In order to compare the influence of two commonly used molecular potentials: L-J (Lennard-Jones) 6-12 potential and EXP-6 (exponential-6) potential on the accuracy of calculating pressure-volume-temperature (PVT) relations of high temperature and high pressure gas by high order virial equation of state (EOS). In this paper, using the Kihara’s calculation method, the third order dimensionless virial coefficients of EXP- 6 potential (α=12) and EXP-6 potential (α=13) in dimensionless temperature T* =1- 500 are calculated. Using the orthogonal integration method proposed by Barker, the fourth and fifth order dimensionless virial coefficients of L-J 6-12 potential, EXP-6 potential (α=12) and EXP-6 potential (α=13) in T* =1-500 are calculated. By fitting these theoretical values, the corresponding high order virial EOS: VLJ, VEXP612 and VEXP613, are established. Using VLJ, VEXP612 and VEXP613 EOS to calculate the PVT relations of methane, oxygen, carbon dioxide and carbon monoxide under high temperature and high pressure, the accuracy and applicability of the two molecular potentials in the description of PVT relations of high temperature and high pressure gases are analyzed and evaluated by comparison. On this basis, the characteristics of intermolecular interaction in high temperature and high pressure gas are further analyzed.
{"title":"Influence of molecular potential type on the accuracy of virial equation of state in describing PVT relations of high temperature and high pressure gas","authors":"Yue Peng","doi":"10.32908/hthp.v52.1327","DOIUrl":"https://doi.org/10.32908/hthp.v52.1327","url":null,"abstract":"In order to compare the influence of two commonly used molecular potentials: L-J (Lennard-Jones) 6-12 potential and EXP-6 (exponential-6) potential on the accuracy of calculating pressure-volume-temperature (PVT) relations of high temperature and high pressure gas by high order virial equation of state (EOS). In this paper, using the Kihara’s calculation method, the third order dimensionless virial coefficients of EXP- 6 potential (α=12) and EXP-6 potential (α=13) in dimensionless temperature T* =1- 500 are calculated. Using the orthogonal integration method proposed by Barker, the fourth and fifth order dimensionless virial coefficients of L-J 6-12 potential, EXP-6 potential (α=12) and EXP-6 potential (α=13) in T* =1-500 are calculated. By fitting these theoretical values, the corresponding high order virial EOS: VLJ, VEXP612 and VEXP613, are established. Using VLJ, VEXP612 and VEXP613 EOS to calculate the PVT relations of methane, oxygen, carbon dioxide and carbon monoxide under high temperature and high pressure, the accuracy and applicability of the two molecular potentials in the description of PVT relations of high temperature and high pressure gases are analyzed and evaluated by comparison. On this basis, the characteristics of intermolecular interaction in high temperature and high pressure gas are further analyzed.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69443328","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 strain and magnetic field effect on thermodynamic properties of a two dimensional GaAs quantum dot (QD) is investigated within the effective mass approximation. To this end, first we have obtained the wave functions and energy levels of the system in the presence of Bychkov-Rashba and Dressalhaus terms. Then using the obtained energy levels, we have computed the partition function by the Poisson summation formalism. Afterward, we have deduced some thermodynamic properties such as mean energy, entropy, specific heat and free energy using the canonical ensemble approach. Finally, the thermodynamic properties for a two dimensional GaAs QD have been discussed in detail.
{"title":"Strain and magnetic field effect on thermodynamic properties of a two dimensional GaAs quantum dot","authors":"Ahmad Ghanbari","doi":"10.32908/hthp.v52.1391","DOIUrl":"https://doi.org/10.32908/hthp.v52.1391","url":null,"abstract":"The strain and magnetic field effect on thermodynamic properties of a two dimensional GaAs quantum dot (QD) is investigated within the effective mass approximation. To this end, first we have obtained the wave functions and energy levels of the system in the presence of Bychkov-Rashba and Dressalhaus terms. Then using the obtained energy levels, we have computed the partition function by the Poisson summation formalism. Afterward, we have deduced some thermodynamic properties such as mean energy, entropy, specific heat and free energy using the canonical ensemble approach. Finally, the thermodynamic properties for a two dimensional GaAs QD have been discussed in detail.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135712618","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}
S. Sukenaga, R. Ikoma, M. Tashiro, Y. Chiba, S. Kawanishi, H. Shibata
The effect of alumina addition on the viscosity of silicate melts is strongly related to the type of non-framework cations; however, the origin of these interactions is not well understood. In this study, we measured the viscosity change in selected alkali disilicate (R2O·2SiO2, R: Na or Li) melts by varying the AlO1.5/SiO2 molar ratio (AlO1.5 = 0–16.8 mol%) within the 1373–1823 K temperature range. We observed that as the molar ratio increased, sodium silicate viscosity increased, whereas lithium silicate viscosity was not affected. Aluminum-27 nuclear magnetic resonance spectra of the quenched glasses indicated that the aluminum cations in both types of alkali silicate melts were mostly present as AlO4 tetrahedra. In contrast to sodium-containing systems, the shear strain on the AlO4 tetrahedron was greater for lithium aluminosilicate glass. Our findings indicated that the degree of shear strain on AlO4 plays an essential role in controlling the viscosity of aluminosilicate systems.
{"title":"AlO1.5/SiO2 substitution effect on the viscosity of alkali silicate melts","authors":"S. Sukenaga, R. Ikoma, M. Tashiro, Y. Chiba, S. Kawanishi, H. Shibata","doi":"10.32908/hthp.v52.1437","DOIUrl":"https://doi.org/10.32908/hthp.v52.1437","url":null,"abstract":"The effect of alumina addition on the viscosity of silicate melts is strongly related to the type of non-framework cations; however, the origin of these interactions is not well understood. In this study, we measured the viscosity change in selected alkali disilicate (R2O·2SiO2, R: Na or Li) melts by varying the AlO1.5/SiO2 molar ratio (AlO1.5 = 0–16.8 mol%) within the 1373–1823 K temperature range. We observed that as the molar ratio increased, sodium silicate viscosity increased, whereas lithium silicate viscosity was not affected. Aluminum-27 nuclear magnetic resonance spectra of the quenched glasses indicated that the aluminum cations in both types of alkali silicate melts were mostly present as AlO4 tetrahedra. In contrast to sodium-containing systems, the shear strain on the AlO4 tetrahedron was greater for lithium aluminosilicate glass. Our findings indicated that the degree of shear strain on AlO4 plays an essential role in controlling the viscosity of aluminosilicate systems.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69443744","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}
Nenad Milošević, Ivana Nikolić, Marc Grelard, Bruno Hay
This paper presents experimental results on five thermophysical properties of the TZM alloy over a wide temperature range. Specific heat and specific electrical resistivity were measured from room temperature to 2200 °C and 2450 °C, respectively, normal spectral emissivity at 900 nm from 1150 °C to 2300 °C, hemispherical total emissivity from 1100 °C to 2450 °C and the coefficient of the linear thermal expansion from room temperature to 2000 °C. The specific heat, specific electrical resistivity and both emissivities were obtained by the direct pulse heating technique or pulse calorimetry, while the thermal expansion coefficient by the pushrod dilatometry. The specimens in the form of a thin rod were used, 200 mm in length and 3 mm in diameter in the first, while 25 mm in length and 6 mm in diameter in the second technique. The results are presented and compared with available literature data.
{"title":"Thermophysical properties of the molybdenum alloy TZM (Mo-0.5Ti-0.08Zr-0.02C) over a wide temperature range","authors":"Nenad Milošević, Ivana Nikolić, Marc Grelard, Bruno Hay","doi":"10.32908/hthp.v52.1425","DOIUrl":"https://doi.org/10.32908/hthp.v52.1425","url":null,"abstract":"This paper presents experimental results on five thermophysical properties of the TZM alloy over a wide temperature range. Specific heat and specific electrical resistivity were measured from room temperature to 2200 °C and 2450 °C, respectively, normal spectral emissivity at 900 nm from 1150 °C to 2300 °C, hemispherical total emissivity from 1100 °C to 2450 °C and the coefficient of the linear thermal expansion from room temperature to 2000 °C. The specific heat, specific electrical resistivity and both emissivities were obtained by the direct pulse heating technique or pulse calorimetry, while the thermal expansion coefficient by the pushrod dilatometry. The specimens in the form of a thin rod were used, 200 mm in length and 3 mm in diameter in the first, while 25 mm in length and 6 mm in diameter in the second technique. The results are presented and compared with available literature data.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135712603","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}
H. Oda, Rina Shimonishi, Chihiro Koyama, Tsuyoshi Ito, T. Ishikawa
This work employed the electrostatic levitation furnace (ELF) apparatus installed in the KIBO Japanese Experiment Module on the International Space Station. The ELF is able to levitate high-melting-point materials such as ceramics without containers. The heating and melting of refractory oxides in this apparatus allows the analysis of various thermophysical properties, including density, surface tension and viscosity, that are otherwise very difficult to measure in terrestrial laboratories. In the present study, the density of molten Y2O3 was determined over a wide temperature range using the ELF. A density of 4700 kg/m3 was obtained at 2712 K, in good agreement with the value previously obtained using an aero-acoustic levitator. The relationship between the ionic radius and the molar volume of liquid Y2O3 was ascertained and found to be similar to those for other non-glass-forming sesquioxides.
{"title":"Determining the density of molten Y2O3 using an electrostatic levitation furnace in the International Space Station","authors":"H. Oda, Rina Shimonishi, Chihiro Koyama, Tsuyoshi Ito, T. Ishikawa","doi":"10.32908/hthp.v52.1375","DOIUrl":"https://doi.org/10.32908/hthp.v52.1375","url":null,"abstract":"This work employed the electrostatic levitation furnace (ELF) apparatus installed in the KIBO Japanese Experiment Module on the International Space Station. The ELF is able to levitate high-melting-point materials such as ceramics without containers. The heating and melting of refractory oxides in this apparatus allows the analysis of various thermophysical properties, including density, surface tension and viscosity, that are otherwise very difficult to measure in terrestrial laboratories. In the present study, the density of molten Y2O3 was determined over a wide temperature range using the ELF. A density of 4700 kg/m3 was obtained at 2712 K, in good agreement with the value previously obtained using an aero-acoustic levitator. The relationship between the ionic radius and the molar volume of liquid Y2O3 was ascertained and found to be similar to those for other non-glass-forming sesquioxides.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69443195","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}
Prediction of critical point is of great interest for CO2-based binary mixture being the working fluid of power cycle. Compared with empirical correlation, the critical point of mixture can be calculated based on its rigorous thermodynamic criteria, with limited binary interaction parameters and consistency on vapor-liquid equilibrium and other thermodynamic properties. In this study, the critical points of CO2-based binary mixture, applicable for being working fluid of power cycle, including hydrocarbons, fluorocarbons, dimethyl ether, methanol, water and xenon, were studied based on the Peng-Robinson equation of state (PR EOS) with van der Waals (vdW) mixing rule, according to the Heidemann-Khalil approach. By comparing the predicted results with the experimental data in the literature, the applicability of this method to various mixtures is discussed. The characteristics of critical lines, type of phase diagram, and binary interaction parameters of each mixture were analyzed and discussed, and the results show that the Heidemann-Khalil approach is efficient for critical point calculation and prediction of CO2-based binary mixture.
对于作为动力循环工质的二氧化碳基二元混合物，临界点的预测具有重要意义。与经验关联相比，混合物的临界点可以根据其严格的热力学准则计算，二元相互作用参数有限，汽液平衡和其他热力学性质一致。本研究根据Heidemann-Khalil方法，基于van der Waals (vdW)混合规则的Peng-Robinson状态方程(PR EOS)，研究了适用于动力循环工质的co2基二元混合物的临界点，包括碳氢化合物、氟碳化合物、二甲醚、甲醇、水和氙。通过将预测结果与文献中的实验数据进行比较，讨论了该方法对各种混合物的适用性。分析和讨论了每种混合物的临界线特征、相图类型和二元相互作用参数，结果表明Heidemann-Khalil方法对于co2基二元混合物的临界点计算和预测是有效的。
{"title":"Prediction of critical points for carbon dioxide-based binary mixtures by the Heidemann-Khalil approach","authors":"Rui Sun, Hua Tian, Gequn Shu","doi":"10.32908/hthp.v52.1441","DOIUrl":"https://doi.org/10.32908/hthp.v52.1441","url":null,"abstract":"Prediction of critical point is of great interest for CO2-based binary mixture being the working fluid of power cycle. Compared with empirical correlation, the critical point of mixture can be calculated based on its rigorous thermodynamic criteria, with limited binary interaction parameters and consistency on vapor-liquid equilibrium and other thermodynamic properties. In this study, the critical points of CO2-based binary mixture, applicable for being working fluid of power cycle, including hydrocarbons, fluorocarbons, dimethyl ether, methanol, water and xenon, were studied based on the Peng-Robinson equation of state (PR EOS) with van der Waals (vdW) mixing rule, according to the Heidemann-Khalil approach. By comparing the predicted results with the experimental data in the literature, the applicability of this method to various mixtures is discussed. The characteristics of critical lines, type of phase diagram, and binary interaction parameters of each mixture were analyzed and discussed, and the results show that the Heidemann-Khalil approach is efficient for critical point calculation and prediction of CO2-based binary mixture.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135712282","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}
Milena Milich, Kathleen F. Quiambao-Tomko, J. Tomko, J. Maria, P. Hopkins
High entropy carbides (HECs) are a promising new class of ultra-high temperature ceramics that could provide novel material solutions for leading edges of hypersonic vehicles, which can reach temperatures > 3,500 �C and experience extreme thermal gradients. Although the mechanical and thermal properties of HECs have been studied extensively at room temperature, few works have examined HEC properties at high temperatures or considered these materials� responses to thermal shock. In this work, we measure the thermal conductivity of a five-cation HEC up to 1200 �C. We find that thermal conductivity increases with temperature, consistent with trends demonstrated in single-metal carbides. We also measure thermal conductivity of an HEC deposited with varying CH4 flow rate, and find that although thermal conductivity is reduced when carbon content surpasses stoichiometric concentrations, the films all exhibited the same temperature dependent trends regardless of carbon content. To compare the thermal shock resistance of HECs with a refractory carbide, we conduct pulsed laser ablation measurements to determine the fluence threshold the HECs can withstand before damaging. We find that this metric for the average bond strength trends with the theoretical hardness of the HECs as expected.
{"title":"Ablation threshold and temperature dependent thermal conductivity of high entropy carbide thin films","authors":"Milena Milich, Kathleen F. Quiambao-Tomko, J. Tomko, J. Maria, P. Hopkins","doi":"10.32908/hthp.v52.1343","DOIUrl":"https://doi.org/10.32908/hthp.v52.1343","url":null,"abstract":"High entropy carbides (HECs) are a promising new class of ultra-high temperature ceramics that could provide novel material solutions for leading edges of hypersonic vehicles, which can reach temperatures > 3,500 �C and experience extreme thermal gradients. Although the mechanical and thermal properties of HECs have been studied extensively at room temperature, few works have examined HEC properties at high temperatures or considered these materials� responses to thermal shock. In this work, we measure the thermal conductivity of a five-cation HEC up to 1200 �C. We find that thermal conductivity increases with temperature, consistent with trends demonstrated in single-metal carbides. We also measure thermal conductivity of an HEC deposited with varying CH4 flow rate, and find that although thermal conductivity is reduced when carbon content surpasses stoichiometric concentrations, the films all exhibited the same temperature dependent trends regardless of carbon content. To compare the thermal shock resistance of HECs with a refractory carbide, we conduct pulsed laser ablation measurements to determine the fluence threshold the HECs can withstand before damaging. We find that this metric for the average bond strength trends with the theoretical hardness of the HECs as expected.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46675595","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}
Lithium-ion batteries are increasingly used in the field of new energy vehicles. Thermal runaway is the biggest potential safety hazard. In order to achieve safer battery design, it is necessary to fully understand thermal runaway. In this research, the thermal abuse model of lithium-ion battery module is established. Temperature propagation characteristics of lithiumion battery pack under high temperature heat source is discussed and analyzed. The results show that there is consistency in the thermal runaway of lithium-ion battery at different surface heat source temperatures, and the thermal runaway of lithium-ion battery packs occurs at 453 K. The location of surface heat source only affects the distribution of temperature when thermal runaway occurs. The smaller the thermal conductivity of the battery spacer layer, the slower the temperature propagation when the battery is out of control.
{"title":"Analysis of thermal runaway propagation characteristics of lithium-ion battery module under local high temperature","authors":"Tong Hu, Fei Ma, Xiaoming Xu","doi":"10.32908/hthp.v51.1165","DOIUrl":"https://doi.org/10.32908/hthp.v51.1165","url":null,"abstract":"Lithium-ion batteries are increasingly used in the field of new energy vehicles. Thermal runaway is the biggest potential safety hazard. In order to achieve safer battery design, it is necessary to fully understand thermal runaway. In this research, the thermal abuse model of lithium-ion battery module is established. Temperature propagation characteristics of lithiumion battery pack under high temperature heat source is discussed and analyzed. The results show that there is consistency in the thermal runaway of lithium-ion battery at different surface heat source temperatures, and the thermal runaway of lithium-ion battery packs occurs at 453 K. The location of surface heat source only affects the distribution of temperature when thermal runaway occurs. The smaller the thermal conductivity of the battery spacer layer, the slower the temperature propagation when the battery is out of control.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442567","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}
Souad Messai, L. Chrusciel, O. Al-Hagan, Mona Almuadi, J. Sghaier
This work presents a comparative study of four drying processes of a porous media: superheated steam drying at atmospheric pressure (APSSD), humid air (HA), low pressure superheated steam drying (LPSSD) and vacuum drying (VD). A single porous particle model has been developed to simulate the four drying processes. The model is based on the method of averaging volume. Spherical porous particles of coal are used as the model material in this paper. The evaporation rates are equal for these processes in point called the inversion temperature. This temperature was calculated during the constant rate period (CRP) and the falling rate period (FRP). A variation in the values of inversion temperature was observed (363-503 K). The effect of drying parameters such as: particle radius, gas mass flux, permeability, porosity and operating pressure were investigated. Several researchers have reported the noticeable variation of the inversion temperature values according to the drying period used to calculate this key parameter. Our results are compared with those obtained from a front model reported in the literature. A good agreement is found.
{"title":"Study and comparison of different drying processes of porous particle at high temperature","authors":"Souad Messai, L. Chrusciel, O. Al-Hagan, Mona Almuadi, J. Sghaier","doi":"10.32908/hthp.v51.1103","DOIUrl":"https://doi.org/10.32908/hthp.v51.1103","url":null,"abstract":"This work presents a comparative study of four drying processes of a porous media: superheated steam drying at atmospheric pressure (APSSD), humid air (HA), low pressure superheated steam drying (LPSSD) and vacuum drying (VD). A single porous particle model has been developed to simulate the four drying processes. The model is based on the method of averaging volume. Spherical porous particles of coal are used as the model material in this paper. The evaporation rates are equal for these processes in point called the inversion temperature. This temperature was calculated during the constant rate period (CRP) and the falling rate period (FRP). A variation in the values of inversion temperature was observed (363-503 K). The effect of drying parameters such as: particle radius, gas mass flux, permeability, porosity and operating pressure were investigated. Several researchers have reported the noticeable variation of the inversion temperature values according to the drying period used to calculate this key parameter. Our results are compared with those obtained from a front model reported in the literature. A good agreement is found.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442874","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}
Based on density functional theory and Debye quasi-harmonic approximation, the effects of high pressure on the phonon, electronic, elastic, and thermodynamic properties of the orthogonal phase HfSi2 have been calculated. The calculated results show that when the pressure is within the pressure range of 0 GPa to 50 GPa, HfSi2 is dynamically stable, and there is no virtual frequency on the phonon spectrum, but when the pressure is greater than 70 GPa, virtual frequencies appear near the phonon spectrum X, A structural phase change occurred. We predict that the band structure of HfSi2 is metallic. As the pressure increases, the elastic constant Cij increases and conforms to the Born criterion. It is mechanically stable in a certain pressure range. At the same time, B, E, G, and B/G all increase with the increase of pressure. This shows that changing the pressure appropriately can change the ductility and toughness of the material. The Debye temperature and sound velocity increase linearly with the increase of pressure, so the elasticity, hardness, melting point, and specific heat of the material can be improved by pressure.
{"title":"First-principle study of phonon, elastic and thermodynamic properties of HfSi2 under high pressure","authors":"Jinjuan Sun, Yu-Long Han, X. Yao","doi":"10.32908/hthp.v51.1193","DOIUrl":"https://doi.org/10.32908/hthp.v51.1193","url":null,"abstract":"Based on density functional theory and Debye quasi-harmonic approximation, the effects of high pressure on the phonon, electronic, elastic, and thermodynamic properties of the orthogonal phase HfSi2 have been calculated. The calculated results show that when the pressure is within the pressure range of 0 GPa to 50 GPa, HfSi2 is dynamically stable, and there is no virtual frequency on the phonon spectrum, but when the pressure is greater than 70 GPa, virtual frequencies appear near the phonon spectrum X, A structural phase change occurred. We predict that the band structure of HfSi2 is metallic. As the pressure increases, the elastic constant Cij increases and conforms to the Born criterion. It is mechanically stable in a certain pressure range. At the same time, B, E, G, and B/G all increase with the increase of pressure. This shows that changing the pressure appropriately can change the ductility and toughness of the material. The Debye temperature and sound velocity increase linearly with the increase of pressure, so the elasticity, hardness, melting point, and specific heat of the material can be improved by pressure.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442632","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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