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1
Content available remote

An Investigation of the The dynamic Young Moduli of Twisted Fibres

100%
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.
2
Content available remote

Temperature Dependent Anharmonic Properties of Lead Chalcogenides

100%
Raju K.
Acta Physica Polonica A
|
2010
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vol. 118
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issue 4
600-605
EN
Calculations were made to investigate the anharmonic properties of lead chalcogenides PbS, PbSe and PbTe at elevated temperatures by means of primary physical parameters viz. nearest-neighbour distance and hardness parameter using long- and short-range potentials. Higher-order elastic constants are computed up to their melting temperature for these crystals. The first order pressure derivatives of second- and third-order elastic constants, the second-order pressure derivatives of second-order elastic constants and partial contractions are also evaluated at different temperatures. As the experimental elastic constants are not available at high temperatures, hence our results were only compared with the available values obtained at room temperature. The nature of the elastic behaviour in these compounds was analyzed.
3
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Anomalous Phase Transitions in LiCsSO_4 in the Compressible hcp Ising Model

80%
Lehmann-Szweykowska A., Kurzyński M., Wojciechowski R., Wiesner M., Mróz B.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1108-1110
EN
Structural low-temperature phase transformations in LiCsSO_4 are analysed in a newly tailored simple model of the static soliton in the periodically modulated phases of the one-dimensional compressible Ising model. It is shown that the original hcp symmetry is crucial for understanding of the anomalous temperature-dependence of the Brillouin shift.
4
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On the Structural Phase Transition in a Perovskite-Type Diaminopropanetetrachlorocuprate(II) NH₃(CH₂)₃NH₃CuCl₄ Crystal

80%
Czupiński O., Ingram A., Kostrzewa M., Przesławski J., Czapla Z.
Acta Physica Polonica A
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2017
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vol. 131
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issue 2
304-310
EN
Chemical preparation, differential scanning calorimetry and thermal stability differential thermal gravimetry studies, positron annihilation lifetime investigations, optical observations as well as electric properties of the NH₃(CH₂)₃NH₃CuCl₄ crystal are presented. On the basis of the differential scanning calorimetry response the structural phase transition of the first order was observed at 436 K. The enthalpy and entropy of the phase transition are equal to 1120 J/mol and 2.57 J/(mol K), respectively. Differential thermal analysis and thermogravimetric analysis studies confirmed the phase transition at 436 K and one can conclude the chemical and thermal stability of the compound up to about 480 K. Optical observations showed a continuous change of colour from yellow to dark brown above the phase transition to 436 K. Dielectric measurements showed a significant increase of conductivity upon approaching the phase transition regions, with a significant increase above the phase transition temperature. An activation energy dependent on the temperature range, and different for each particular phase, is obtained from measurements of complex impedance.
5
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Mechanical Characteristics of As₂S₃ Glasses Induced by Doping with Bismuth

80%
Šiljegović M., Lukić-Petrović S., Petrović D., Videnović I., Turyanytsa I.
Acta Physica Polonica A
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2016
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vol. 129
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issue 4
488-491
EN
This paper presents and discusses the results of the instrumented indentation test of the samples of the system Bi_{x}(As₂S₃)_{100-x}, x= 1.5, 3, 5, and 7 at.%. Measurements of mechanical parameters were performed using a Fischerscope HM2000 S nanoindentation device. The experimental data obtained by measuring the microhardness parameters were used to determine some other mechanical quantities that are important for the characterization of the examined materials in terms of their potential applications. For the first three compositions, the results indicated an increase in the microhardness with the increase in the content of doping atoms, which can be interpreted as an enhancement of the strength and stiffness of the structural network. The lower value of microhardness of the sample with the maximum content of Bi can BE associated with the specific structure of this composition. The pronounced indentation size effect was also detected on the indentation curve in the range of smaller loads. According to the model of elastic-plastic deformation, applied for the description of indentation size effect measured for the investigated chalcogenides, the largest value of the elastic recovery was observed for the sample Bi₇(As₂S₃)₉₃. The calculated values of the elasticity modulus show that the glass with x= 5 at.% Bi is characterized with the highest atomic packing density.
6
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Pressure Dependence of the Light Emission in Zinc-Blende InGaAs/GaAs and InGaN/GaN Quantum Wells

80%
Łepkowski S., Gorczyca I.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
857-858
EN
We present theoretical study of the pressure coefficient of the light emission (dE_{E}/dP) in compressively strained zinc-blende InGaAs/GaAs and InGaN/GaN quantum wells, grown in a (001) direction. We investigate the contributions to dE_{E}/dP arising from (i) third-order (nonlinear) elasticity, (ii) nonlinear elasticity, originating from pressure dependence of elastic constants, and (iii) nonlinear dependence of elastic constants on composition in InGaAs and InGaN alloys. The obtained results indicate that the use of nonlinear elasticity is essential for determination of dE_{E}/dP in the strained InGaAs/GaAs and InGaN/GaN quantum wells, while the inclusion of the nonlinear dependence of elastic constants on composition of InGaAs and InGaN alloys does not improve agreement between the theoretical end experimental values of dE_{E}/dP in the considered structures.
7
Content available remote

Thermoelectric Properties of Ca_3Co_4O_9-Based Ceramics Doped with Fe and/or Y

80%
Fedotov A., Fedotov A., Mazanik A., Svito I., Saad A., Troyanchuk I., Bushinski M., Fedotova V., Zukowski P., Koltunowicz T.
Acta Physica Polonica A
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2014
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vol. 125
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issue 6
1344-1347
EN
We describe here structure and temperature dependences of conductivity σ(T), the Seebeck coefficient α(T), thermal conductivity λ(T) and figure-of-merit ZT(T) in Ca_3Co_4O_9 ceramics, doped with Fe and Y, depending on compacting pressure (0.2 or 6 MPa) and temperature (300 < T < 700 K). It is shown that introduction of iron and yttrium to ceramics does not alter the crystalline structure of the material. Increasing the pressure in the compacting process before the additional diffusion annealing leads to a smaller-grained structure and increase σ and λ due to reducing of the synthesized samples porosity. The Seebeck coefficients of nanocomposite ceramics Ca_3Co_{3.9}Fe_{0.1}O_9 and (Ca_{2.9}Y_{0.1})(Co_{3.9}Fe_{0.1})O_9 have linear dependences on temperature is not changed after increase of compacting pressure. Electrical-to-heat conductivity ratio (σ/λ) for the samples compacted at high (6 GPa) pressure increases not more than 20-30% in comparison with ones compacted at low (0.2 GPa) pressure, whereby ZT is increased more than 50%. The main reason for this effect is samples porosity reduction with the compacting pressure increase.
8
Content available remote

Image Force Effect on the Separation of Partial Dislocations in Bicrystals of Hexagonal Structure Zn-Tl and Zn-Be

80%
Ayadi A., Khalfallah O.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
302-303
EN
We study the elastic interaction between a pair of partial dislocations, resulting from the dissociation of a perfect dislocation, and a bimetallic interface. The forces that act on two partials dislocations are the forces due to elastic interaction between the partial and image forces due to interactions of partial dislocations with interface. We are interested in the effect of image force on width of the stacking fault ribbon between two Schockley partials. We show that the separation of two partials dislocations is modified compared to that in the single crystal. It depends on the ratio of shear modulus and the distance between the interface and the dislocation.
9
Content available remote

Elastic and Thermodynamic Properties of Anti-Perovskite Type Superconductor MCNi_3 (M = Zn, Cd)

80%
Duan M., Tan J., Ji G., Chen X., Zhu J.
Acta Physica Polonica A
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2010
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vol. 118
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issue 4
652-658
EN
The elastic and thermodynamic properties of the anti-perovskite superconductor ZnCNi_3 and CdCNi_3 are investigated by first-principles calculations. With the local density approximation as well as the generalized gradient approximation for exchange and correlation, the ground state properties and equation of state are obtained, which agree well with other theoretical calculations and experiments. Furthermore, by the elastic stability criteria, we predict that ZnCNi_3 and CdCNi_3 are not stable above 98.1 GPa and 196.5 GPa, respectively. The dependences of the heat capacity, thermal expansion coefficient, the Grüneisen parameter and bulk modulus (B_{T} and B_{S}) on pressure and temperature for ZnCNi_3 and CdCNi_3 are also obtained successfully.
10
Content available remote

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

80%
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.
11
Content available remote

Electric-Elastic Field Induced by a Straight Dislocation in One-Dimensional Quasicrystals

80%
Yang L., Gao Y., Pan E., Waksmanski N.
Acta Physica Polonica A
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2014
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vol. 126
|
issue 2
467-470
EN
By using the generalized Stroh formalism, the electric-elastic field induced by a straight dislocation parallel to a periodic axis of a one-dimensional quasicrystal is obtained. The derivation is concise and the solution is in an exact closed form. As an illustration, the electric-elastic fields around a straight dislocation in a one-dimensional hexagonal quasicrystal are studied. Besides the interesting numerical results presented, the generalized Stroh formalism can be applied to more complicated dislocation problems in quasicrystals.
12
Content available remote

[100] Loading of Fcc Based Nanofibre Reinforced Composites

70%
Černý M., Pokluda J.
Acta Physica Polonica A
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2012
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vol. 122
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issue 3
505-508
EN
Ab initio calculations of theoretical tensile and compressive strengths in the 〈100〉 direction of a composite having continuous nanofibre reinforcements are performed using pseudopotential approach within density functional theory. Results for iridium or platinum nanofibres in copper or gold matrices, presented as case studies, reveal that the theoretical tensile and compressive strengths almost linearly increase with increasing atomic concentration of the reinforcement exhibiting only slight positive strength deviations from the linearity for Pt-Au and slight negative deviations of the tensile strength for Ir-Cu.
13
Content available remote

Stress Monitoring in Steel Elements via Detection of AC Magnetic Permeability Changes

70%
Szumiata T., Hibner K., Dziewiecki K., Mazur Z., Gockiewicz A., Gzik-Szumiata M., Górka B., Witoś M.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
719-721
EN
The influence of mechanical stress on low frequency AC magnetic permeability was studied. The cold-drawn bars with C45 steel were subjected to investigation. The tensile stress (within elastic regime) was applied by means of material testing machine. Simple measuring system was assembled, which consisted of: function generator with magnetizing coil, detection coil and precise AC voltmeter. The registered changes of induced voltage were proportional to the change of magnetic permeability of the stretched rods. The obtained results were almost frequency-independent due to low frequency limit (250-500 Hz, weak eddy currents, no spin-origin energy dissipation). A significant magneto-mechanical hysteresis was observed slightly evolving from cycle to cycle with tendency of stabilization. The extension of basic Stoner-Wohlfarth model of magnetic permeability allowed to fit the data reproducing hysteretic behavior and considering the relaxation of the internal stress. The proposed, low-cost method is suitable in the industrial applications for stress control in large-sized steel elements.
14
Content available remote

Equivalence of Mechanical and Magnetic Force in Magnetic Shape Memory Effect

61%
Kopecký V., Perevertov O., Straka L., Ševčík M., Heczko O.
Acta Physica Polonica A
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2015
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vol. 128
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issue 4
754-757
EN
High mobility of twin boundary is crucial for magnetic shape memory effect. The twin boundary can be moved by applied magnetic field or mechanical stress. In Ni-Mn-Ga 10M martensite there are two different, field movable, a-c twin boundaries type I and II due to monoclinic lattice. For single twin boundary of both types we experimentally evaluated the equivalence of magnetic and mechanical force and the validity of generally used energy model using direct stress-strain and magnetization measurements. For type II, highly mobile twin boundary, the equivalence seems to be valid and model broadly agrees with measurement. However, for type I the calculated magnetic stress is much larger than mechanical stress needed for twin boundary motion.
15
Content available remote

First-Principles Study of Structural, Elastic and Mechanical Properties of Zinc-Blende Boron Nitride (B3-BN)

61%
Daoud S., Loucif K., Bioud N., Lebgaa N.
Acta Physica Polonica A
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2012
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vol. 122
|
issue 1
109-115
EN
First principles study of structural, elastic properties and anisotropy effect on the mechanical parameters of the zinc-blende boron nitride has been performed using the pseudopotential plane wave method based on density functional theory with the Teter and Pade exchange-correlation functional of the local density approximation. The equilibrium lattice constant, molecular and crystal densities, bond length, the independent elastic constants, bulk modulus and its pressure derivatives, compressibility, shear modulus, internal strain parameter, isotropy factor, compliance constants, the Debye temperature, Young's modulus, Poisson's ratio, the Lamé constants and sound velocity for directions within the important crystallographic planes of this compound are obtained and analyzed in comparison with the available theoretical data reported in the literature.
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