TEMPERATURE EFFECT ON THERMOMECHANICAL PROPERTIES OF BERYLLIUM CHALCOGENIDES BeS, BeSe AND BeTe

2006 ◽  
Vol 20 (01) ◽  
pp. 49-61 ◽  
Author(s):  
F. BENKABOU
Keyword(s):  
Elastic Constants ◽  
Dynamic Properties ◽  
Theoretical Calculations ◽  
Thermomechanical Properties ◽  
Structural Dynamic ◽  
Experimental Values ◽  
Beryllium Chalcogenides ◽  
Increasing Temperature ◽  
And Diffusion ◽  
Good Agreement

We have used the molecular-dynamic method for the calculation of the structural, dynamic and elastic properties of group BeS , BeSe and BeTe compounds for temperature ranging from 300 to 1200 K. Tersoff potential has been used to model the interaction between the groups II–VI compound atoms. The structural properties of cubic BeS , BeSe and BeTe have been calculated, and good agreement between the calculated and experimental values have been found. We have also predicted the elastic constants and diffusion coefficients of BeS , BeSe and BeTe . The values found compare very well with the theoretical results. For the temperature range under study, all elastic constants and dynamic properties show a softening with increasing temperature very similar to the theoretical calculations.

scholarly journals Synthesis, characterization and theoretical calculations of Cu(I) complex of trithiocyanuric acid [Cu(ttc)3]

2018 ◽  
Vol 23 (2) ◽  
pp. 241-266 ◽  
Author(s):  
Ximena Verónica Jaramillo-Fierro ◽  
César Zambrano ◽  
Francisco Fernández ◽  
Regino Saenz-Puche ◽  
César Costa ◽  
...  
Keyword(s):  
Computational Study ◽  
Theoretical Calculations ◽  
Photophysical Properties ◽  
Vibrational Frequencies ◽  
Basis Sets ◽  
Vertical Excitation ◽  
Experimental Values ◽  
Homo Lumo ◽  
Perchlorate Hexahydrate ◽  
Good Agreement

A new Cu(I) complex constructed by reaction of trithiocyanuric acid (ttc) and copper (II) perchlorate hexahydrate has been successfully synthesized by a slow sedimentation method in a DMF solvent at room temperature. The molecular structure of the compound was elucidated by MALDI-TOFMS, UV Vis and FTIR spectroscopy, DSC-TGA analysis and magnetic susceptibility measurement. The proposed structure was corroborated by a computational study carried out with the Gaussian09 and AIMAII programs using the RB3LYP hybrid DFT functional with both 6-31G and Alhrich-TZV basis sets. The calculated vibrational frequencies values were compared with experimental FTIR values. Photophysical properties of the synthesized complex were evaluated by UV-Visible spectroscopy and compared with computed vertical excitation obtained from TDDFT. The theoretical vibrational frequencies and the UV Vis spectra are in good agreement with the experimental values. Additionally, the Frontier Molecular Orbitals (HOMO-LUMO) and the Molecular Electrostatic Potential of the complex was calculated using same theoretical approximation. The results showed the interaction between three coordinatedl igand atoms and the Cu(I) ion.

scholarly journals Estimation of Activity Interaction Parameters in Fe-S-j Systems

Entropy ◽  
2018 ◽  
Vol 20 (10) ◽  
pp. 808 ◽  
Author(s):  
Tianhua Ju ◽  
Xueyong Ding ◽  
Yingyi Zhang ◽  
Weiliang Chen ◽  
Xiangkui Cheng ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Excess Entropy ◽  
Geometric Model ◽  
Calculation Model ◽  
Interaction Parameters ◽  
Mixing Enthalpy ◽  
Predicted Values ◽  
Experimental Values ◽  
Activity Interaction Parameter ◽  
Good Agreement

It is important to know the activity interaction parameters between components in melts in the process of metallurgy. However, it’s considerably difficult to measure them experimentally, relying still to a large extent on theoretical calculations. In this paper, the first-order activity interaction parameter (esj) of j on sulphur in Fe-based melts at 1873 K is investigated by a calculation model established by combining the Miedema model and Toop-Hillert geometric model as well as considering excess entropy and mixing enthalpy. We consider two strategies, with or without using excess entropy in the calculations. Our results show that: (1) the predicted values are in good agreement with those recommended by Japan Society for Promotion of Science (JSPS); and (2) the agreement is even better when excess entropy is considered in the calculations. In addition, the deviations of our theoretical results from experimental values eS(exp)j-eS(cal)j depend on the element j’s locations in the periodic table.

The β+ Decay of 234Np and Other Isospin-Forbidden 0+→ 0+ Fermi Transitions

1984 ◽  
Vol 39 (12) ◽  
pp. 1168-1171
Author(s):  
C. T. Yap ◽  
E. L. Saw
Keyword(s):  
Nuclear Matrix ◽  
Coulomb Potential ◽  
Deformation Parameter ◽  
Theoretical Calculations ◽  
Wave Functions ◽  
Matrix Elements ◽  
Β Decay ◽  
A Value ◽  
Experimental Values ◽  
Good Agreement

Although experimental values of the Fermi nuclear matrix elements vary widely from about 1 × 10-3 to 40 × 10-3 for isospin-forbidden 0+→0+ β transitions, theoretical calculations using the Coulomb potential and Nilsson wave functions yielded values of MF in reasonably good agreement, except that of 234Np. However, our calculation of MF for this decay as a function of the deformation parameter β yielded a value of MF in good agreement with experiment for values of β between 0.1 and 0.2.

Pb-free solders: Predicting of some physicochemical properties of Ag–Cu–Sn material at different temperatures

2016 ◽  
Vol 15 (07) ◽  
pp. 1650062 ◽  
Author(s):  
Rachida M’chaar ◽  
Mouloud El Moudane ◽  
Abdelaziz Sabbar ◽  
Ahmed Ghanimi
Keyword(s):  
Surface Tension ◽  
Physicochemical Properties ◽  
Molar Volume ◽  
The Other ◽  
Ternary Alloys ◽  
Other Hand ◽  
Different Temperatures ◽  
Experimental Values ◽  
Increasing Temperature ◽  
Good Agreement

In this paper, the surface tension, molar volume and density of liquid Ag–Cu–Sn alloys have been calculated using Kohler, Muggianu, Toop, and Hillert models. In addition, the surface tension and viscosity of the Ag–Cu–Sn ternary alloys at different temperatures have been predicted on the basis of Guggenheim and Seetharaman–Sichen equations, respectively. The results show that density and viscosity decrease with increasing tin and increasing temperature for the all studied models. While the surface tension shows a different tendency, especially for the Kohler and Muggianu symmetric models. On the other hand, the molar volume increases with increase of temperature and tin compositions. The calculated values of surface tension and density of Ag–Cu–Sn alloys are compared with the available experimental values and a good agreement was observed.

Structural, Thermodynamics and Dynamics Properties of Fe-Ni Melts with Different EAM Models

2013 ◽  
Vol 750-752 ◽  
pp. 579-582
Author(s):  
Teng Fang ◽  
Li Wang ◽  
Yu Qi
Keyword(s):  
Diffusion Coefficients ◽  
Md Simulation ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Ni Alloy ◽  
Mixing Behavior ◽  
Thermodynamics And Dynamics ◽  
Experimental Values ◽  
And Diffusion ◽  
Good Agreement

Molecular dynamics (MD) simulation has been performed to explore the microstructure, thermodynamics and dynamics properties of liquid Fe-Ni alloy based upon two different embedded atom method (EAM) models. The calculated PCFs with two EAM models are good agreement with the experimental values. While the calculated Scc (q) of Bhatia-Thornton (B-T) structure factor (SF) shows different behavior: a sharp increasing and a small one at lower q from G. Bonnys model and Zhous model respectively. The mixing of enthalpy with G. Bonnys EAM is positive in the whole concentration range. While the different mixing behavior with a slightly negative mixing of enthalpy based on Zhous model, which is consistent with the experimental results, is observed. Density and diffusion coefficients of liquid Fe-Ni as a function of composition show the same tendency based on both G. Bonnys model and Zhous model. In this work, Fe-Ni melts show different mixing behavior based on the two different EAM models.

First Principle Study of Ti50Al50 Alloys

2018 ◽  
Vol 770 ◽  
pp. 224-229
Author(s):  
Rosinah Modiba ◽  
Hasani Chauke ◽  
Phuti Ngoepe
Keyword(s):  
Experimental Data ◽  
High Temperatures ◽  
Elastic Constants ◽  
Martensitic Phase ◽  
First Principle ◽  
Lattice Constants ◽  
B2 Phase ◽  
Experimental Values ◽  
Good Agreement

The study on the Ti-based materials and its application has been the interest of many research industries. These alloys are known to have an ordered B2 phase at high temperatures and transform to a stable low B19 martensitic phase. First principle approach has been used to study L10, B32, B2 and B19 Ti50Al50alloys and the results compared well with the available experimental data. The equilibrium lattice constants are in good agreement with the experimental values (within 3% agreement). Furthermore, the elastic constants of these alloys are calculated, and revealed stability for L10and B19 structures, while B2 and B32 gave C′<0 (condition of instability).

Estimation of Thermal Shock Resistance by Infrared Radiation Heating and Water Flow Cooling Techniques

2006 ◽  
Vol 317-318 ◽  
pp. 339-342
Author(s):  
Sawao Honda ◽  
Hiroaki Tanaka ◽  
Hideo Awaji
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Rapid Heating ◽  
Ceramic Materials ◽  
Shock Resistance ◽  
Testing Techniques ◽  
Experimental Values ◽  
Definition Of ◽  
Increasing Temperature ◽  
Good Agreement

Thermal shock is a mechanism often leading to failure of ceramic materials that may occur during rapid heating or cooling. These tests were performed in order to compare the thermal shock resistance of ceramic materials by cooling with that of the heating method and hence to evaluate parameters such as thermal shock strength (R1c) and thermal shock fracture toughness (R2c). During the present study, thermal shock resistance of alumina and mullite ceramics was estimated experimentally and theoretically using the thermal shock parameters. The critical thermal stress at the onset of thermal shock fracture was calculated using fracture time, which is measured by an acoustic emission. Results show that thermal shock parameters of alumina specimens decreased with increasing temperature of fracture point. This effect can be attributed to the temperature dependence of the thermal properties. The experimental values of thermal shock parameters evaluated by IRH and WFC techniques were in good agreement at the temperature of fracture point. The thermal shock parameters enabled the definition of a unified thermal shock resistance of ceramics, which is independent of the nature of the testing techniques.

First Principles Study of Electronic and Elastic Properties of AlY

2014 ◽  
Vol 1047 ◽  
pp. 45-50
Author(s):  
Mani Shugani ◽  
Mahendra Aynyas ◽  
S.P. Sanyal
Keyword(s):  
Elastic Properties ◽  
Elastic Constants ◽  
Ground State ◽  
Full Potential ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Lattice Constants ◽  
Ground State Properties ◽  
Experimental Values ◽  
Good Agreement

We have used full potential linear augmented plane wave method within thegeneralized gradient approximation to investigate the structural, electronic and elastic properties of the AlY. The ground state properties are determined for the AlY. The calculated ground state properties such as lattice constants, bulk modulus and elastic constants agree well with the experimental values. From band structure curves it is found that AlY is metallic in nature. The elastic constants are in good agreement with previous theoretical and experimental results.

Studies of energy levels, hyperfine structure, and transition probabilities for neutral silicon

2016 ◽  
Vol 94 (4) ◽  
pp. 359-364 ◽  
Author(s):  
Miao Wu ◽  
Guojie Bian ◽  
Xiangfu Li ◽  
Min Xu ◽  
Quanping Fan ◽  
...  
Keyword(s):  
Hyperfine Structure ◽  
Quantum Electrodynamics ◽  
Transition Probabilities ◽  
Theoretical Calculations ◽  
Energy Levels ◽  
Structure Constant ◽  
Hartree Fock ◽  
Hyperfine Structure Constant ◽  
Experimental Values ◽  
Good Agreement

The multi-configuration Dirac–Hartree–Fock method and active space approach are used to investigate the energy levels, hyperfine structure constants, and transition probabilities of a neutral silicon atom. The contributions of Breit interactions and quantum electrodynamics correction are considered. Compared with other theoretical and experimental values of energy levels, our values are in good agreement; the discrepancies of the majority of energy levels calculated are within 1% of experimental values, and the energy levels calculated are very close to other theoretical values. The number of energy levels we considered is larger than that of any other theoretical calculations. The values of the hyperfine structure constant A of the radioactive 29Si atom that we calculated are in good agreement with experimental values. From these results we can predict the hyperfine structure constant A of other states of 29Si where no other theoretical results are available. The transition probabilities of neutral silicon have also been calculated and discussed.

Equation of State, Nonlinear Elastic Response, and Anharmonic Properties of Diamond-Cubic Silicon and Germanium: First-Principles Investigation

2015 ◽  
Vol 70 (6) ◽  
pp. 403-412 ◽  
Author(s):  
Chenju Wang ◽  
Jianbing Gu ◽  
Xiaoyu Kuang ◽  
Shikai Xiang
Keyword(s):  
Elastic Constants ◽  
Theoretical Calculations ◽  
Theoretical Data ◽  
Elastic Response ◽  
Experimental Result ◽  
Elastic Behaviour ◽  
Third Order Elastic Constants ◽  
Silicon And Germanium ◽  
Nonlinear Elastic ◽  
Good Agreement

AbstractNonlinear elastic properties of diamond-cubic silicon and germanium have not been investigated sufficiently to date. Knowledge of these properties not only can help us to understand nonlinear mechanical effects but also can assist us to have an insight into the related anharmonic properties, so we investigate the nonlinear elastic behaviour of single silicon and germanium by calculating their second- and third-order elastic constants. All the results of the elastic constants show good agreement with the available experimental data and other theoretical calculations. Such a phenomenon indicates that the present values of the elastic constants are accurate and can be used to further study the related anharmonic properties. Subsequently, the anharmonic properties such as the pressure derivatives of the second-order elastic constants, Grüneisen constants of long-wavelength acoustic modes, and ultrasonic nonlinear parameters are explored. All the anharmonic properties of silicon calculated in the present work also show good agreement with the existing experimental results; this consistency not only reveals that the calculation method of the anharmonic properties is feasible but also illuminates that the anharmonic properties obtained in the present work are reliable. For the anharmonic properties of germanium, since there are no experimental result and other theoretical data till now, we hope that the anharmonic properties of germanium first offered in this work would serve as a reference for future studies.

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