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1
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Microhardness and the Young Modulus of Thin, MBE-Grown, (Sn,Mn)Te Layers Containing up to 8% of Mn

100%
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
|
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.
2
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Structural and elastic properties of barium chalcogenides (BaX, X=O, Se, Te) under high pressure

100%
Bhardwaj P., Singh S., Gaur N.
Open Physics
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2008
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vol. 6
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issue 2
223-229
EN
In the present paper we have investigated the high-pressure, structural phase transition of Barium chalcogenides (BaO, BaSe and BaTe) using a three-body interaction potential (MTBIP) approach, modified by incorporating covalency effects. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and associated volume collapses obtained from TBIP show a reasonably good agreement with experimental data. Here, the transition pressure, NaCl-CsCl structure increases with decreasing cation-to-anion radii ratio. In addition, the elastic constants and their combinations with pressure are also reported. It is found that TBP incorporating a covalency effect may predict the phase transition pressure, the elastic constants and the pressure derivatives of other chalcogenides as well.
3
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New parameters of many-body potentials: studying the thermal and mechanical properties of noble metals

100%
Qi X., Yan X.-S., Yang L.
Open Physics
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2010
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vol. 8
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issue 5
804-810
EN
New parameters of nearest-neighbor EAM (1N-EAM), n-th neighbor EAM (NN-EAM), and the second-moment approximation to the tight-binding (TB-SMA) potentials are obtained by fitting experimental data at different temperatures. In comparison with the available many-body potentials, our results suggest that the 1N-EAM potential with the new parameters is the best description of atomic interactions in studying the thermal expansion of noble metals. For mechanical properties, it is suggested that the elastic constants should be calculated in the experimental zero-stress states for all three potentials. Furthermore, for NNEAM and TB-SMA potentials, the calculated results approach the experimental data as the range of the atomic interaction increases from the first-neighbor to the sixth-neighbor distance.
4
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Ultrasonic wave propagation in rare-earth monochalcogenides

100%
Singh D., Pandey D., Yadawa P.
Open Physics
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2009
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vol. 7
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issue 1
198-205
EN
The ultrasonic attenuation in thulium monochalcogenides TmX (X=S, Se and Te) has been studied theoretically with a modified Mason’s approach in the temperature and range 100 K to 300 K along 〈100〉, 〈110〉 〈111〉 crystallographic directions. The thulium monochalcogenides have attracted a lot of interest due to their complex physical and chemical characteristics. TmS, TmSe and TmTe are trivalent metal, mixed valence state, and divalent semiconductor, respectively. Coulomb and Born-Mayer potential is applied to evaluate the second- and third-order elastic constants. These elastic constants are used to compute ultrasonic parameters such as ultrasonic velocities, thermal relaxation time, and acoustic coupling constants that, in turn, are used to evaluate ultrasonic attenuation. A comparison of calculated ultrasonic parameters with available theoretical/experimental physical parameters gives information about classification of these materials.
5
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Nanomechanical Comparison of Commonly Used Dental Crown Cements to a Newly Developed One

100%
Kale E., Arslanoğlu Z., Altan H., Bılgıç F., Tuzlali M., Köroğlu A., Özarslan S.
Acta Physica Polonica A
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2017
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vol. 132
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issue 3
954-958
EN
The main goal of nanoindentation tests is to obtain elastic modulus and hardness of the specimen material from load-displacement measurements. With this study, it was aimed to establish a quantitative relationship between the nanomechanical properties of commonly used dental cements in comparison to a newly developed crown cement and to predict its performance potential. Nanomechanical properties of polycarboxylate cement (PCC), glass-ionomer cement (GIC), dual-cure self-adhesive cement (SAC) and a newly developed glass-carbomer cement (GCC) were investigated by nanoindentation tests. All samples were fabricated according to their respective manufacturer's instructions. Available damage on the surface due to manipulation was removed by grinding with 1200, 2400 and 4000 grit sandpaper, and then polishing on 6, 3, and 1 μm diamond-lap-wheel was performed. Nano-mechanical measurements were done using nanoindenter machine with resolution less than 1 nN and displacement resolution of 0.04 nm. Berkovich diamond indenter tip was used for the nanoindentation tests. For each indentation, a set of nanoindentation tests at least on 6 different locations per specimen surface were performed to obtain more representative mean results. Indentation test load-displacement curves were analysed using Oliver-Pharr method, and one-way ANOVA or Kruskal-Wallis test, following Kolmogorov-Smirnov and Shapiro-Wilk, was used to compare the results. Nanohardness (H_{nano}) values were 0.52± 0.25, 0.45± 0.18, 1.03± 0.82 and 0.43± 0.18 GPa for GIC, GCC, PCC, and SAC, respectively. Reduced elastic modulus (E_{r}) values were 9.51± 6.17, 11.77± 5.04, 27.37± 20.61, 10.33± 5.08 GPa for GIC, GCC, PCC, and SAC, respectively. There was no statistical difference between the tested materials. PCC was the hardest, and GIC was the least hard material, whereas the newly developed GCC was the second, in terms of H_{nano}, before SAC. PCC also had the highest E_{r} mean, compared to the other dental crown cements, suggesting lower elastic properties. SAC was more elastic than GCC and less elastic than GIC. GCC had the second highest E_{r}, standing closer to SAC and GIC. Within the limitations of the current study, it can be concluded that the newly developed glass-carbomer cement is comparable to the other tested commonly used dental crown cements, regarding H_{nano} and E_{r}.
6
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Structural, electronic and elastic properties of Ti2TlC, Zr2TlC and Hf2TlC

84%
Bouhemadou A.
Open Physics
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2009
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vol. 7
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issue 4
753-761
EN
Using First-principle calculations, we have studied the structural, electronic and elastic properties of M2TlC, with M = Ti, Zr and Hf. Geometrical optimization of the unit cell is in good agreement with the available experimental data. The effect of high pressures, up to 20 GPa, on the lattice constants shows that the contractions are higher along the c-axis than along the a axis. We have observed a quadratic dependence of the lattice parameters versus the applied pressure. The band structures show that all three materials are electrical conductors. The analysis of the site and momentum projected densities shows that bonding is due to M d-C p and M d-Tl p hybridizations. The M d-C p bonds are lower in energy and stiffer than M d-Tl p bonds. The elastic constants are calculated using the static finite strain technique. We derived the bulk and shear moduli, Young’s modulus and Poisson’s ratio for ideal polycrystalline M2TlC aggregates. We estimated the Debye temperature of M2TlC from the average sound velocity. This is the first quantitative theoretical prediction of the elastic properties of Ti2TlC, Zr2TlC, and Hf2TlC compounds that requires experimental confirmation.
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