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Wyszukujesz frazę "61.72.J-" wg kryterium: Temat


Tytuł:
A Study of Point Defects in the B2-Phase Region of the Fe-Al System by Mössbauer Spectroscopy
Autorzy:
Hanc, A.
Kansy, J.
Dercz, G.
Pająk, L.
Oleszak, D.
Mrzigod, J.
Powiązania:
https://bibliotekanauki.pl/articles/1811589.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Bb
61.72.J-
76.80.+y
Opis:
In this work, we employed the Mössbauer spectroscopy and X-ray powder diffraction in a study of point defect formation in intermetallic phases of the B2 structure of the Fe-Al system as a function of Al concentration. The results are compared with the concentrations of point defect determined from positron annihilation data. In the Mössbauer effect, two types of samples are investigated: Fe-Al alloys with few additives obtained by induction melting and Al-rich metallic powders produced by the self-decomposition method and intensive grinding of high energy in the electro-magneto-mechanical mill. We present the values of the $\text{}^{57}Fe$ isomer shift and quadrupole splitting for the components describing the point defect in the local environment of a Mössbauer nuclide. The concentration of the Fe vacancies and Fe atoms substituting Al (Fe-AS) are determined. The results showed that an increase in Al content causes an increase in vacancy and Fe-AS concentration.
Źródło:
Acta Physica Polonica A; 2008, 114, 6; 1555-1562
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acousto-electric interaction in magnetised piezoelectric semiconductor quantum plasma
Autorzy:
Ghosh, S.
Muley, A.
Powiązania:
https://bibliotekanauki.pl/articles/1058496.pdf
Data publikacji:
2016-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.50.+b
52.35.-g
61.72.uj
77.65.-j
Opis:
Amplification of an acoustic wave is considered in magnetised piezoelectric n-type semiconductor plasma under quantum hydrodynamic regime. The important ingredients of this study are the inclusion of quantum diffraction effect via the Bohm potential, statistical degeneracy pressure, and externally applied magnetostatic field in the momentum balance equation of the charged carriers. A modified dispersion relation is derived for evolution of acoustic wave by employing the linearization technique. Detailed analysis of quantum modified dispersion relation of acoustic wave is presented. For a typical parameter range, relevant to n-InSb at 77 K, it is found that the non-dimensional quantum parameter H reduces the gain while magnetic field enhances the gain of acoustic wave. The crossover from attenuation to amplification occurs at (ϑ₀/ϑₛ)=1 and this crossover point is found to be unaffected by quantum correction and magnetic field. It is also found that the maximum gain point shifts towards lower drift velocity regime due to the presence of magnetic field while quantum parameter H shifts this point towards higher drift velocity. Numerical results on the acoustic gain per radian and acoustic gain per unit length are also illustrated. Our results could be useful in understanding acoustic wave propagation in magnetised piezoelectric semiconductor in quantum regime.
Źródło:
Acta Physica Polonica A; 2016, 130, 6; 1401-1405
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of CMSX-4 single-crystalline turbine blades root by electron and X-ray diffraction methods
Autorzy:
Krawczyk, J.
Zubko, M.
Bogdanowicz, W.
Tondos, A.
Sieniawski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1058074.pdf
Data publikacji:
2016-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.10.Aj
61.72.Ff
61.05.J-
Opis:
The root of single-crystalline turbine blade made of CMSX-4 superalloy were studied. The studied blade was produced by the Bridgman technique in industrial ALD furnace at withdrawal rate of 3 mm/min. The samples for investigations were cut from the blade root parallel to the withdrawal direction. Metallographic sections of longitudinal samples planes were prepared for further investigations. The samples were analysed using scanning electron microscopy and the Laue diffraction studies. The crystal orientations in macro-scale were determined by analysis of the Laue pattern and local crystal orientations were studied by electron backscattered diffraction technique. Morphology of dendrites were examined by analysis of scanning electron microscopy macro-images. Study of subgrain structure was performed by X-ray diffraction topography. The sharp parallel contrast bands, visible on the X-ray topograms, were related with dendrite cores, arranged with the same direction. Additionally, the low angle boundaries were formed in certain samples, visible on the topograms as contrast shifts. Step changes of local crystal orientation in certain areas were observed on the electron backscattered diffraction maps. The electron backscattered diffraction crystal orientation maps were related to the misorientation visualized in topograms.
Źródło:
Acta Physica Polonica A; 2016, 130, 4; 1104-1106
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anharmonicity Effects in Nanocrystals Studied by Raman Scattering Spectroscopy
Autorzy:
Dohčević-Mitrović, Z.
Popović, Z.
Šćepanović, M.
Powiązania:
https://bibliotekanauki.pl/articles/1807800.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.22.-m
78.67.Bf
78.30.-j
61.72.uj
Opis:
Phonon-phonon interactions were investigated in various nanocrystalline powders like anatase $TiO_{2-δ}$, pure $CeO_{2-δ}$ and ceria doped with Nd(Gd) analyzing temperature dependent Raman spectra of these systems. Phonon confinement model based on size, inhomogeneous strain and anharmonic effects was used to properly describe the evident changes present in the Raman spectra of pure and doped ceria nanocrystalline samples. In small particles of pure and doped ceria nanocrystals, when size effects have minor impact on Raman modes, four phonon anharmonic processes prevail under the three-phonon ones. When nanopowdered particles are grown enough size effects provoke changes of the anharmonic interactions when three-phonon coupling prevails over the four-phonon anharmonic processes. In nanocrystalline anatase $TiO_2$ evident blueshift of the most prominent $E_g$ Raman mode probably originates from dominant four-phonon anharmonic interactions.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 36-41
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anomalous Hall Effect in $Ge_{1-x-y}Pb_{x}Mn_{y}Te$ Composite System
Autorzy:
Podgórni, A.
Kilanski, L.
Dobrowolski, W.
Górska, M.
Domukhovski, V.
Brodowska, B.
Reszka, A.
Kowalski, B.
Slynko, V.
Slynko, E.
Powiązania:
https://bibliotekanauki.pl/articles/1376191.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.J-
72.80.Ga
75.40.Mg
75.50.Pp
Opis:
The purpose of this study was to investigate the magnetotransport properties of the $Ge_{0.743}Pb_{0.183}Mn_{0.074}Te$ mixed crystal. The results of magnetization measurements indicated that the compound is a spin-glass-like diluted magnetic semiconductor with critical temperature $T_{SG}$=97.5 K. Nanoclusters in the sample are observed. Both, matrix and clusters are magnetically active. Resistivity as a function of temperature has a minimum at 30 K. Below the minimum a variable-range hopping is observed, while above the minimum a metallic-like behavior occurs. The crystal has high hole concentration, p=6.6×$10^{20}$ $cm^{-3}$, temperature-independent. Magnetoresistance amplitude changes from -0.78 to 1.18% with increase of temperature. In the magnetotransport measurements we observed the anomalous Hall effect with hysteresis loops. Calculated anomalous Hall effect coefficient, $R_{S}$ = 2.0×$10^{6}$ $m^{3}$/C, is temperature independent. The analysis indicates the extrinsic skew scattering mechanism to be the main physical mechanism responsible for anomalous Hall effect in $Ge_{0.743}Pb_{0.183}Mn_{0.074}Te$ alloy.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1180-1183
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Channeling Study of Co and Mn Implanted and Thermally Annealed Wide Band-Gap Semiconducting Compounds
Autorzy:
Ratajczak, R.
Werner, Z.
Barlak, M.
Pochrybniak, C.
Stonert, A.
Zhao, Q.
Powiązania:
https://bibliotekanauki.pl/articles/1402209.pdf
Data publikacji:
2015-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.-j
61.72.-y
81.05.-t
82.80.-d
85.40.-e
Opis:
The defect build-up, structure recovery and lattice location of transition metals in ion bombarded and thermally annealed ZnO and GaN single crystals were studied by channeled Rutherford backscattering spectrometry and channeled particle-induced X-ray emission measurements using 1.57 MeV ⁴He ions. Ion implantation to a fluence of 1.2×10¹⁶ ions/cm² was performed using 120 keV Co and 120 keV Mn ions. Thermal annealing was performed at 800°C in argon flow. Damage distributions were determined using the Monte Carlo McChasy simulation code. The simulations of channeled Rutherford backscattering spectra reveal that the ion implantation leads to formation of two types of defect structures in ZnO and GaN such as point and extended defects, such as dislocations. The concentrations of both types of defects are at a comparable level in both structures and for both implanted ions. Differences between both implantations appear after thermal annealing where the Mn-doped ZnO reveals much better transition metals substitution and recovery effect.
Źródło:
Acta Physica Polonica A; 2015, 128, 5; 845-848
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of Materials by Raman Scattering
Autorzy:
Kozielski, M.
Powiązania:
https://bibliotekanauki.pl/articles/2047294.pdf
Data publikacji:
2007-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
62.20.-x
61.72.-y
36.20.Ng
Opis:
The paper reports on the use of phonon spectra obtained with the Raman spectroscopy for characterization of different materials. The Raman scattering spectra obtained for zinc selenide crystals, mixed crystals zinc selenide admixtured with magnesium or beryllium, oxide crystals including strontium lanthanum gallate, molecular crystals of triammonium hydrogen diseleniate and a homologous series of polyoxyethylene glycols are analysed.
Źródło:
Acta Physica Polonica A; 2007, 111, 3; 343-360
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Grain Boundary Structure in Metals and Semiconductors as Probed by Positrons
Autorzy:
Kuriplach, J.
Powiązania:
https://bibliotekanauki.pl/articles/1196087.pdf
Data publikacji:
2014-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.60.+z
61.72.Mm
61.72.J-
78.70.Bj
Opis:
Vacancy behavior and positron trapping at selected grain boundaries in iron, nickel, and zirconia are investigated theoretically. It is found that the grain boundary vacancy loses its free volume in metals at moderate temperatures whereas it is kept up to very high temperatures in zirconia. The consequences of these findings for positron annihilation studies of nanocrystalline materials are discussed.
Źródło:
Acta Physica Polonica A; 2014, 125, 3; 722-725
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Defect Transformations in Ion Bombarded InGaAsP
Autorzy:
Ratajczak, R.
Turos, A.
Stonert, A.
Nowicki, L.
Strupiński, W.
Powiązania:
https://bibliotekanauki.pl/articles/1504046.pdf
Data publikacji:
2011-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.-j
61.72.-y
81.05.-t
82.80.-d
85.40.-e
Opis:
Damage buildup and defect transformations at temperatures ranging from 15 K to 300 K in ion bombarded InGaAsP epitaxial layers on InP were studied by in situ Rutherford backscattering/channeling measurements using 1.4 MeV $\text{}^4He$ ions. Ion bombardment was performed using 150 keV N ions and 580 keV As ions to fluences ranging from 5 × $10^{12}$ to 6 × $10^{14}$ at./$cm^2$. Damage distributions were determined using the McChasy Monte Carlo simulation code assuming that they consist of randomly displaced lattice atoms and extended defects producing bending of atomic planes. Steep damage buildup up to amorphisation with increasing ion fluence was observed. Defect production rate increases with the ion mass and decreases with the implantation temperature. Parameters of damage buildup were evaluated in the frame of the multi-step damage accumulation model. Following ion bombardment at 15 K defect transformations upon warming up to 300 K have also been studied. Defect migration beginning above 100 K was revealed leading to a broad defect recovery stage with the activation energy of 0.1 eV for randomly displaced atoms and 0.15 eV for bent channels defects.
Źródło:
Acta Physica Polonica A; 2011, 120, 1; 136-139
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Defects Studies of ZnO Single Crystals Prepared by Various Techniques
Autorzy:
Lukáč, F.
Čížek, J.
Procházka, I.
Melikhova, O.
Anwand, W.
Brauer, G.
Powiązania:
https://bibliotekanauki.pl/articles/1196118.pdf
Data publikacji:
2014-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
61.72.J-
Opis:
The aim of the present work was a comparison of defects in ZnO crystals grown by various techniques available nowadays, namely hydrothermal growth, pressurized melt, Bridgman method growth and vapor phase growth. Positron annihilation spectroscopy was employed as a principal tool for characterization of defects in ZnO crystals grown by above mentioned various techniques. ZnO crystals can be divided into two groups: (i) hydrothermal grown crystals, which exhibit positron lifetime of 179-182 ps and (ii) ZnO crystals grown by the other techniques (pressurized melt, Bridgman method, vapor phase growth) which are characterized by the lower lifetimes falling in the range of 160-173 ps. Comparison of experimental data with ab initio theoretical calculations revealed that HT grown ZnO crystals contains Zn vacancies associated with hydrogen atom in a bond-centered site. On the other hand, ZnO crystals prepared by other techniques contain most probably stacking faults created by stresses induced by temperature gradients in the melt.
Źródło:
Acta Physica Polonica A; 2014, 125, 3; 748-751
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Depth Profiling of Defects in He Implanted $SiO_2$
Autorzy:
Mariazzi, S.
Toniutti, L.
Brusa, R.
Duarte Naia, M.
Karbowski, A.
Karwasz, G.
Powiązania:
https://bibliotekanauki.pl/articles/1812538.pdf
Data publikacji:
2008-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.60.+z
78.70.Bj
68.55.-a
61.82.Ms
61.72.J-
Opis:
Thin layer of $SiO_2$ thermally grown on p-type Si was implanted with $He^+$ ions at 30 keV with a dose of $5×10^{15}$ ions/$cm^2$. $SiO_2//Si$ samples were depth profiled by Doppler broadening positron annihilation spectroscopy to identify induced defects in the silicon oxide, at the interface and in the Si substrate. In one sample the silicon dioxide layer was removed by etching after implantation. It is shown that removing the silicon dioxide layer some more information about defects into the substrate can be found.
Źródło:
Acta Physica Polonica A; 2008, 113, 5; 1447-1453
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of $Fe^{2+} (Fe^{3+})$ Doping on Structural Properties οf $CeO_2$ Nanocrystals
Autorzy:
Radović, M.
Dohčević-Mitrović, Z.
Paunović, N.
Šćepanović, M.
Matović, B.
Popović, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1807838.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.uj
78.30.-j
75.50.Tt
Opis:
We have measured the Raman scattering and magnetization of pure and $Fe^{2+}(Fe^{3+})$ doped $CeO_2$ nanopowders at room temperature. The Raman scattering spectra revealed the existence of $CeO_2$ fluorite cubic structure for all investigated samples. The Raman active mode at about 600 $cm^{-1}$, seen in all samples, can be ascribed to the $CeO_2$ intrinsic oxygen vacancies. Additional Raman modes at 720 $cm^{-1}$, 1320 $cm^{-1}$ and 1600 $cm^{-1}$, which appear in the spectra of doped samples, can be assigned to maghemite $(γ-Fe_2O_3)$ cation deficient structure, to $2ω_{LO}$ IR-allowed overtone and two magnon structure, respectively. This implies that our powders are composed of mixed valence states and have defective structure. Presence of oxygen defect states and magnetic ions can be responsible for the observed ferromagnetism at room temperature in both pure and Fe doped samples.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 84-87
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Investigations of Electrons and Neutrons Irradiated Cubic Boron Nitride
Autorzy:
Azarko, I.
Ignatenko, O.
Karpovich, I.
Odzhaev, V.
Kozlova, E.
Zhukowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/1400479.pdf
Data publikacji:
2013-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
81.05.Ea
61.72.J-
Opis:
Microcrystals of cubic boron nitride powders synthesised under different conditions and further irradiated with neutrons and electrons have been investigated. It was found that some changes of the samples' paramagnetic properties depend on the electron irradiation dose. It was also shown that the initial boron type defects growth occurs under thermal neutron, as well as under fast neutrons irradiation. The nitrogen-containing defects concentration changes in a threshold manner.
Źródło:
Acta Physica Polonica A; 2013, 123, 5; 923-925
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Grain-Subgrain Structure and Vacancy-Type Defects in Submicrocrystalline Nickel at Low Temperature Annealing
Autorzy:
Kuznetsov, P.
Lider, A.
Bordulev, Yu.
Laptev, R.
Rakhmatulina, T.
Korznikov, A.
Powiązania:
https://bibliotekanauki.pl/articles/1402134.pdf
Data publikacji:
2015-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.37.Ef
61.72.J-
61.72.Lk
61.72.-y
81.40.Ef
78.70.Bj
Opis:
Scanning tunneling microscopy, positron annihilation and X-ray diffraction were applied for the study of annealing of submicrocrystalline nickel prepared by equal channel angular pressing. Several processes were revealed in the structure of submicrocrystalline nickel on different scale levels during annealing in the range Δ T=(20÷360)°C. A decrease of grain nonequiaxiality and further structure refinement were observed with a temperature increase in the range Δ T=(20÷180)°C. Subgrain growth with maximum =60 nm at 120°C occurred on the lower scale level within the same temperature range. Grain growth and microstress decrease in submicrocrystalline nickel observed at T>180°C indicate the beginning of recrystallization. The main positron trap centers were identified in submicrocrystalline nickel within different temperature ranges. In as-prepared samples positrons are trapped at dislocation-type defects and vacancy clusters that can include up to 5 vacancies. At the annealing temperature Δ T=(20÷180)°C positrons are trapped at low-angle boundaries enriched by impurities. Within the range Δ T=(180÷360)°C the dominant trap is dislocations.
Źródło:
Acta Physica Polonica A; 2015, 128, 4; 714-717
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Induced Absorption in Gadolinium Gallium Garnet Irradiated by High Energy $\text{}^{235}U$ Ions
Autorzy:
Potera, P.
Ubizskii, S.
Sugak, D.
Schwartz, K.
Powiązania:
https://bibliotekanauki.pl/articles/1550538.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.jn
81.40.Wx
61.80.Ba
61.80.Jh
61.72.J-
Opis:
The present work is devoted to investigation of optical absorption in pure $Gd_{3}Ga_{5}O_{12}$ (GGG) single crystals in the spectral range 0.2-1.1 μm induced under influence of the $\text{}^{235}U$ ions irradiation with energy 2640 MeV and a fluence $10^{9}-10^{11} cm^{-2}$. The induced absorption for $10^{9} cm^{-2}$ is caused by recharging of point defects, both growth ones and impurities. After irradiation by $\text{}^{235}U$ ions with fluences starting from $3 \times 10^{9} cm^{-2}$ the absorption rise is probably caused by contribution of the lattice destroying as a result of heavy ion bombardment as well as radiation displacement defects.
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 181-183
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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