In the present work, we have calculated the thermodynamic properties of an asymmetrical Gaussian potential quantum dot under external electric field. To this end, we have solved the Schr�dinger equation and have obtained the energy levels and wave functions, analytically. According to the obtained eigenvalues, we have calculated the partition function of the system by the Poisson summation formalism. Afterward, we have deduced some thermodynamic properties such as mean energy, entropy, specific heat and free energy under the application of an external electric field using the canonical ensemble approach. These thermodynamic properties for an asymmetrical Gaussian potential GaAs quantum dot have been discussed in detail.
{"title":"Thermodynamic properties of GaAs quantum dot confined by asymmetric Gaussian potential","authors":"A. Ghanbari, Raziyeh Birooni","doi":"10.32908/hthp.v51.1251","DOIUrl":"https://doi.org/10.32908/hthp.v51.1251","url":null,"abstract":"In the present work, we have calculated the thermodynamic properties of an asymmetrical Gaussian potential quantum dot under external electric field. To this end, we have solved the Schr�dinger equation and have obtained the energy levels and wave functions, analytically. According to the obtained eigenvalues, we have calculated the partition function of the system by the Poisson summation formalism. Afterward, we have deduced some thermodynamic properties such as mean energy, entropy, specific heat and free energy under the application of an external electric field using the canonical ensemble approach. These thermodynamic properties for an asymmetrical Gaussian potential GaAs quantum dot have been discussed in detail.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69443079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper discusses density and molar volume of liquid alloys of iron with C, B, Si, P, Cu, Al, Ni, Cr and Mn. Liquid alloys of iron with other metals are considered as substitutional solutions using the hard-sphere model. Deviations of molar volumes of Fe-Cu and Fe-Al alloys from the ideal solutions were analysed using relationship between excess volume and entropy. Alloys of iron with Ni, Cr and Mn are close to the ideal solutions. Calculated volumes are in agreement with experimental data. Alloys of Fe with C, B, Si and P are considered as interstitial solutions using P. Gaskell�s model developed for amorphous alloys of transition metals with metalloids. Calculated partial molar volumes of C, B, Si and P in dilute binary solutions at 1823 K are (cm3/mol): 1.59, 3.37, 7.06 and 6.26 respectively. The model correctly describes the liquid alloys of iron with metalloids as interstitial solutions.
{"title":"Density and molar volumes of liquid alloys of iron with C, B, Si, P, Cu, Al, Ni, Cr and Mn","authors":"O. Ostrovski","doi":"10.32908/hthp.v51.1255","DOIUrl":"https://doi.org/10.32908/hthp.v51.1255","url":null,"abstract":"The paper discusses density and molar volume of liquid alloys of iron with C, B, Si, P, Cu, Al, Ni, Cr and Mn. Liquid alloys of iron with other metals are considered as substitutional solutions using the hard-sphere model. Deviations of molar volumes of Fe-Cu and Fe-Al alloys from the ideal solutions were analysed using relationship between excess volume and entropy. Alloys of iron with Ni, Cr and Mn are close to the ideal solutions. Calculated volumes are in agreement with experimental data. Alloys of Fe with C, B, Si and P are considered as interstitial solutions using P. Gaskell�s model developed for amorphous alloys of transition metals with metalloids. Calculated partial molar volumes of C, B, Si and P in dilute binary solutions at 1823 K are (cm3/mol): 1.59, 3.37, 7.06 and 6.26 respectively. The model correctly describes the liquid alloys of iron with metalloids as interstitial solutions.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69443104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A critical analysis of size and shape dependence properties of different type of nanomaterials is presented using a simple theory of equation of state (EOS) and bulk modulus. It is observed that compression behavior of nanomaterials depends on size and shape in addition to the applied pressure. To confirm the situation we have considered different type of nanomaterials. The model predictions are compared with the available experimental data. A good agreement between theory and experiments demonstrate the validity of model proposed for nanomaterials. Some results have also been reported in absence of experimental data to help the researcher engaged in the experimental studies of nanomaterials. Due to the simplicity and applicability of the model, it may be used to understand other properties of nanomaterials under varying physical conditions.
{"title":"Size and Shape dependence equation of state and bulk modulus for nanomaterials","authors":"Sonia Sharma, Munish Kumar","doi":"10.32908/hthp.v51.1183","DOIUrl":"https://doi.org/10.32908/hthp.v51.1183","url":null,"abstract":"A critical analysis of size and shape dependence properties of different type of nanomaterials is presented using a simple theory of equation of state (EOS) and bulk modulus. It is observed that compression behavior of nanomaterials depends on size and shape in addition to the applied pressure. To confirm the situation we have considered different type of nanomaterials. The model predictions are compared with the available experimental data. A good agreement between theory and experiments demonstrate the validity of model proposed for nanomaterials. Some results have also been reported in absence of experimental data to help the researcher engaged in the experimental studies of nanomaterials. Due to the simplicity and applicability of the model, it may be used to understand other properties of nanomaterials under varying physical conditions.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Leila Benbia, Saida Fedali, C. Bougriou, H. Madani
The current study concerns the use of azeotropic mixtures in single-stage vapor compression refrigeration system configurations to determine the effect of entrainment ratio on the coefficient of performance. Three singlestage vapor compression refrigeration system configurations are used. The effects of condenser and evaporator temperatures on the single-stage refrigeration system are investigated. The used azeotropic mixtures are: R1234yf + R290, R1234yf + R152a, R1234yf + R600a, R134a + R290, R134a + R600a and R1270 + R134a. It is shown that the simulations results are in good agreement with the literature. The R1234yf + R290 mixture in refrigeration cycle give the highest coefficient of performance and entrainment ratio. The coefficient of performance (COP) increases with increasing of entrainment ratio.
{"title":"Influence of azeotropic binary mixtures on single-stage refrigeration system performance","authors":"Leila Benbia, Saida Fedali, C. Bougriou, H. Madani","doi":"10.32908/hthp.v51.1185","DOIUrl":"https://doi.org/10.32908/hthp.v51.1185","url":null,"abstract":"The current study concerns the use of azeotropic mixtures in single-stage vapor compression refrigeration system configurations to determine the effect of entrainment ratio on the coefficient of performance. Three singlestage vapor compression refrigeration system configurations are used. The effects of condenser and evaporator temperatures on the single-stage refrigeration system are investigated. The used azeotropic mixtures are: R1234yf + R290, R1234yf + R152a, R1234yf + R600a, R134a + R290, R134a + R600a and R1270 + R134a. It is shown that the simulations results are in good agreement with the literature. The R1234yf + R290 mixture in refrigeration cycle give the highest coefficient of performance and entrainment ratio. The coefficient of performance (COP) increases with increasing of entrainment ratio.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The thermodynamic and elastic theory of B2 substitutional alloy AB and B2 interstitial alloy AB under temperature and pressure are derived by the statistical moment method. In the case of zero concentration of substitutional atoms B and interstitial atoms B, we obtain the thermodynamic and elastic theory of main metal A with simple cubic structure. Our numerical calculations according to the model of interstitial alloy for B2-Fe99Si1 and the model of substitutional alloy for B2-Fe50Si50 in the temperature interval from zero to 1500 K and the pressure interval from zero to 160 GPa are in relatively good with experiments and other calculations.
{"title":"Study on thermodynamic and elastic properties of B2-FeSi by statistical moment method","authors":"N. Hoc, Nguyen Duc Hien","doi":"10.32908/hthp.v51.1231","DOIUrl":"https://doi.org/10.32908/hthp.v51.1231","url":null,"abstract":"The thermodynamic and elastic theory of B2 substitutional alloy AB and B2 interstitial alloy AB under temperature and pressure are derived by the statistical moment method. In the case of zero concentration of substitutional atoms B and interstitial atoms B, we obtain the thermodynamic and elastic theory of main metal A with simple cubic structure. Our numerical calculations according to the model of interstitial alloy for B2-Fe99Si1 and the model of substitutional alloy for B2-Fe50Si50 in the temperature interval from zero to 1500 K and the pressure interval from zero to 160 GPa are in relatively good with experiments and other calculations.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Saad Tariq, A. Mubarak, Ihab A Abdel Latif, M. Saleem, B. Kanwal, M. Jamil
In this article, we have used density functional theory to investigate the pressure dependent structural, elastic, thermal and electronic properties of LaMO3 (M = Al, Ga, Ti and V) compounds. Optimized structural attributes suggest all compounds are thermodynamically stable based on enthalpy of formation, ground state optimizations and tolerance factor. Moreover, elastic stability criteria also portray results in support of the structural stability of compounds. In electronic properties, the density of states plot suggests anti-ferromagnetic attributes. While transition in the band gap from indirect to direct is observed at 50 GPa for all studied compounds except for LaGaO3. In mechanical properties, stiffness, super-plasticity and moduli of elasticity of the studied compounds observed to increase linearly with pressure. The compound LaTiO3 has shown plausible piezoelectricity under pressure. We expect that studied compounds will fulfil requirements of high pressure optoelectronic sensors and devices.
{"title":"Bandgap tuning with pressure for plausible piezoelectric and electronic applications of Lanthanum oxides LaMO3 (M = Al, Ga, Ti and V)","authors":"Saad Tariq, A. Mubarak, Ihab A Abdel Latif, M. Saleem, B. Kanwal, M. Jamil","doi":"10.32908/hthp.v51.1129","DOIUrl":"https://doi.org/10.32908/hthp.v51.1129","url":null,"abstract":"In this article, we have used density functional theory to investigate the pressure dependent structural, elastic, thermal and electronic properties of LaMO3 (M = Al, Ga, Ti and V) compounds. Optimized structural attributes suggest all compounds are thermodynamically stable based on enthalpy of formation, ground state optimizations and tolerance factor. Moreover, elastic stability criteria also portray results in support of the structural stability of compounds. In electronic properties, the density of states plot suggests anti-ferromagnetic attributes. While transition in the band gap from indirect to direct is observed at 50 GPa for all studied compounds except for LaGaO3. In mechanical properties, stiffness, super-plasticity and moduli of elasticity of the studied compounds observed to increase linearly with pressure. The compound LaTiO3 has shown plausible piezoelectricity under pressure. We expect that studied compounds will fulfil requirements of high pressure optoelectronic sensors and devices.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69443001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present paper the structural, electronic, elastic and thermophysical properties of HfN have been explored by density functional theory (DFT) within the generalized gradient approximation (GGA). The transition of HfN from zinc blende cubic structure(B3) to the simple cubic (B1) structure have been reported considering the hybrid exchange correlation (PBE) practical approach and in agreement with experimental data. The elastic properties is investigated in most stable structure of HfN. Our estimated values of poission ratio and pugh ratio confirm the metallic nature of HfN. The electronic properties which include band structure (BS), density of states (DOS), electron density and fermi surface of HfN are well studied and confirm its metallic nature. Moreover the thermophysical properties viz. Debye temperature, isothermal coefficients, heat capacity, entropy and volume have been studied at high temperature and high pressures for the first time. The thermophysical properties ensures the Debye T3 law and Dulong Petit limit of HfN at high temperatures and high pressures.
{"title":"A first principle studies of structural, electronic, elastic and thermophysical properties of HfN","authors":"A. Gour, M. Sarwan, S. N. Tripati, Sadhna Singh","doi":"10.32908/hthp.v51.1137","DOIUrl":"https://doi.org/10.32908/hthp.v51.1137","url":null,"abstract":"In the present paper the structural, electronic, elastic and thermophysical properties of HfN have been explored by density functional theory (DFT) within the generalized gradient approximation (GGA). The transition of HfN from zinc blende cubic structure(B3) to the simple cubic (B1) structure have been reported considering the hybrid exchange correlation (PBE) practical approach and in agreement with experimental data. The elastic properties is investigated in most stable structure of HfN. Our estimated values of poission ratio and pugh ratio confirm the metallic nature of HfN. The electronic properties which include band structure (BS), density of states (DOS), electron density and fermi surface of HfN are well studied and confirm its metallic nature. Moreover the thermophysical properties viz. Debye temperature, isothermal coefficients, heat capacity, entropy and volume have been studied at high temperature and high pressures for the first time. The thermophysical properties ensures the Debye T3 law and Dulong Petit limit of HfN at high temperatures and high pressures.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69443017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, we have calculated the thermal properties of H2 and O2 diatomic molecules with multi parameter exponential type potential within the framework of the statistical mechanics. In this regard, using the improved energy spectrum, we have determined the vibrational partition function obtained recently via the path integral formalism. Based on obtained partition function, we find thermodynamic properties of diatomic molecules such as Gibbs free energy, enthalpy and specific heat in constant pressure by the Poisson summation formalism. Also, we have validated our results with experimental data and our results show that there is a good agreement between them. Finally, the average absolute deviations of the calculated data from the experimental data are obtained.
{"title":"Thermal properties of diatomic molecules with multi parameter exponential-type potential","authors":"A. Ghanbari, Raziyeh Birooni","doi":"10.32908/hthp.v51.1247","DOIUrl":"https://doi.org/10.32908/hthp.v51.1247","url":null,"abstract":"In this work, we have calculated the thermal properties of H2 and O2 diatomic molecules with multi parameter exponential type potential within the framework of the statistical mechanics. In this regard, using the improved energy spectrum, we have determined the vibrational partition function obtained recently via the path integral formalism. Based on obtained partition function, we find thermodynamic properties of diatomic molecules such as Gibbs free energy, enthalpy and specific heat in constant pressure by the Poisson summation formalism. Also, we have validated our results with experimental data and our results show that there is a good agreement between them. Finally, the average absolute deviations of the calculated data from the experimental data are obtained.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69443421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A theoretical formulism is developed to study the impact of temperature and pressure on nanomaterials. Here Shankar equation of state for solids is extended using an analytic model given by Jiang for nanomaterials. The effect of size, dimension and orientation of nanomaterial on the elastic properties is studied. Bulk modulus is found to decrease as the size of nanomaterials is increased for inward relaxation whereas increase in bulk modulus of nanomaterials with increase in size is found for outward relaxation. Volume expansion coefficient variation is inverse of bulk modulus. The volume decreases as the pressure on the nanomaterials is increased at room temperature, however, volume expansion occurs in nanomaterials with increase in temperature. The nanomaterials of Cu, Ag, Ni, ZnO, SnO2, CeO2, TiO2, ZrO2 and AlN are considered in the present study. The present model results are found in good agreement with the available experimental and theoretically simulated results which justify the present model theory.
{"title":"Effect of size, shape, orientation, pressure and temperature on elastic properties of nanomaterials","authors":"Komal Rawat, M. Goyal","doi":"10.32908/hthp.v51.1009","DOIUrl":"https://doi.org/10.32908/hthp.v51.1009","url":null,"abstract":"A theoretical formulism is developed to study the impact of temperature and pressure on nanomaterials. Here Shankar equation of state for solids is extended using an analytic model given by Jiang for nanomaterials. The effect of size, dimension and orientation of nanomaterial on the elastic properties is studied. Bulk modulus is found to decrease as the size of nanomaterials is increased for inward relaxation whereas increase in bulk modulus of nanomaterials with increase in size is found for outward relaxation. Volume expansion coefficient variation is inverse of bulk modulus. The volume decreases as the pressure on the nanomaterials is increased at room temperature, however, volume expansion occurs in nanomaterials with increase in temperature. The nanomaterials of Cu, Ag, Ni, ZnO, SnO2, CeO2, TiO2, ZrO2 and AlN are considered in the present study. The present model results are found in good agreement with the available experimental and theoretically simulated results which justify the present model theory.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lili Liu, Y. Wen, Shanshan Liu, Jing Xiong, Q. Liao
We present the elastic constants of NiAl and FeAl compounds under high pressure and high temperature by using a first-principles approach. The temperature dependent elastic constants are predicted from the combinations of static volume-dependent elastic constants derived from the first-principles total-energy method within the density-functional theory (DFT). The calculated lattice and elastic constants at ground state are in agreement with the existing experimental and other theoretical values. Using the density-functional perturbation theory (DFPT) under the quasi-harmonic approximation (QHA), the temperature and pressure dependencies of the bulk modulus, the volume expansion, the thermal expansion, as well as the heat capacity at constant pressure are systematically investigated in the ranges of 0-1200 K and 0-50 GPa.
{"title":"Pressure and temperature effects on the anisotropic and thermodynamic properties of NiAl and FeAl","authors":"Lili Liu, Y. Wen, Shanshan Liu, Jing Xiong, Q. Liao","doi":"10.32908/hthp.v51.1119","DOIUrl":"https://doi.org/10.32908/hthp.v51.1119","url":null,"abstract":"We present the elastic constants of NiAl and FeAl compounds under high pressure and high temperature by using a first-principles approach. The temperature dependent elastic constants are predicted from the combinations of static volume-dependent elastic constants derived from the first-principles total-energy method within the density-functional theory (DFT). The calculated lattice and elastic constants at ground state are in agreement with the existing experimental and other theoretical values. Using the density-functional perturbation theory (DFPT) under the quasi-harmonic approximation (QHA), the temperature and pressure dependencies of the bulk modulus, the volume expansion, the thermal expansion, as well as the heat capacity at constant pressure are systematically investigated in the ranges of 0-1200 K and 0-50 GPa.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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