of CdMgTe layer in CdMnTe/CdMgTe spintronic generic model structures. A critical discussion of possible artifacts that may complicate the spin detection and its quantitative analysis is given. Although the spin injection efficiency, 80%, has been found by us to be basically independent of the thickness of the spin detecting layer, there is an essential difference between thin and wide detectors related to the strain-induced lifting of the valence band degeneracy in the former, when assessing the efficiency of the spin injection. Most importantly, we observe an effect of switching the spin injection process on and off by an external magnetic field variation within a relatively narrow field range. This effect can be achieved by a careful design of the interface between the diluted magnetic semiconductor and the non-magnetic semiconductor.
Źródło:
Acta Physica Polonica A; 2004, 106, 2; 207-214
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth of Ternary and Quaternary ZnSe Compounds with Transition Metals by Chemical Vapor Transport
Autorzy:
Janik, E.
Grasza, K.
Mycielski, A.
Bąk-Misiuk, J.
Kachniarz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1929755.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.10.Bk
78.55.Et
Opis:
Halogen transport method was applied to grow the crystals of solid solutions of ZnSe and transition metals at the temperature far below the melting point and phase transition temperature. The large crystals of ZnMnSe, ZnFeSe, ZnNiSe and ZnFeSSe were obtained. The technological parameters and shape of the quartz reactor were chosen for growth of a large crystal by self-nucleation; the transparent quartz furnace enabled the control of nucleation by visual observation. The parameters of crystal growth were determined. The crystal quality was estimated by X-ray diffraction method. The composition of crystals was determined by electron microprobe analysis and energy dispersive X-ray fluorescence analysis.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 785-788
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MBE Growth and Characterization of Cubic MnTe(111) on BaF$\text{}_{2}$ Substrates
Autorzy:
Janik, E.
Wojtowicz, T.
Dynowska, E.
Bąk-Misiuk, J.
Domagała, J.
Karczewski, G.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1934056.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
68.55.Bd
68.55.Jk
Opis:
We report on growth by molecular beam epitaxy of cubic MnTe(111) layers on BaF$\text{}_{2}$ (111) substrates. Layers as thick as 0.2-1.0 μm were grown. Basic characterization by X-ray diffraction shows that the cubic crystal structure is deformed to orthorhombic symmetry.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 982-984
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MBE Growth and Magnetooptical Properties of (Zn,Co)Te Layers
Autorzy:
Papaj, M.
Kobak, J.
Rousset, J.
Janik, E.
Golnik, A.
Kossacki, P.
Pacuski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1403629.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.30.Hx
78.20.Ls
71.35.Ji
Opis:
We report on epitaxial growth of diluted magnetic semiconductor (Zn,Co)Te. Reflectivity spectra reveal excitonic transition which split under magnetic field due to giant Zeeman effect. Magnetooptical effects can be described using literature data.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1010-1011
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solid Phase Epitaxy of Ferromagnetic MnAs Layer and Quantum Dots on Annealed GaMnAs
Autorzy:
Sadowski, J.
Kanski, J.
Adell, M.
Domagała, J. Z.
Janik, E.
Łusakowska, E.
Brucas, R.
Hanson, M.
Powiązania:
https://bibliotekanauki.pl/articles/2044534.pdf
Data publikacji:
2005-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.10.Jt
81.15.Hi
68.65.Hb
68.37.Ps
Opis:
We show that post growth annealing of GaMnAs under As capping at temperatures in the range of 180-210ºC leads to significant surface modifications. Depending on GaMnAs layer thickness and composition, we obtain either a smooth continuous reacted (MnAs) surface layer or 3D islands (quantum dots). The surface modifications are due to a solid phase epitaxial process, in which Mn interstitials diffusing to the GaMnAs surface are bound with the As.
Źródło:
Acta Physica Polonica A; 2005, 108, 5; 851-858
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MBE Growth of CdTe/ZnTe Quantum Dots with Single Mn Ions
Autorzy:
Gietka, K.
Kobak, J.
Rousset, J.
Janik, E.
Słupiński, T.
Kossacki, P.
Golnik, A.
Pacuski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1403652.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Et
81.07.Ta
78.67.Hc
75.50.Pp
75.75.Cd
75.30.Hx
Opis:
We report MBE growth and properties of samples with self assembled quantum dots with single manganese ions and low density of quantum dots. Manganese concentration was calibrated using magneto-reflectivity measurements and the giant Zeeman effect in (Cd,Mn)Te and (Zn,Mn)Te layers. Successful incorporation of Mn in the CdTe/ZnTe quantum dots was confirmed using micro-photoluminescence measurements: single manganese ion in quantum dot manifests in sixfold splitting of exciton emission lines due to s, p-d exchange interaction.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1056-1058
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Topographical, Magnetic and Optical Studies of (II,Mn)VI Quantum Structures Grown on (Ga,Mn)As
Autorzy:
Butkutė, R.
Aleszkiewicz, M.
Janik, E.
Cywiński, G.
Wojnar, P.
Däweritz, L.
Primus, J.
De Boeck, J.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/2036853.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Hi
07.79.Pk
78.55.-m
Opis:
We report on an overgrowth of quantum structures consisting of diluted magnetic semiconductor CdMnTe quantum wells with non-magnetic barriers made of CdMgTe or ZnTe on ferromagnetic MnAs and GaMnAs films by molecular beam epitaxy. Atomic force microscopy images of the quantum structures grown on MnAs demonstrated the existence of two types of regions on the surface: protruded islands with micrometric sizes, surrounded by areas of small-scale roughness. Magnetic force microscopy study of these samples revealed a magnetic domain structure only on the above mentioned islands. The (II,Mn)VI quantum wells grown on GaMnAs films exhibited relatively smooth surface, but no magnetic force microscopy signal was measurable either before or after magnetizing the sample. In the luminescence spectra of all our quantum structures the emission attributed to CdMnTe quantum wells was observed. The influence of magnetization on the luminescence line position was investigated.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 649-657
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Type I CdSe and CdMgSe Quantum Wells
Autorzy:
Rudniewski, R.
Rousset, J.
Janik, E.
Kossacki, P.
Golnik, A.
Nawrocki, M.
Pacuski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1376087.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.-e
81.05.Dz
81.07.-b
Opis:
In this work we present the band gap engineering, epitaxial growth and optical characterization of CdSe/$Cd_{0.9}Mg_{0.1}Se$ and $Cd_{0.9}Mg_{0.1}Se$/$Cd_{0.85}Mg_{0.15}Se$ quantum wells with a thickness ranging from 1 to 15 nm. These structures exhibit strong near-band-gap photoluminescence from helium up to room temperature. The emission energy is tuned in the range from 1.74 to 2.1 eV at 7 K, depending on the thickness and well composition. The most intense photoluminescence (both at 7 and 300 K) was observed for 10 nm thick CdSe/$Cd_{0.9}Mg_{0.1}Se$ wells. Such a structure gives also a sharp emission line (FWHM = 20 meV) at low temperature. The presented quantum wells are well suited for being embedded in lattice matched ZnTe based microcavities.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1167-1170
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Characterization of MBE-Grown Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te Layers by Raman Spectroscopy
Autorzy:
Szuszkiewicz, W.
Dynowska, E.
Janik, E.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Jouanne, M.
Powiązania:
https://bibliotekanauki.pl/articles/1945228.pdf
Data publikacji:
1996-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.-e
75.50.Pp
78.30.-j
Opis:
In this paper we discuss a possibility of an optical characterization of thin semiconductor epilayers by Raman scattering measurements. As an example zinc blende Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te epilayers (0.66 ≤ x ≤ 1.0) have been grown by molecular beam epitaxy method and investigated by Raman scattering and X-ray diffraction. Information resulting from both methods is compared and discussed.
Źródło:
Acta Physica Polonica A; 1996, 89, 3; 335-340
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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