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1
Content available remote

Structural and Elastic Properties of Wurtzite Al-Rich In_{x}Al_{1 - x}N Alloys

100%
Łepkowski S., Gorczyca I.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
666-668
EN
We present theoretical study of lattice parameters and elastic constants of wurtzite Al-rich In_{x}Al_{1 - x}N (x = 0.125, 0.1875 and 0.25) alloys using self-consistent ab initio calculations with a supercell model. Two different atomic arrangements have been considered for a given x, by either distributing the In atoms as uniformly as possible over the supercell or by clustering the In atoms together in a small part of the supercell. Our calculations reveal that the a and c lattice parameters show almost linear dependence on composition for the alloys with uniform distribution of In atoms, while for the case of alloys with clustered In atoms the c lattice parameter deviates from linearity quite significantly. For the alloys with clustered In atoms, we observe that the values of C_{11}, C_{12}, and C_{44} elastic constants are significantly smaller than the linear interpolated values between the elastic constants of AlN and InN, and the values of C_{33} elastic constant are significantly larger than the corresponding interpolated values. For the alloys with uniform distribution of In atoms, only C_{11} elastic constant deviates significantly from linear dependence on composition.
2
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A Numerical Investigation of the Effect of Cubic Crystals Orientation on the Indentation Modulus

100%
Materna A., Haušild P., Nohava J.
Acta Physica Polonica A
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2015
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vol. 128
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issue 4
693-696
EN
The elastic finite element computations of the indentation process with the Berkovich indenter are performed to examine the effect of cubic crystal and indenter orientation on indentation moduli of anisotropic material. Three metals with a cubic crystal lattice and various degree of elastic anisotropy from 1 to 9 are studied: tungsten, AISI 304 steel and β -brass. Differences in anisotropy ratios expressed by the Young moduli on the one side and by the indentation moduli on the other side are quantified.
3
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An Investigation of the The dynamic Young Moduli of Twisted Fibres

63%
Wasilewski A., Więcek T.
Acta Physica Polonica A
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2015
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vol. 128
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issue 2
231-233
EN
This paper describes a modified laser system to measure the dynamic Young modulus and logarithmic decrement of damping for twisted fibers. A modified impulse mechanical spectrometer was designed and built by the authors. The effect of twisting on the values of the dynamic Young modulus and logarithmic decrement of damping was studied. The dynamic Young modulus and logarithmic decrement of damping were investigated for long PET fibers with a 200 μm diameter. This experimental method does not require calibration because it contains standard length which is the wavelength of the laser beam.
4
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First-Principle Study of Structural, Elastic Anisotropic, and Thermodynamic Properties of P4̅m2-BC₇

51%
Zhang Q., Wei Q., Yan H., Zhang Z., Fan Q., Jia X., Zhang J., Zhang D.
Acta Physica Polonica A
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2016
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vol. 129
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issue 3
329-333
EN
The structural, elastic anisotropy and thermodynamic properties of the P4̅m2-BC₇ are investigated using first-principles density functional calculations and the quasi-harmonic Debye model. The obtained structural parameters and elastic modulus are in consistency with the available theoretical data. Elastic constants calculations show that P4̅m2-BC₇ is elastic anisotropic. The bulk modulus as well as other thermodynamic quantities of P4̅m2-BC₇ (including the Grüneisen constant, heat capacity and thermal expansion) on temperatures and pressures have also been obtained.
5
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First Principles Study of Mechanical Stability and Thermodynamic Properties of K₂S under Pressure and Temperature Effect

51%
Boufadi F., Bidai K., Ameri M., Bentouaf A., Bensaid D., Azzaz Y., Ameri I.
Acta Physica Polonica A
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2016
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vol. 129
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issue 3
315-322
EN
First principles calculations on structural, elastic and thermodynamic properties of K₂S have been made using the full-potential augmented plane-waves plus local orbitals within density functional theory using generalized gradient approximation for exchange correlation potentials. The ground state lattice parameter, bulk moduli have been obtained. The second-order elastic constants, Young and shear modulus, Poisson ratio, have also been calculated. Calculated structural, elastic and other parameters are in good agreement with available data. The elastic constants and thermodynamic quantities under high pressure and temperature are also calculated and discussed.
6
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Elasticity Study of PAAm-κ C Composite Prepared in Various κ C Content and Measured at Several Temperatures

51%
Evingür G., Pekcan Ö.
Acta Physica Polonica A
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2015
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vol. 128
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issue 3
331-335
EN
Polyacrylamide (PAAm)-kappa carrageenan (κC) composite gels were prepared via free radical crosslinking copolymerization with various (w/v) percentages of κC in the range between 0.5 and 3 (w/v)% of κC. Elasticity properties such as stress, strain and compressive elastic modulus, S of these composite gels were studied in various κC content and at several temperatures. The content and temperature dependence of the compressive elastic modulus, S of the swollen PAAm-κC composite gels due to volume phase transition were produced by using tensile testing technique. It is understood that the compressive elastic modulus was found to decrease up to 1 (w/v)% of κC, and then increase by increasing κC contents, at constant temperatures. The composite preserves the ability to undergo the volume phase transition and its compressive elastic modulus is found to be strongly dependent on the κC content and temperature. It is observed that the compressive elastic modulus increased when temperature is increased up to 40°C and then decreases below this temperature for all composite gels. However, PAAm-κC composite gel presented lower values for the compressive elastic modulus, showing a minima at 40°C for 1 (w/v)% of κC content gel.
7
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A New Potential Superhard Phase of OsN_2

51%
Fan Q., Wei Q., Yan H., Zhang M., Zhang D., Zhang J.
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vol. 126
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issue 3
740-747
EN
A new phase of C2/m OsN_2 is proposed in this paper. The crystal structure, elasticity and electronic properties of C2/m OsN_2 were studied by first-principles calculations. The elastic constants, the elastic moduli (B, G, and E) and Poisson's ratio v of OsN_2 have been investigated. From the first-principles calculations, we find that C2/m OsN_2 is metallic and mechanically stable. The quasi-harmonic Debye model, using a set of total energy versus molar volume obtained from the first-principles calculations, is applied to the study of the thermal and vibrational effects. The dependence of structural parameters, thermal expansions, heat capacities, Grüneisen parameters and Debye temperatures on the temperature and pressure are obtained in the whole pressure range from 0 to 80 GPa and temperature range from 0 to 800 K as well as compared with available data.
8
Content available remote

Poisson Ratio and Biaxial Relaxation Coefficient in In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N Alloys

51%
Łepkowski S., Gorczyca I.
Acta Physica Polonica A
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2011
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vol. 120
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issue 5
902-904
EN
We present theoretical results showing dependence of Poisson ratio and biaxial relaxation coefficient on composition and atomic arrangement in wurtzite In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N alloys. Our calculations reveal that the Poisson ratio determined for In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N alloys subjected to a uniaxial stress parallel to the c axis of the wurtzite structure shows significant superlinear dependence on composition. The superlinear bowing in Poisson ratio is enlarged by the effect of In clustering. The biaxial relaxation coefficient determined for In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N alloys subjected to a biaxial stress in the plane perpendicular to the c axis of the wurtzite structure changes superlinearly and linearly with x in In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N, respectively. The effect of In atom clustering results in sublinear dependence of the biaxial relaxation coefficient in both In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N alloys.
9
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The Pressure Induced B1-B2 Phase Transition of CdO

51%
Bhardwaj P.
Acta Physica Polonica A
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2013
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vol. 124
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issue 4
677-684
EN
In this paper, the structural, elastic and thermodynamic properties of CdO under different pressure range have been reported. An extended interaction potential model (including the zero point energy effect) has been used for this study. Phase transition pressures are associated with a sudden collapse in volume. At compressed volume, the present oxide is found in cesium chloride (CsCl) phase. The calculated second order elastic constants and their various combinations have been reported in different pressure range. The calculated values have been compared with available results. Our values have been found in good agreement with existing findings.
10
Content available remote

Structural Study of Transition Metal Carbides

51%
Bhardwaj P.
Acta Physica Polonica A
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2012
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vol. 122
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issue 1
138-141
EN
In this research paper we have discovered the structural phase transition and elastic properties of transition metal carbides (TaC and HfC). Phase transition pressures are associated with a sudden collapse in volume showing the incidence of first order phase transition. At ambient condition the present compounds exhibit rock salt (NaCl) structure, they transform into cesium chloride (CsCl) structure under high pressure. The phase transition pressures and associated volume collapses obtained from present potential model show a generally good agreement with the available literature. The elastic constants and bulk modulus are also reported for the present compounds.
11
Content available remote

Effect of Temperature on Non-Destructive Wave Propagation in Uranium Monopnictides

51%
Singh R., Singh R., Singh M., Chaurasia S.
Acta Physica Polonica A
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2009
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vol. 115
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issue 3
664-670
EN
Acoustic attenuation due to phonon-phonon interaction, thermoelastic mechanism and dislocation damping were evaluated in uranium monopnictides (viz. UN, UAs and USb) in the temperature range 50-500 K, along the three crystallographic directions of propagation, viz. [100], [110] and [111] for longitudinal and shear modes of propagation. Due to antiferromagnetic property of these compounds ultrasonic attenuation due to magnon-phonon interaction was also obtained. The second- and third-order elastic moduli of B1-type uranium monopnictides were obtained using electrostatic and the Born repulsive potentials. Gruneisen numbers and acoustic coupling constants were evaluated for longitudinal and shear waves along different directions of propagation and polarization. Results were discussed and compared with available data. It was found that the temperature dependence of attenuation due to phonon-phonon interaction and thermoelastic loss mechanisms follow the third and fourth order polynomial fit laws, respectively, and acoustic attenuation is mainly governed by phonon-phonon interaction in this temperature range.
12
Content available remote

Preparation of Fine-Grained Silicon-Nitride Ceramics and their Characterization by Depth-Sensing Indentation Tests

51%
Şahin O., Güder H., Uzun O., Şahin E., Sopicka-Lizer M., Göçmez H., Artunc E.
Acta Physica Polonica A
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2015
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vol. 128
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issue 2B
B-355-B-359
EN
Both pressureless-sintered and dense, fine-grained silicon nitride ceramics were produced from mechanochemically activated nitride-based precursors. Scanning Electron Microscopy (SEM), Transmition Electron Microscopy (TEM), X-Ray Diffraction (XRD) and an ultra-low load microhardness tester were used to characterize these ceramics. Depth-sensing indentation (DSI) tests in the range of 200-1800 mN were performed on the silicon nitride ceramic to determine dynamic hardness (H_d) and reduced elastic modulus (E_r) values. These values were deduced by analyzing the unloading segments of the DSI curves. It was found that both H_d and E_r exhibits a significant indentation load dependence. Nix-Gao (NG) model was used to analyze the dynamic hardness data in the calculation of the load independent hardness value.
13
Content available remote

Ab Initio Study of the Mechanical, Thermal and Optoelectronic Properties of the Cubic CsBaF₃

51%
Harmel M., Khachai H., Haddou A., Khenata R., Murtaza G., Abbar B., Bin Omran S., Khalfa M.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1
34-42
EN
We have investigated the structural, elastic, electronic, optical and thermal properties of CsBaF₃ perovskite using the full-potential linearized augmented plane wave method within the generalized gradient approximation and the local density approximation. Moreover, the modified Becke-Johnson potential (TB-mBJ) was also applied to improve the electronic band structure calculations. The ground state properties such as lattice parameter, bulk modulus and its pressure derivative were calculated and the results are compared with the available theoretical data. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young's modulus and Poisson's ratio are obtained for the first time. Electronic and bonding properties are discussed from the calculations of band structure, density of states and electron charge density. The contribution of the different bands was analyzed from the total and partial density of states curves. The different interband transitions have been determined from the imaginary part of the dielectric function. The thermal effect on the volume, bulk modulus, heat capacities C_V and the Debye temperature was predicted using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account.
14
Content available remote

Microhardness and the Young Modulus of Thin, MBE-Grown, (Sn,Mn)Te Layers Containing up to 8% of Mn

51%
Adamiak S., Zięba M., Minikayev R., Reszka A., Taliashvili B., Szuszkiewicz W.
Acta Physica Polonica A
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2017
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vol. 132
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issue 2
347-350
EN
The thin layers of (Sn,Mn)Te solid solution were grown by molecular beam epitaxy onto (111)-oriented BaF₂ substrates and characterized by scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectrometry, and X-ray diffraction methods. The epitaxial character of the growth was confirmed. All the layers exhibited a regular (fcc) structure of the rock-salt type and were (111)-oriented, their thickness was close to about 1 μm. The layers contained up to 8% of Mn. The microhardness and the Young modulus values were determined by the nanoindentation measurements. The Berkovich type of the intender was applied, the maximum applied load was equal to 1 mN. The results of measurements demonstrated a lack of the composition dependence of the Young modulus value. A slight increase of the microhardness value with an increasing Mn content in the (Sn,Mn)Te solid solution was observed.
15
Content available remote

TBI Calculations of the Elastic Properties and Structural Phase Transformation in Novel Materials: Yttrium Nitride

51%
Singh S., Chauhan R., Gour A.
Acta Physica Polonica A
|
2011
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vol. 120
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issue 6
1021-1025
EN
We have carried out high pressure theoretical structural studies of yttrium nitride to examine the phase transition phenomena from the NaCl structure to CsCl structure by using a three-body potential model. The phase transition pressure (140 GPa) predicted by this approach is close to the phase transition pressure, predicted by others (138 GPa). Yttrium nitride is a novel and less explored material. Under high pressure yttrium nitride goes through a sudden collapse in volume showing the first order phase transition. To understand the effect of pressure we studied bulk properties, elastic constants and their combination. The pressure volume equation of state provides meaningful signatures of physical and chemical phenomena under high pressure. Moreover we have successfully checked the stability criterion for this compound.
16
Content available remote

First-Principles Calculations on Phase Transition and Elastic Properties of CoN

51%
De-Chun H., Yong P., Su-Yuan L., Yong-Lin H.
Acta Physica Polonica A
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2016
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vol. 130
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issue 3
743-747
EN
The structural phase transition and elastic properties of CoN are investigated by ab initio plane-wave pseudopotential density function theory method. The equilibrium lattice parameters a₀, elastic constants C_{ij}, bulk modulus B₀ and its derivative B'₀ are calculated. From the usual condition of equal enthalpy, the phase transition of CoN from zinc-blende to rocksalt structure occurs at 35.4 GPa with a volume collapse of about 15.6%, consistent with the calculated result 36 GPa (FP-LDA), but an uncertainty is about 4.4 GPa compared with the 31 GPa (ASA-GGA). All three independent elastic constants, C₁₁, C₁₂, and C₄₄ for CoN are calculated from direct computation of stresses generated by small strains. Both C₁₂ and C₄₄ are less sensitive to pressure as compared with C₁₁. The calculated conclusions offer theoretical data for the further research of the mechanical properties for CoN.
17
Content available remote

Vickers and Knoop Indentation Microhardness Study of β-SiAlON Ceramic

51%
Güder H., Şahin E., Şahin O., Göçmez H., Duran C., Ali Çetinkara H.
Acta Physica Polonica A
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2011
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vol. 120
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issue 6
1026-1033
EN
In this paper, analysis and interpretation of mechanical property measurements of β-SiAlON ceramic were reported. Indentation microhardness of β-SiAlON ceramic was measured using the Knoop and Vickers indenters. The analysis of the Vickers indentation microhardness data reveals the reverse indentation size effect that is the apparent microhardness increases with increasing applied indentation test load. However, the Knoop indentation microhardness data exhibit indentation size effect that is the apparent microhardness increases with decreasing applied test load. The experimental Knoop microhardness data was analyzed using Meyer's law, elastic-plastic deformation model, proportional specimen resistance model, and Hays-Kendall's model. As a result, modified proportional specimen resistance model is found to be the most effective one for the load-independent (H_{LI}) microhardness determination of the SiAlON ceramic. It was seen that different models used to analyze the data obtained from the Vickers indentation do not give the same intrinsic hardness value. We also present the calculation of the Young modulus, E, of the β-SiAlON ceramic.
18
Content available remote

Elastic Anisotropic and Thermodynamic Properties of I-4m2-BCN

51%
Xing M., Li B., Yu Z., Chen Q.
Acta Physica Polonica A
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2016
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vol. 129
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issue 6
1124-1130
EN
Based on the density functional theory and the quasi-harmonic Debye model, the structural and thermodynamic properties of I-4m2-BCN have been studied in this paper. Some structural parameters are presented in this work. All of these results are in excellent agreement with the other available results. The anisotropy of elastic properties are also studied systematically in this paper. Finally, the thermodynamic properties of I-4m2-BCN are also researched through the quasi-harmonic Debye model. The relations among the thermal expansion α, the Debye temperature Θ_{D}, the heat capacity C_V and C_P, the Grüneisen parameter γ , entropy S, and the Gibbs free energy G with pressure P and temperature T are studied systematically.
19
Content available remote

Characterization of Date Palm Wood Used as Composites Reinforcement

51%
Almi K., Lakel S., Benchabane A., Kriker A.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1072-1074
EN
This work reports the results of an experimental investigation on physical and mechanical properties of Algerian date palm tree residues in order to optimize their performances when used as reinforcement. The results have shown that all the samples are characterized by porous and fibrous structure with irregular surface, which contains a large number of uncompleted grown fibers (expected to be residual lignin). Concerning the mechanical properties of date palm fibers (DPF), the results show that they are comparable to those reported for coir and are lower than those reported for other natural fibers. However with regard to the specific mechanical properties, date palm fibers show higher values than those of other natural fibers. This is due to the low values of bulk density of date palm wood, especially of that of Petiole.
20
Content available remote

Ab Initio Studies on Structural, Elastic, Thermodynamic and Electronic Properties of FeCrAs under Pressures

51%
He D.-C., Peng Y., He Y.-W.
Acta Physica Polonica A
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2015
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vol. 127
|
issue 6
1637-1644
EN
The structural, elastic, thermodynamic and electronic properties of nonmetallic metal FeCrAs are studied within density function perturbation theory. The thermodynamic properties of FeCrAs were deduced based on phonon frequencies within the framework of the quasiharmonic approximation. The calculated elastic modulus under various pressures indicates that FeCrAs is mechanically stable under pressure. The pressure-dependence of bulk and shear modulus, transverse and longitudinal sound velocities V (i.e. V_{S} and V_{L}), elastic Debye temperature Θ_{E} of FeCrAs have also been investigated. The calculated values of B/G indicate that FeCrAs presents high ductility under pressure. However, it is interesting that the value of B/G reaches a maximum under 40 GPa and almost remains unchanged when the pressure is above 70 GPa. The calculations show that the heat capacity C_{V} of this material is close to the Dulong-Petit limit 3R (about 224.61 J mol^{-1} K^{-1}) at high temperature regime. The analysis of electronic properties find that as the pressure increases, the absolute value of charge for As and Fe atom increases while Cr remains nearly a constant, indicating that the mechanic properties of FeCrAs under pressure should be mostly attributed to the interaction between Fe and As atoms.
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