The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Yasemin Oztekin Ciftci - One of the best experts on this subject based on the ideXlab platform.
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Vibrational properties of Re2N and Re3N compounds
Solid State Communications, 2011Co-Authors: Engin Deligoz, Kemal Colakoglu, Havva Bogaz Ozisik, Yasemin Oztekin CiftciAbstract:Abstract Using first-principles calculations, we have studied the structural, lattice dynamical and thermodynamical properties of the recently synthesized Re2N and Re3N compounds. The generalized gradient approximation is used to model exchange–correlation effects. The phonon dispersion curves are derived using the direct method. The calculated equilibrium lattice parameters are in overall agreement with the available experimental and theoretical results. The present phonon dispersion results show that both compounds are dynamically stable for the structures considered. The temperature-dependent behavior of thermodynamical properties, such as free energy, Entropy, Heat capacity, and internal energy, is also presented.
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Lattice dynamical and thermodynamical properties of HfB2 and TaB2 compounds
Computational Materials Science, 2010Co-Authors: Engin Deligoz, Kemal Colakoglu, Yasemin Oztekin CiftciAbstract:Abstract We have investigated the structural parameters (the lattice constants and bond length) and phonon dispersion relations in XB 2 (X = Hf, Ta) compounds using the first-principles total energy calculations. The generalized gradient approximations are used to model exchange–correlation effects. Our secondary results on the temperature-dependent behavior of thermodynamical properties such as Entropy, Heat capacity, internal energy, and free energy are also presented for the same compounds. The obtained results are in good agreement with the available experimental and other theoretical data.
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Phonon dispersion and thermodynamical properties in ZrB2, NbB2, and MoB2
Solid State Communications, 2009Co-Authors: Engin Deligoz, Kemal Colakoglu, Yasemin Oztekin CiftciAbstract:Abstract The structural and lattice dynamical calculations are performed on ZrB2, NbB2, and MoB2 compounds using the first-principles of total energy calculations. Generalized gradient approximations (GGA) are used to model exchange-correlation effects. Structural results of these calculations are consistent with past experimental data and other theoretical findings. Our lattice dynamical results regarding phonon dispersion curves and temperature-dependent behavior of thermodynamical properties (Entropy, Heat capacity, internal energy, and free energy) contribute to the existing literature on these compounds.
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Lattice dynamical properties of ScB2, TiB2, and V B2 compounds
Solid State Communications, 2009Co-Authors: Engin Deligoz, Kemal Colakoglu, Yasemin Oztekin CiftciAbstract:Abstract We have investigated the structural and lattice dynamical properties of XB2(X=Sc,V,Ti) by using first-principles total energy calculations. Specifically, the lattice parameters (a, c) of the stable phase, the bond lengths of X–B and B–B atoms, phonon dispersion curves and the corresponding density of states, and some thermodynamical quantities such as internal energy, Entropy, Heat capacity, and their temperature-dependent behaviours, are presented. The obtained results for structural parameters are in good agreement with the available experimental and other theoretical studies.
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A first-principles study on the structural, elastic, vibrational, and thermodynamical properties of BaX (X=S, Se, and Te)
Journal of Physics and Chemistry of Solids, 2009Co-Authors: E. Tuncel, Kemal Colakoglu, Engin Deligoz, Yasemin Oztekin CiftciAbstract:Ab-initio calculations based on norm-conserving pseudopotentials and density functional theory (DFT) have been performed to investigate the structural, elastic, thermodynamic, and lattice dynamical (phonon dispersion curves) properties of BaX in rock-salt (B1) and CsCl (B2) structures. The results support the experimental and theoretical data in the existing literature. Findings are also presented for the temperature-dependent behaviors of some thermodynamic properties such as Entropy, Heat capacity, internal energy, and free energy for the same compounds in the B1 phase.
Anatoliy I Fisenko - One of the best experts on this subject based on the ideXlab platform.
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generalized wien s displacement law in determining the true temperature of text zrb _ 2 sic based ultrahigh temperature ceramic thermodynamics of thermal radiation
International Journal of Thermophysics, 2013Co-Authors: Anatoliy I Fisenko, Vladimir F LembergAbstract:The temperature dependence of the generalized Wien displacement law is investigated. For determining the true temperature of a \(\text{ ZrB }_{2}\)–SiC-based ultrahigh-temperature ceramic, the experimental values of the position of the maximum of the spectral density power are needed. Thermodynamics of the thermal radiation of \(\text{ ZrB }_{2}\)–SiC is constructed by using the temperature dependence of the generalized Stefan–Boltzmann law. The calculated values of the normal total emissivity for \(\text{ ZrB }_{2}\)–SiC at different temperatures are in good agreement with experimental data. The total radiation power emitted from a surface of \(\text{ ZrB }_{2}\)–SiC specimens at different temperatures is calculated. The temperature dependences of the Helmholtz free energy, Entropy, Heat capacity at constant volume, pressure, enthalpy, and internal energy of the thermal radiation of \(\text{ ZrB }_{2}\)–SiC are obtained. For determining the true temperature, experimental values of either the normal total emissivity or the normal total energy density are needed. The uncertainty in the determination of the true temperature is no greater than 1 %. A new universality class of bodies with a new relationship between the temperature \(T\) and the position of the spectral energy density maximum is established.
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Generalized Wien’s Displacement Law in Determining the True Temperature of $$\text{ ZrB }_{2}$$
International Journal of Thermophysics, 2013Co-Authors: Anatoliy I Fisenko, Vladimir LembergAbstract:The temperature dependence of the generalized Wien displacement law is investigated. For determining the true temperature of a $$\text{ ZrB }_{2}$$ ZrB 2 –SiC-based ultrahigh-temperature ceramic, the experimental values of the position of the maximum of the spectral density power are needed. Thermodynamics of the thermal radiation of $$\text{ ZrB }_{2}$$ ZrB 2 –SiC is constructed by using the temperature dependence of the generalized Stefan–Boltzmann law. The calculated values of the normal total emissivity for $$\text{ ZrB }_{2}$$ ZrB 2 –SiC at different temperatures are in good agreement with experimental data. The total radiation power emitted from a surface of $$\text{ ZrB }_{2}$$ ZrB 2 –SiC specimens at different temperatures is calculated. The temperature dependences of the Helmholtz free energy, Entropy, Heat capacity at constant volume, pressure, enthalpy, and internal energy of the thermal radiation of $$\text{ ZrB }_{2}$$ ZrB 2 –SiC are obtained. For determining the true temperature, experimental values of either the normal total emissivity or the normal total energy density are needed. The uncertainty in the determination of the true temperature is no greater than 1 %. A new universality class of bodies with a new relationship between the temperature $$T$$ T and the position of the spectral energy density maximum is established.
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Radiative Properties of Stoichiometric Hafnium, Titanium, and Zirconium Carbides: Thermodynamics of Thermal Radiation
International Journal of Thermophysics, 2012Co-Authors: Anatoliy I Fisenko, Vladimir LembergAbstract:The true temperatures of the thermal radiation of stoichiometric hafnium, titanium, and zirconium carbides are defined from the generalized Wien displacement law. It is shown that Wien’s displacement law for the investigated stoichiometric carbides decreases linearly with increasing temperature. The uncertainties in the determination of the true temperature are no greater than 1 %. For determining the true temperature of stoichiometric carbides, the experimental values of the position of the maximum of the spectral density power are needed. By extrapolating the generalized Wien displacement laws in the ultra-high-temperature region, the positions of the maximum of the normal energy density of hafnium, titanium, and zirconium carbides at melting temperatures are obtained. Thermodynamics of thermal radiation of stoichiometric carbides is constructed by using the temperature dependences of the generalized Stefan–Boltzmann law. The calculated values of the normal total emissivity for the investigated carbides at different temperatures are in good agreement with experimental data. For determining the true temperatures of the thermal radiation of stoichiometric carbides, experimental values of either the normal total emissivity or the normal total energy density are needed. The temperature dependences of the Helmholtz free energy, Entropy, Heat capacity at constant volume, pressure, enthalpy, and internal energy of the thermal radiation of stoichiometric carbides at high temperature are obtained. It is shown that thermodynamic function values increase with increasing temperature as a power law.
Vladimir Lemberg - One of the best experts on this subject based on the ideXlab platform.
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Generalized Wien’s Displacement Law in Determining the True Temperature of $$\text{ ZrB }_{2}$$
International Journal of Thermophysics, 2013Co-Authors: Anatoliy I Fisenko, Vladimir LembergAbstract:The temperature dependence of the generalized Wien displacement law is investigated. For determining the true temperature of a $$\text{ ZrB }_{2}$$ ZrB 2 –SiC-based ultrahigh-temperature ceramic, the experimental values of the position of the maximum of the spectral density power are needed. Thermodynamics of the thermal radiation of $$\text{ ZrB }_{2}$$ ZrB 2 –SiC is constructed by using the temperature dependence of the generalized Stefan–Boltzmann law. The calculated values of the normal total emissivity for $$\text{ ZrB }_{2}$$ ZrB 2 –SiC at different temperatures are in good agreement with experimental data. The total radiation power emitted from a surface of $$\text{ ZrB }_{2}$$ ZrB 2 –SiC specimens at different temperatures is calculated. The temperature dependences of the Helmholtz free energy, Entropy, Heat capacity at constant volume, pressure, enthalpy, and internal energy of the thermal radiation of $$\text{ ZrB }_{2}$$ ZrB 2 –SiC are obtained. For determining the true temperature, experimental values of either the normal total emissivity or the normal total energy density are needed. The uncertainty in the determination of the true temperature is no greater than 1 %. A new universality class of bodies with a new relationship between the temperature $$T$$ T and the position of the spectral energy density maximum is established.
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Radiative Properties of Stoichiometric Hafnium, Titanium, and Zirconium Carbides: Thermodynamics of Thermal Radiation
International Journal of Thermophysics, 2012Co-Authors: Anatoliy I Fisenko, Vladimir LembergAbstract:The true temperatures of the thermal radiation of stoichiometric hafnium, titanium, and zirconium carbides are defined from the generalized Wien displacement law. It is shown that Wien’s displacement law for the investigated stoichiometric carbides decreases linearly with increasing temperature. The uncertainties in the determination of the true temperature are no greater than 1 %. For determining the true temperature of stoichiometric carbides, the experimental values of the position of the maximum of the spectral density power are needed. By extrapolating the generalized Wien displacement laws in the ultra-high-temperature region, the positions of the maximum of the normal energy density of hafnium, titanium, and zirconium carbides at melting temperatures are obtained. Thermodynamics of thermal radiation of stoichiometric carbides is constructed by using the temperature dependences of the generalized Stefan–Boltzmann law. The calculated values of the normal total emissivity for the investigated carbides at different temperatures are in good agreement with experimental data. For determining the true temperatures of the thermal radiation of stoichiometric carbides, experimental values of either the normal total emissivity or the normal total energy density are needed. The temperature dependences of the Helmholtz free energy, Entropy, Heat capacity at constant volume, pressure, enthalpy, and internal energy of the thermal radiation of stoichiometric carbides at high temperature are obtained. It is shown that thermodynamic function values increase with increasing temperature as a power law.
Engin Deligoz - One of the best experts on this subject based on the ideXlab platform.
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Vibrational properties of Re2N and Re3N compounds
Solid State Communications, 2011Co-Authors: Engin Deligoz, Kemal Colakoglu, Havva Bogaz Ozisik, Yasemin Oztekin CiftciAbstract:Abstract Using first-principles calculations, we have studied the structural, lattice dynamical and thermodynamical properties of the recently synthesized Re2N and Re3N compounds. The generalized gradient approximation is used to model exchange–correlation effects. The phonon dispersion curves are derived using the direct method. The calculated equilibrium lattice parameters are in overall agreement with the available experimental and theoretical results. The present phonon dispersion results show that both compounds are dynamically stable for the structures considered. The temperature-dependent behavior of thermodynamical properties, such as free energy, Entropy, Heat capacity, and internal energy, is also presented.
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Lattice dynamical and thermodynamical properties of HfB2 and TaB2 compounds
Computational Materials Science, 2010Co-Authors: Engin Deligoz, Kemal Colakoglu, Yasemin Oztekin CiftciAbstract:Abstract We have investigated the structural parameters (the lattice constants and bond length) and phonon dispersion relations in XB 2 (X = Hf, Ta) compounds using the first-principles total energy calculations. The generalized gradient approximations are used to model exchange–correlation effects. Our secondary results on the temperature-dependent behavior of thermodynamical properties such as Entropy, Heat capacity, internal energy, and free energy are also presented for the same compounds. The obtained results are in good agreement with the available experimental and other theoretical data.
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Phonon dispersion and thermodynamical properties in ZrB2, NbB2, and MoB2
Solid State Communications, 2009Co-Authors: Engin Deligoz, Kemal Colakoglu, Yasemin Oztekin CiftciAbstract:Abstract The structural and lattice dynamical calculations are performed on ZrB2, NbB2, and MoB2 compounds using the first-principles of total energy calculations. Generalized gradient approximations (GGA) are used to model exchange-correlation effects. Structural results of these calculations are consistent with past experimental data and other theoretical findings. Our lattice dynamical results regarding phonon dispersion curves and temperature-dependent behavior of thermodynamical properties (Entropy, Heat capacity, internal energy, and free energy) contribute to the existing literature on these compounds.
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Lattice dynamical properties of ScB2, TiB2, and V B2 compounds
Solid State Communications, 2009Co-Authors: Engin Deligoz, Kemal Colakoglu, Yasemin Oztekin CiftciAbstract:Abstract We have investigated the structural and lattice dynamical properties of XB2(X=Sc,V,Ti) by using first-principles total energy calculations. Specifically, the lattice parameters (a, c) of the stable phase, the bond lengths of X–B and B–B atoms, phonon dispersion curves and the corresponding density of states, and some thermodynamical quantities such as internal energy, Entropy, Heat capacity, and their temperature-dependent behaviours, are presented. The obtained results for structural parameters are in good agreement with the available experimental and other theoretical studies.
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A first-principles study on the structural, elastic, vibrational, and thermodynamical properties of BaX (X=S, Se, and Te)
Journal of Physics and Chemistry of Solids, 2009Co-Authors: E. Tuncel, Kemal Colakoglu, Engin Deligoz, Yasemin Oztekin CiftciAbstract:Ab-initio calculations based on norm-conserving pseudopotentials and density functional theory (DFT) have been performed to investigate the structural, elastic, thermodynamic, and lattice dynamical (phonon dispersion curves) properties of BaX in rock-salt (B1) and CsCl (B2) structures. The results support the experimental and theoretical data in the existing literature. Findings are also presented for the temperature-dependent behaviors of some thermodynamic properties such as Entropy, Heat capacity, internal energy, and free energy for the same compounds in the B1 phase.
Kemal Colakoglu - One of the best experts on this subject based on the ideXlab platform.
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Vibrational properties of Re2N and Re3N compounds
Solid State Communications, 2011Co-Authors: Engin Deligoz, Kemal Colakoglu, Havva Bogaz Ozisik, Yasemin Oztekin CiftciAbstract:Abstract Using first-principles calculations, we have studied the structural, lattice dynamical and thermodynamical properties of the recently synthesized Re2N and Re3N compounds. The generalized gradient approximation is used to model exchange–correlation effects. The phonon dispersion curves are derived using the direct method. The calculated equilibrium lattice parameters are in overall agreement with the available experimental and theoretical results. The present phonon dispersion results show that both compounds are dynamically stable for the structures considered. The temperature-dependent behavior of thermodynamical properties, such as free energy, Entropy, Heat capacity, and internal energy, is also presented.
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Lattice dynamical and thermodynamical properties of HfB2 and TaB2 compounds
Computational Materials Science, 2010Co-Authors: Engin Deligoz, Kemal Colakoglu, Yasemin Oztekin CiftciAbstract:Abstract We have investigated the structural parameters (the lattice constants and bond length) and phonon dispersion relations in XB 2 (X = Hf, Ta) compounds using the first-principles total energy calculations. The generalized gradient approximations are used to model exchange–correlation effects. Our secondary results on the temperature-dependent behavior of thermodynamical properties such as Entropy, Heat capacity, internal energy, and free energy are also presented for the same compounds. The obtained results are in good agreement with the available experimental and other theoretical data.
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Phonon dispersion and thermodynamical properties in ZrB2, NbB2, and MoB2
Solid State Communications, 2009Co-Authors: Engin Deligoz, Kemal Colakoglu, Yasemin Oztekin CiftciAbstract:Abstract The structural and lattice dynamical calculations are performed on ZrB2, NbB2, and MoB2 compounds using the first-principles of total energy calculations. Generalized gradient approximations (GGA) are used to model exchange-correlation effects. Structural results of these calculations are consistent with past experimental data and other theoretical findings. Our lattice dynamical results regarding phonon dispersion curves and temperature-dependent behavior of thermodynamical properties (Entropy, Heat capacity, internal energy, and free energy) contribute to the existing literature on these compounds.
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Lattice dynamical properties of ScB2, TiB2, and V B2 compounds
Solid State Communications, 2009Co-Authors: Engin Deligoz, Kemal Colakoglu, Yasemin Oztekin CiftciAbstract:Abstract We have investigated the structural and lattice dynamical properties of XB2(X=Sc,V,Ti) by using first-principles total energy calculations. Specifically, the lattice parameters (a, c) of the stable phase, the bond lengths of X–B and B–B atoms, phonon dispersion curves and the corresponding density of states, and some thermodynamical quantities such as internal energy, Entropy, Heat capacity, and their temperature-dependent behaviours, are presented. The obtained results for structural parameters are in good agreement with the available experimental and other theoretical studies.
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A first-principles study on the structural, elastic, vibrational, and thermodynamical properties of BaX (X=S, Se, and Te)
Journal of Physics and Chemistry of Solids, 2009Co-Authors: E. Tuncel, Kemal Colakoglu, Engin Deligoz, Yasemin Oztekin CiftciAbstract:Ab-initio calculations based on norm-conserving pseudopotentials and density functional theory (DFT) have been performed to investigate the structural, elastic, thermodynamic, and lattice dynamical (phonon dispersion curves) properties of BaX in rock-salt (B1) and CsCl (B2) structures. The results support the experimental and theoretical data in the existing literature. Findings are also presented for the temperature-dependent behaviors of some thermodynamic properties such as Entropy, Heat capacity, internal energy, and free energy for the same compounds in the B1 phase.