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Tytuł:
Low-Symmetry Aspects in EPR Spectra of Mn$\text{}^{2+}$ at Bi$\text{}^{3+}$ Sites in BiVO$\text{}_{4}$ Single Crystal
Autorzy:
Yeom, T. H.
Choh, S. H.
Rudowicz, Cz.
Powiązania:
https://bibliotekanauki.pl/articles/1920948.pdf
Data publikacji:
1992-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
76.30.Da
61.16.Hn
78.20.Hp
Opis:
Zero-field splitting parameters obtained from EPR X-band experiments of Baran et al. (1985) and Yeom et al. (1992) are reanalyzed. Transformation relations are derived to express the two sets of data in the same axis system. Problems arising from using a truncated zero-field splitting Hamiltonian in fitting the experimental data are elucidated. Low-symmetry aspects in EPR spectra of Mn$\text{}^{2+}$ at Bi$\text{}^{3+}$ sites in BiVO$\text{}_{4}$ single crystal are considered. Good agreement for orthorhombic parameters b$\text{}_{2}^{0}$ and b$\text{}_{2}^{2}$ is obtained indicating that the centres observed in the two cases are the same Mn centres. The remaining b$\text{}_{k}^{q}$ parameters accounting for the actual site symmetry around Mn$\text{}^{2+}$ impurity which seems to be lower than orthorhombic in the ferroelastic phase cannot be unambiguously determined from the existing EPR data.
Źródło:
Acta Physica Polonica A; 1992, 82, 3; 503-510
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Strain in II-VI Semiconductor Superlattices Using Electron Paramagnetic Resonance of Mn$\text{}^{++}$
Autorzy:
Furdyna, J. K.
Qazzaz, M.
Yang, G.
Montes, L.
Xin, S. H.
Luo, H.
Powiązania:
https://bibliotekanauki.pl/articles/1933687.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.-w
71.55.Gs
Opis:
We explore the possibility of using electron paramagnetic resonance (EPR) of Mn$\text{}^{++}$ for measuring uniaxial strain in II-VI superlattices. This work is motivated by the fact that the EPR spectrum of Mn$\text{}^{++}$ is very strongly affected by crystalline fields. Changes in a crystalline field which arise from strain are thus automatically expected to have a profound effect on the EPR spectrum. Consistent with this expectation, we have observed giant crystal field splittings of Mn$\text{}^{++}$ EPR lines in ZnTe/MnTe, CdTe/MnTe, and ZnTe/MnSe superlattices. The EPR spectra observed in these systems are ascribed to isolated Mn$\text{}^{++}$ ions diffused into the ZnTe or the CdTe layers from the respective MnTe or MnSe layers. In addition to providing precise information oii the magnitude and the sign of strain produced by lattice mismatch between the superlattice constituents, we show that the EPR spectrum also provides a direct measure of strain fluctuations in the layered medium.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 607-618
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrical and Optical Studies in Ge$\text{}_{100-x}$S$\text{}_{x}$ Chalcogenide Thin Films
Autorzy:
Metwally, H. S.
Powiązania:
https://bibliotekanauki.pl/articles/2027396.pdf
Data publikacji:
2001-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Jc
78.66.Jg
Opis:
Thin films of Ge$\text{}_{100-x}$S$\text{}_{x}$ with different values of x are deposited on quartz substrates by a conventional thermal evaporation technique. The electrical conductivity of these films was measured. The experiments reveal that the electronic conduction is strongly composition dependent and is thermally activated with a single activation energy for x>40. A variable range hopping conduction mechanism seems to dominate when x=16 and 27. The optical absorption of the films is investigated using spectrophotometric measurements of the transmittance and reflectance in the wavelength range 200-3000 nm. All the studied compositions obey the Tauc relation concerning the non-direct transitions. The optical energy gap E$\text{}_{g}$ value increases with the increase in chalcogen content x. The Urbach parameter E$\text{}_{0}$ decreases from 310 meV to 149 meV as x increases from 16 to 70.
Źródło:
Acta Physica Polonica A; 2001, 99, 6; 683-690
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
DLC Coatings by $PI^{3}D:$ Low-Voltage žersus High-Voltage Biasing
Autorzy:
Ryoo, H.
Nikiforov, S.
Rim, G.
Shenderey, S.
Oh, H.
Chung, S.
Powiązania:
https://bibliotekanauki.pl/articles/1807961.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.77.Dq
68.35.Gy
68.55.-a
78.30.-j
Opis:
Diamond-like carbon (DLC), in particular hydrogenated amorphous carbon (a-C:H) films have been formed on various conductive and dielectric materials by plasma immersion ion implantation and deposition $(PI^{3}D)$ processing. Effect of pulse voltage and other process parameters on the film properties was investigated. It was found that for conductive substrates, a low-voltage ( ≈1 kV), high repetition rate pulsing provides better overall film performance comparing to that obtained by applying higher voltages, which is also favourable for conformal treatment of 3D workpieces. However, short 1-2 μs, high-voltage 5-20 kV pulses are required for dielectric workpieces several millimeter thick. Good film adhesion was achieved by forming a Si-containing buffer layer using hexamethyldisiloxane (HMDSO) as a precursor and a low-voltage pulsing. Roughness and wettability of DLC coatings was found to be controlled by varying the bias specs and sample temperature. Very smooth films with average roughness less than 1 Å were prepared at optimised process parameters.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 1146-1148
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Ion-Channel Guiding on the Chaotic Electron Trajectories in a Free Electron Laser
Autorzy:
Saviz, S.
Mehdian, H.
Powiązania:
https://bibliotekanauki.pl/articles/2043369.pdf
Data publikacji:
2005-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.60.Cr
Opis:
It has been confirmed that when the equilibrium self-fields were taken into account, the motion of an electron in a helical wiggler with axial magnetic field may be chaotic. In this paper, the effect of an ion-channel guiding on the chaotic electron trajectories is analyzed. It is shown that the ion-channel guiding may modify the chaotic electron trajectories. It is also found that when the parameter ε, i.e. ε=ω$\text{}_{pb}^{2}$/4ω$\text{}_{c}^{2}$, is increased, the density of the ion-channel guiding, i.e. α$\text{}_{i}$=ω$\text{}_{pi}^{2}$/4ω$\text{}_{c}^{2}$, must be increased to keep the modification of the chaotic motion. The chaotic trajectories for constant parameter ε and increased density of the ion-channel guiding are presented. Numerical calculations are used to find the intersection between steady state group I and group II and resonance curves. Poincaré surface-of-section maps are generated to demonstrate the chaotic electron trajectories with axial magnetic field and its modification in the presence of an ion-channel guiding.
Źródło:
Acta Physica Polonica A; 2005, 107, 6; 895-906
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Manipulation of ZnO/Polymer Nanocomposites Generated by Nanosecond Laser Ablation in Organic Liquid
Autorzy:
Faramarzi, S.
Bajelan, S.
Akbarian, H.
Powiązania:
https://bibliotekanauki.pl/articles/1400413.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.35.Np
79.20.Eb
78.67.Bf
07.60.Rd
Opis:
We present experimental results on the production of ZnO nanoparticles with second harmonic of pulsed nanosecond Nd:YAG laser (λ=532 nm, pulse duration=5 ns) in tetrahydrofuran with 0.0 wt% and 0.8 wt% concentrations of polystyrene by high (200 mJ pulse energy) and moderate (80 mJ pulse energy) pulse energies. The produced colloids were characterized by ultraviolet-visible absorption, transmission electron microscopy, room temperature photoluminescence emission and dynamic light scattering. The mean size of nanoparticles decreased from 40 nm to 22 nm by adding polymer (0.8 wt%) and increasing the pulse energy. The colloidal nanocomposites showed a shoulder at 360 nm in ultraviolet-visible absorption spectra and were found very stable for one month. We observed two photoluminescence emission peaks in UV region at 380 nm and 400 nm attributed to exciton transition. Dynamic light scattering indicated that the size and aggregation of nanocomposites were controlled by polymer concentration and pulse energy.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 152-155
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Implementation on Visualization of Some Complex Physics Problems Embodied in Difficulty with Interactive Materials for Undergraduates
Autorzy:
Aydin, S.
Genç, H.
Powiązania:
https://bibliotekanauki.pl/articles/1033356.pdf
Data publikacji:
2017-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.70.-c
85.30.-z
85.30.De
Opis:
Physical phenomena and the nature of materials require both qualitative and quantitative research to be understood thoroughly. This process often necessitates the use of complicated and expensive equipments. Also in electrical-electronics discipline, especially the nature of semiconductor materials and the behavior of them have a special place. In engineering education, it is often more important for undergraduates to understand the behavior of material and the results of that at the basic level. For this purpose it is sufficient to analyze semiconductor materials with interactive software unlike physics scholars who apply mostly physically to analyze. Understanding the physical properties of applied materials and digitalizing the characteristics of these materials by coding in programming environment maintain its importance. In this context, designing of interactive programs to analyze physical phenomena in electrical-electronics engineering without the need for licensed software has been presented. For this purpose, some semiconductor phenomena involved with electronics engineering have been selected as a pilot and web based 3D Java graphic AWT applications have been designed.
Źródło:
Acta Physica Polonica A; 2017, 131, 1; 74-77
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Usage of Perlitic Pumice from İzmir-Menderes (Turkey) in the Production of Low-Strength Lightweight Concrete
Autorzy:
Ceylan, H.
Saraç, S.
Powiązania:
https://bibliotekanauki.pl/articles/1031438.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Rm
81.05.-t
Opis:
Lightweight aggregates, used to produce cavity blocks in the construction sector, vary according to their technical properties and thus, technical analyses should be performed on lightweight aggregate specimens. Lightweight aggregates, like pumice, are widely employed for the production of construction elements, used as light masonry units. In literature there are studies related to applications of various lightweight aggregates, such as volcanic slag, ignimbrite and expanded clay, in addition to pumice, to produce porous cavity blocks. This study investigates the usability of perlitic pumice formations, present around Menderes, İzmir (Turkey), as lightweight aggregate. Many experiments were conducted to investigate this possibility and to determine the optimum mixing ratios of aggregate. Based on the results, for 10% of cement by volume, the optimum aggregate mixing ratio was 40% 0-4 mm and 60% 4-8 mm.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 667-669
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation and Characterization of $Co-Mo//γ-Al_2O_3,$ $Ni-Mo/γ-Al_2O_3$ and $(Co/Ni)-Mo/γ-Al_2O_3$ Metal Oxides by Sol-Gel Process
Autorzy:
Figen, H.
Baykara, S.
Powiązania:
https://bibliotekanauki.pl/articles/1491358.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Fw
81.70.-q
Opis:
In this study, $Co-Mo//γ-Al_2O_3,$ $Ni-Mo//γ-Al_2O_3$ and $(Co/Ni)-Mo/γ-Al_2O_3$ metal oxides have been prepared by the sol-gel process using citric acid and calcined at 800C for 5 h. Phases of synthesized materials were characterized with X-ray diffraction. Morphological analysis and elemental composition of oxides were determined by scanning electron microscope and energy dispersion spectroscopy. Surface analyses of the metal oxides have been studied using the Brunner-Emmett-Teller surface analyzer. Effects of substitution of cobalt and nickel together on the physical properties of the synthesized oxides were also investigated.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 224-226
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Optical Characterization of GaN/AlGaN Single Quantum Disk Nanorods
Autorzy:
Almokhtar, M.
Emura, S.
Tambo, H.
Hasegawa, S.
Asahi, H.
Powiązania:
https://bibliotekanauki.pl/articles/1400040.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Km
78.67.De
81.07.Vb
Opis:
GaN/AlGaN single quantum disks on GaN nanorods were grown on Si (001) substrate with native $SiO_2$ layer by a plasma-assisted molecular-beam epitaxy under nitrogen-rich conditions. The transmission electron microscopy observations show single GaN nanorods images with an average thickness of 4 nm for the GaN single quantum disk and nanorod diameter of 15 nm. The observed photoluminescence spectra at 8 K show a peak at 3.475 eV, attributed to an exciton recombination in GaN. A strong peak was observed at 3.542 eV. This peak is attributed to the quantum confinement of excitons in the GaN quantum disks.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 473-475
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis of SiO₂ Nanostructures Using Sol-Gel Method
Autorzy:
Azlina, H.
Hasnidawani, J.
Norita, H.
Surip, S.
Powiązania:
https://bibliotekanauki.pl/articles/1398797.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20-n
Opis:
Sol-gel method is the simplest method and has the ability to control the particle size and morphology through systematic monitoring of reaction parameters. The objective of this research is to synthesize silica nanostructures by sol-gel method and to characterize the synthesized silica nanostructures. Silica nanoparticles were synthesized via the sol-gel method using Tetraethyl orthosilicate as a precursor. The acetic acid and distilled water were used as the catalyst and the hydrolyzing agent. Varied parameters of the study were the aging time in the range of 2 to 6 h and the calcination temperature in the range of 600-700°C. The obtained silica nanopowder was characterized using FESEM, and Nano-Particle Size Analyzer. The results show that the silica nanospheres were successfully synthesized by using sol-gel method with the optimum parameters of 700°C of calcination temperature and 2 h of aging time. The average size of silica nanoparticles was in the range of 79.68 nm to 87.35 nm.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 842-844
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Self-Tuning Proportional Integral Derivative pH Control: Application to a Bioprocess
Autorzy:
Altuntaş, S.
Hapoğlu, H.
Ertunç, S.
Alpbaz, M.
Powiązania:
https://bibliotekanauki.pl/articles/1031479.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
Experimental self-tuning proportional-integral-derivative application
pH control
kefir yeast
cheese whey
Opis:
pH control has received considerable attention in preparation of cheese whey drink, by fermentation with kefir yeast, because of its critical role in quality assurance. To improve the rheological and sensory properties of this drink, milk and grape juice are added to the bioprocess medium. Cheese whey drink was produced from the pasteurized mixture, which contains cheese whey, glucose, grape juice and milk. The fermentation of this mixture with kefir yeast in a batch bioreactor was investigated. The pH was monitored during the production of cheese whey drink. Experiments show that kefir yeast is very resistant to contamination. A self-tuning proportional-integral-derivative control was applied to the bioprocess. The software of controller was developed by using the autoregressive moving average exogenous model. The model parameters were evaluated from input-output data by using a pseudo random binary sequence. The experimental results illustrate that the controller can maintain the pH at the desired value. It is noted that the self-tuning proportional-integral-derivative pH control results with the best controller tuning parameters and provides very good results, compared to initially adjusted case, without control. The best tuning parameters were found as t₁=0.1, t₂=0, t₃=0, by comparing experimental application results.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 1006-1009
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Semi-Relativistic Scattering States of the Hulthén and Hyperbolic-Type Potentials
Autorzy:
Hassanabadi, H.
Yazarloo, B.
Hassanabadi, S.
Zarrinkamar, S.
Powiązania:
https://bibliotekanauki.pl/articles/1399494.pdf
Data publikacji:
2013-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.65.Pm
03.65.Nk
Opis:
In this paper, the scattering states of the spinless-Salpeter equation are investigated for Hulthén and hyperbolic-type potentials for any arbitrary l-state. Approximate analytical formulae of the wave functions and the scattering phase shifts are reported.
Źródło:
Acta Physica Polonica A; 2013, 124, 1; 20-22
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behaviors of Phase Diagrams of Ising Model with Competing Ternary and Binary Interactions on a Cayley Tree of Arbitrary Order
Autorzy:
Akin, H.
Ganikhodjaev, N.
Uguz, S.
Temir, S.
Powiązania:
https://bibliotekanauki.pl/articles/1490877.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.-i
64.60.De
Opis:
An Ising model with competing interactions has recently been studied extensively because of the appearance of nontrivial magnetic orderings. In this paper, we study the phase diagrams for the Ising model on a Cayley tree with competing nearest-neighbor interactions J and ternary prolonged interactions $J_{t_{p}}$ on a Cayley tree of arbitrary order k and compare with the phase diagrams obtained in Uguz et al. and Vannimenus results for the Ising model on a Cayley tree with competing nearest-neighbor interactions J and ternary prolonged interactions $J_{p}$. For some values of k, we obtain phase diagrams of the model. We clarify the role of order k of the Cayley tree. We also plot the variation of the wave vector with temperature.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 104-107
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Competing Interactions on a Cayley Tree-Like Lattice: Pentagonal Chandelier
Autorzy:
Uguz, S.
Ganikhodjaev, N.
Akin, H.
Temir, S.
Powiązania:
https://bibliotekanauki.pl/articles/1490904.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.-i
64.60.De
Opis:
Different types of lattice spin systems with competing interactions have rich and interesting phase diagrams. In this study we present some new results for such systems involving the Ising spin system (i.e. σ = ± 1) using a generalization of the Cayley tree-like lattice approximation. We study the phase diagrams for the Ising model on a Cayley tree-like lattice, a new lattice type called pentagonal chandelier, with competing nearest-neighbor interactions $J_1$, prolonged next-nearest-neighbor interactions $J_{p}$ and one-level next-nearest-neighbor senary interactions $J_{l_1}^{(6)}$. The colored phase diagrams contain some multicritical Lifshitz points that are at nonzero temperature and many modulated new phases. We also investigate the variation of the wave vector with temperature in the modulated phase and the Lyapunov exponent associated with the trajectory of the system.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 114-118
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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