Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl

Refine search results

Journals help

  1. 42 Acta Physica Polonica A

  2. 2 Open Physics

Years help

  1. 2 2016

  2. 1 2015

  3. 2 2014

  4. 2 2013

  5. 1 2011

More...
Authors help

  1. 5 Dynowska E.

  2. 5 Szuszkiewicz W.

  3. 4 Jouanne M.

  4. 3 Hennion B.

  5. 3 Komarov F.

More...
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 44

Number of results on page
first rewind previous Page / 3 next fast forward last

Search results

Search:
in the keywords:  63.20.-e
help Sort By:

help Limit search:
first rewind previous Page / 3 next fast forward last
1
Content available remote

The Lattice Dynamics of Ni-24%Fe Alloy Based on an Empirical Many-Body Potential

100%
Akgün İ., Uğur G.
Acta Physica Polonica A
|
1999
|
vol. 96
|
issue 3-4
391-398
EN
We have developed an empirical many-body potential and used it to investigate the dynamical behaviours of fcc Ni-24%Fe alloy. The new many-body potential contains both two- and three-body atomic interactions. The two-body potential is expressed by the modified form of the generalized Morse potential and the three-body potential is developed based on the new two-body model potential. The parameters defining the many-body potential for Ni and Fe were computed following a procedure similar to the method defined by Akgün and Uğur for fcc structure at the lattice constant of the alloy. The radial, tangential and three-body force constants of the alloy were calculated by the concentration averages of the computed force constants of the component metals. Finally, the phonon frequencies of the alloy along the principal symmetry directions were computed using the calculated two- and three-body force constants. The theoretical results were found to be in good agreement with the corresponding experimental values.
2
Content available remote

Determination of Vibrational Eigenfrequencies of Semiconductors Using Tight-Binding Total Energy Calculations

100%
Stephan J., Suisky D.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 5
1075-1079
EN
We calculate the eigenfrequencies of bulk semiconductors using tight-binding total energy calculations of an ideal and a distorted lattice. We correlate the obtained energy change with the harmonic force constants appearing as parameters in the expansion of the potential energy of the crystal lattice in terms of the displacement. A good agreement of the calculated q = 0 optical vibrational modes with the experimental values for Si, Ge, GaAs and GaP bulk crystals is obtained. The influence of a surface on the force constants and the vibrational frequencies is studied.
3
Content available remote

Phonon Dispersion in Cu-Zn Alloy

100%
Akgün I.
|
EN
Phonon dispersion curves for fcc Cu-25% Zn alloy were calculated using deLauney angular force model, the analysis being limited to the second neighbour interactions only. In the present calculations the elastic constants of Cu and Zn in fcc and hcp phases, respectively, were used to evaluate the force constants of the alloy system. Satisfactory agreement between theory and experiment is obtained.
4
Content available remote

Lattice Dynamical Calculations for Li_{1+x}Ti_{2-x}O_4 (x=0.33) and Li_{1-y}Mg_{y}Ti_2O_4 (y=0.1, 0.3)

100%
Kushwaha A.
Acta Physica Polonica A
|
2013
|
vol. 124
|
issue 4
695-697
EN
Zone-centre Raman and infrared phonon frequencies for the spinel phases of oxides Li_{1+x}Ti_{2-x}O_4 (x=0.33) and Li_{1-y}Mg_{y}Ti_2O_4 (y=0.1, 0.3) of space group Fd3m have been calculated using a proposed short-range force constant model. In this model, the lattice potential energy is expanded using Taylor's expansion in the harmonic approximation. The calculated zone-centre phonon frequencies are in good agreement with the available experimental and previously calculated results.
5
Content available remote

Lattice Dynamical Calculations for Inverse Spinel Compounds

100%
Kushwaha A.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 3
741-743
EN
Lattice dynamical calculations have been performed for inverse spinel structure compounds MIn_{2}S_{4} (M = Mn and Co) using the proposed six parameter bond-bending force constant model. In this model, the short-range force constant is calculated by using the Taylor expansion of the potential energy in the harmonic approximation. This model is applied to study the zone-centre (Γ=0) phonon frequencies of inverse spinels MIn_{2}S_{4} (M = Mn and Co). The significant outcome of the present work is that the second neighbor interactions (octahedral bonding) are stronger than the first neighbor interactions (tetrahedral bonding). The zone-center phonon frequencies, calculated using these parameters, are found to be in very good agreement with the observed results.
6
Content available remote

Raman Scattering Photonic and Polaritonic Resonances in Semiconductor Microcavities

63%
Jusserand B., Fainstein A.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 4
685-693
EN
Single and double optical resonant Raman scattering is demonstrated in semiconductor microcavities. Its evolution towards excitonic ingoing resonance relies on cavity-polaritons as intermediated steps of the inelastic scattering. Implications for high-sensitivity spectroscopy and low-power stimulated processes are emphasized.
7
Content available remote

Effect of Layered Structure on the Lattice Heat Capacity of the Rare Earth Molybdates

63%
Feher A., Stefányi P., Orendáčová A., Anders E. E., Zvyagin A. I.
Acta Physica Polonica A
|
1991
|
vol. 79
|
issue 6
861-867
EN
Temperature dependence of the heat capacity of layered rare earth molybdates was measured in the temperature range from 0.4 K to 23 K. It is shown that the temperature dependence of the lattice heat capacity can be described by the "T", where n ≠ 3. It is shown that differently from KDy(MoO_{4})_{2} and CsDyEu(MoO_{4})_{2} for CsDy(MoO_{4})_{2} and CsGd(MoO_{4})_{2} we obtained the temperature term with n < 3, which can be connected with the 2D behaviour, manifested also in the so-called membrane effect.
8
Content available remote

Lattice Dynamics of Alkali Metals in a Three-Body Interaction

63%
Coelho A. A., Shukla M. M.
Acta Physica Polonica A
|
1995
|
vol. 87
|
issue 3
599-609
EN
The original model of Das et al. is modified in extending the electron-ion interaction on a three-body forces and including the crystal equilibrium con­dition to reduce one independent parameter. We studied the phonon dis­persion relations along the three principal symmetry directions i.e. [ξ,0,0], [ξ,ξ,0] and [ξ,ξ,ξ] and θ-T curves of alkali metals, Na, K, Rb, Cs and Li. There is close agreement between the computed results and the experimental observations.
9
Content available remote

Characterization and Selected Physical Properties of CdTe/MnTe Short Period Strained Superlattices

63%
Szuszkiewicz W., Dynowska E., Bąk-Misiuk J., Karczewski G., Wojtowicz T., Kossut J., Jouanne M.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 5
1090-1094
EN
Phonon excitations in (CdTe)_{12}/(MnTe)_{n} (100) superlattices (n=2, 4, 8) were investigated at 295 K and 25 K with the use of Raman scattering. From the "folded" phonon frequencies the elastic constant c_{11} value for MnTe was estimated. The strain arising from lattice mismatch (determined by X-ray diffraction) results in shifts of MnTe and CdTe "confined" LO phonon frequencies. For the precise determination of LO phonon dispersions an additional shift due to Mn diffusion at the CdTe/MnTe interface should be taken into account.
10
Content available remote

Reflectivity Studies of Lattice Vibrations and Free Electrons in MBE Grown GaN Epitaxial Layers

63%
Iller A., Jantsch W., Marks J., Pastuszka B., Diduszko R.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 2
336-340
EN
We have observed a sharp structure with a peak at the frequency of the E_{1}-TO phonon in the reflectivity of GaN epitaxial layers grown by molecular beam epitaxy on Si substrates. The simulations of the reflection performed show that the observed shape can be explained by assuming both collective lattice vibrations and free carriers contributions to the dielectric function. We assumed the Lorentz oscillator to describe the contribution of the collective lattice vibrations and the Drude-Lorentz model for that of free carriers. Fitting the calculated reflectivity to the spectrum obtained experimentally allowed us to evaluate lattice and free carrier parameters.
11
Content available remote

An Investigation of Optical Vibrations in Zn_{3}P_{2}

63%
Misiewicz J., Wrobel J., Clayman B.
Acta Physica Polonica A
|
1991
|
vol. 79
|
issue 2-3
405-409
EN
Reflectivity and transmittivity spectra of Zn_{3}P_{2} in the far infrared region were measured at several temperatures. Raman scattering spectra at 295 K were also measured. Results of these measurements were interpreted in terms of one-phonon and multi-phonon transitions.
12
Content available remote

Pre-Melting in Cubic Structure with Relaxation

63%
Gwizdałła T., Czerbniak J.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 5-6
785-793
EN
We study the effect of melting of well-defined crystal surface within the frame of theory of atomic vibrations in harmonic approximation. We find that for two types of cubic crystal lattice: face centered cubic and body centered cubic, we may expect the existence of pre-melting. It is also shown that the occurrence or absence of surface melting depends strongly on the relaxation of lattice constant.
13
Publication available in full text mode
Content available

Ab Initio Lattice Dynamics of MgB_2

63%
Parlinski K.
Acta Physica Polonica A
|
2001
|
vol. 100
|
issue 5
767-772
EN
Using the density functional theory, the phonon dispersion relations, the phonon density of states, mean square displacements, and thermodynamic functions of superconducting MgB_2 crystals have been calculated. The modes of graphite-like boron network belong to optic phonon branches, which are rather independent of the Mg vibrations.
14
Content available remote

Influence of Correlated Thermal Vibrations on Temperature Dependence of Surface Peak

63%
Gwizdałła T., Czerbniak J.
Acta Physica Polonica A
|
1996
|
vol. 89
|
issue 1
61-67
EN
The influence of correlation between thermal displacements of atoms in string on the calculated Rutherford backscattering spectra under channelling conditions was studied. This correlation was incorporated into the existing Monte Carlo computer code by means of sampling the displacements from distribution transformed by the variance-covariance matrix. Various methods of implementing the correlation into calculation were used. As a result the deformation of energy spectrum was obtained. The explicit decrease in surface peak due to the correlation was observed. The significance of this effect decreases with increasing temperature. Calculation were performed in a wide region of temperatures, up to the melting point.
15
Content available remote

Lattice Dynamics of Cubic Mercury Sulphide

63%
Szuszkiewicz W., Dybko K., Dynowska E., Górecka J., Witkowska B., Hennion B.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 5
947-950
EN
The acoustic phonon dispersion of mercury sulphide of zinc-blende structure (β-HgS) was studied by inelastic neutron scattering. The measurements were carried out at 19 K and 295 K on HgS crystals doped with Fe. A slight decrease in phonon frequencies with increasing temperature was found, the temperature dependence being the strongest for LA phonons with [ξ,ξ,0] propagation. From acoustic phonon dispersion the values of selected elastic constants were determined for β-HgS.
16
Content available remote

Ab initio Calculations of Phonon Dispersion Relations in Aluminium

63%
Scharoch P., Parliński K., Kiejna A.
Acta Physica Polonica A
|
2000
|
vol. 97
|
issue 2
349-354
EN
A direct method and ab initio force constants were used to calculate phonon dispersion curves and phonon density in Al. The force constants were determined from the Hellmann-Feynman forces induced by the displacement of an atom in the 2×2×2 fcc crystallographic supercell. This size of the supercell gives exact phonon frequencies at Γ, X, L, W points of the Brillouin zone. The calculated phonon dispersion curves are in good agreement with the experimental data.
17
Content available remote

Lattice Dynamics of Noble Metals on Effective Three-Body Interaction

63%
Coelho A., Shukla M.
Acta Physica Polonica A
|
1996
|
vol. 89
|
issue 5-6
615-623
EN
Quite recently we modified the original model of Sarkar et al. for cubic metals in extending the ion-ion interaction, ion-electron interaction and the introduction of crystal equilibrium condition. We applied our scheme to alkali metals. We studied here the lattice dynamics of noble metals on our approach by calculating phonon dispersion relations along the three principal symmetry directions, [ξ00], [ξξ0] and [ξξξ] and the (θ-T) curves of three noble metals: copper, silver and gold. We obtained reasonable agreement with the experimental findings.
18
Content available remote

Study of SrLaAlO_{4} and SrLaGaO_{4} Substrate Crystals by Raman Spectroscopy

51%
Drozdowski M., Kozielski M., Pajączkowska A.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 1
139-142
EN
In this paper the study of SrLaAlO_{4} and SrLaGaO_{4} single crystals using the Raman scattering method is presented. The obtained results are discussed in terms of nature of the crystallografic imperfections and point defects which might arise during the crystal growth process.
19
Content available remote

Heat Capacity and Elastic Constants of Fe_{3-x}Zn_{x}O_{4} in the Vicinity of the Verwey Transition

51%
Kozłowski A., Kąkol Z., Schwenk H., Bareiter S., Hinkel C., Luthi B., Honig J.
Acta Physica Polonica A
|
2000
|
vol. 97
|
issue 5
883-887
EN
The results of the heat capacity and elastic constant studies of Fe_{3-x}Zn_{x}O_{4} (x<0.04) series are reported. Adiabatic heat capacity measurements, performed on single crystals, show the clear change of the transition character from first order for low Zn content (x<0.012) to the higher order in 0.012
20
Content available remote

Raman Scattering from ZnO(Fe) Nanoparticles

51%
Romčević N., Kostić R., Romčević M., Hadžić B., Kuryliszyn-Kudelska I., Dobrowolski W., Narkiewicz U., Sibera D.
Acta Physica Polonica A
|
2008
|
vol. 114
|
issue 5
1323-1328
EN
Nanocrystalline samples of ZnO(Fe) were synthesized by wet chemical method. Samples were characterized by X-ray diffraction to determine composition of the samples (ZnO, Fe₂O₃, ZnFe₂O₄) and the mean crystalline size (8-52 nm). In this paper we report the experimental spectra of the Raman scattering (from 200 to 1600 cm¯¹). Main characteristics of experimental Raman spectrum in 200 to 1600 cm¯¹ spectral region are: sharp peak at 436 cm¯¹ and broad two-phonon structure at ≈ 1150 cm¯¹, typical of ZnO;broad structure below 700 cm¯¹ that has different position and shape in case of ZnFe₂O₄ or Fe₂O₃ nanoparticles.
first rewind previous Page / 3 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.