To investigate the enthalpy relaxation behavior of maltitol glass system,differential scanning calorimetry（DSC） was used to obtain the specific heat capacity[C p（T）] near the glass transition temperature（T g） at...To investigate the enthalpy relaxation behavior of maltitol glass system,differential scanning calorimetry（DSC） was used to obtain the specific heat capacity[C p（T）] near the glass transition temperature（T g） at different cooling rates ranged between 1 and 20 K/min.Three phenomenological models of enthalpy relaxation,ToolNarayanaswamy-Moynihan（TNM） model,Adam-Gibbs-Vogel（AGV） model and Gómez Ribelles（GR） model,were used to simulate the experimental data.The models＇ parameters were obtained via a curve-fitting method.The results indicate that TNM and AGV models gave the almost identical prediction powers and can reproduce the curves of experimental C p（T） very well.However,the prediction power of GR model evolved from configurational entropy approach is not so good as those of TNM and AGV models.In particular,the metastable limit state parameter（δ） introduced by Gómez Ribelles has insignificant effect on the enthalpy relaxation of the small molecular hydrogen-bonding glass system.展开更多
Dynamic mechanical performances of 30CrMnSiNi2A alloy steel under high pressure of 1-15 GPa are studied with a one stage light gas gun. With the particle velocity ranging from 150 m/s to 300 m/s, the Hugoniot curve ...Dynamic mechanical performances of 30CrMnSiNi2A alloy steel under high pressure of 1-15 GPa are studied with a one stage light gas gun. With the particle velocity ranging from 150 m/s to 300 m/s, the Hugoniot curve of 30CrMnSiNi2A alloy steel is analyzed and obtained based on the experimental data and the parameters of equation of state are obtained by calculating. The Grüneisen equation of state can be determined through these parameters.展开更多
The dispersive property of the mode Grüneisen parameter in solids is found theoretically.Such a property should appear in a reciprocal relationship to the mode frequency.This phenomenon is also confirmed experime...The dispersive property of the mode Grüneisen parameter in solids is found theoretically.Such a property should appear in a reciprocal relationship to the mode frequency.This phenomenon is also confirmed experimentally in the cases of corundum andα-quartz.展开更多
The first justified theory of solid state was proposed by Grüneisen in the year 1912 and was based on the virial theorem. The forces of interaction between two atoms were assumed as changing with distance between...The first justified theory of solid state was proposed by Grüneisen in the year 1912 and was based on the virial theorem. The forces of interaction between two atoms were assumed as changing with distance between them according to inverse power laws. But only virial theorem is insufficient to deduce the equation of state, so this author has introduced some relations, which are correct, when the forces linearly depend on displacement of atoms. But with such law of interaction the phase transitions cannot take place. Debye received Grüneisen equation in another way. He deduced the expression for thermocapacity, using Plank formula for energy of harmonic vibrator. Taking into account the dependence of atomic vibration frequency from distance between atoms, when the forces of interaction are anharmonic, he received the equation of state, which in classical limit turns to Grüneisen equation. The question, formulated by Debye is—How can we come to phase transitions, when Plank formula for harmonic vibrator was used? Debye solved this question not perfectly, because he was born to small anharmonicity. In the presented work a chain of atoms is considered, and their movement is analysed by means of relations, equivalent to virial theorem and theorem of Lucas (disappearing of mean force). Both are the results of variation principle of Hamilton. The Grüneisen equation for low temperature (not very low, where quantum expression for energy is essential) was obtained, and a family of isotherms and isobars are drown, which show the existence of spinodals, where phase transitions occur. So, Grüneisen equation is an equation of state for low temperatures.展开更多
Open framework structures(e.g.,ScF_(3),Sc_(2)W_(3O)_(12),etc.)exhibit significant potential for thermal expansion tailoring owing to their high atomic vibrational degrees of freedom and diverse connectivity between po...Open framework structures(e.g.,ScF_(3),Sc_(2)W_(3O)_(12),etc.)exhibit significant potential for thermal expansion tailoring owing to their high atomic vibrational degrees of freedom and diverse connectivity between polyhedral units,displaying positive/negative thermal expansion(PTE/NTE)coefficients at a certain temperature.Despite the proposal of several physical mechanisms to explain the origin of NTE,an accurate mapping relationship between the structural–compositional properties and thermal expansion behavior is still lacking.This deficiency impedes the rapid evaluation of thermal expansion properties and hinders the design and development of such materials.We developed an algorithm for identifying and characterizing the connection patterns of structural units in open-framework structures and constructed a descriptor set for the thermal expansion properties of this system,which is composed of connectivity and elemental information.Our developed descriptor,aided by machine learning(ML)algorithms,can effectively learn the thermal expansion behavior in small sample datasets collected from literature-reported experimental data(246 samples).The trained model can accurately distinguish the thermal expansion behavior(PTE/NTE),achieving an accuracy of 92%.Additionally,our model predicted six new thermodynamically stable NTE materials,which were validated through first-principles calculations.Our results demonstrate that developing effective descriptors closely related to thermal expansion properties enables ML models to make accurate predictions even on small sample datasets,providing a new perspective for understanding the relationship between connectivity and thermal expansion properties in the open framework structure.The datasets that were used to support these results are available on Science Data Bank,accessible via the link https://doi.org/10.57760/sciencedb.j00113.00100.展开更多
为了研究钕铁硼铁磁性材料在冲击波作用下的力学与磁学性质,利用一级轻气炮驱动飞片的方法对钕铁硼进行冲击加载实验,采用锰铜压阻传感器测量了钕铁硼内部不同位置的压力变化历程。给出了3~7 GPa压力范围内,钕铁硼的Hugoniot关系以及冲...为了研究钕铁硼铁磁性材料在冲击波作用下的力学与磁学性质,利用一级轻气炮驱动飞片的方法对钕铁硼进行冲击加载实验,采用锰铜压阻传感器测量了钕铁硼内部不同位置的压力变化历程。给出了3~7 GPa压力范围内,钕铁硼的Hugoniot关系以及冲击波阵面上压力与温度的关系;计算了钕铁硼的Grüneisen状态方程参数;建立了飞片碰撞加载钕铁硼的计算模型,对钕铁硼的冲击响应进行了数值模拟计算,计算得到的压力峰值与实验测得的压力峰值基本相符。对冲击后的磁体进行了微观结构观测,分析了钕铁硼退磁机制。结果发现:冲击后磁体发生沿晶断裂,磁体晶界相的微观结构没有发生变化,沿晶断裂弱化了晶界相隔断主相之间交换耦合的作用。经冲击的磁体的矫顽力损失很大,从21.4 k Oe降至3.2 k Oe,在难磁化方向矫顽力只有1.2 k Oe,但难易磁化方向并未发生改变。展开更多
基金Supported by the National Natural Science Foundation of China(No.20803016)the Natural Science Foundation of Anhui Province,China(No.070414163)
文摘To investigate the enthalpy relaxation behavior of maltitol glass system,differential scanning calorimetry（DSC） was used to obtain the specific heat capacity[C p（T）] near the glass transition temperature（T g） at different cooling rates ranged between 1 and 20 K/min.Three phenomenological models of enthalpy relaxation,ToolNarayanaswamy-Moynihan（TNM） model,Adam-Gibbs-Vogel（AGV） model and Gómez Ribelles（GR） model,were used to simulate the experimental data.The models＇ parameters were obtained via a curve-fitting method.The results indicate that TNM and AGV models gave the almost identical prediction powers and can reproduce the curves of experimental C p（T） very well.However,the prediction power of GR model evolved from configurational entropy approach is not so good as those of TNM and AGV models.In particular,the metastable limit state parameter（δ） introduced by Gómez Ribelles has insignificant effect on the enthalpy relaxation of the small molecular hydrogen-bonding glass system.
文摘Dynamic mechanical performances of 30CrMnSiNi2A alloy steel under high pressure of 1-15 GPa are studied with a one stage light gas gun. With the particle velocity ranging from 150 m/s to 300 m/s, the Hugoniot curve of 30CrMnSiNi2A alloy steel is analyzed and obtained based on the experimental data and the parameters of equation of state are obtained by calculating. The Grüneisen equation of state can be determined through these parameters.
文摘The dispersive property of the mode Grüneisen parameter in solids is found theoretically.Such a property should appear in a reciprocal relationship to the mode frequency.This phenomenon is also confirmed experimentally in the cases of corundum andα-quartz.
文摘The first justified theory of solid state was proposed by Grüneisen in the year 1912 and was based on the virial theorem. The forces of interaction between two atoms were assumed as changing with distance between them according to inverse power laws. But only virial theorem is insufficient to deduce the equation of state, so this author has introduced some relations, which are correct, when the forces linearly depend on displacement of atoms. But with such law of interaction the phase transitions cannot take place. Debye received Grüneisen equation in another way. He deduced the expression for thermocapacity, using Plank formula for energy of harmonic vibrator. Taking into account the dependence of atomic vibration frequency from distance between atoms, when the forces of interaction are anharmonic, he received the equation of state, which in classical limit turns to Grüneisen equation. The question, formulated by Debye is—How can we come to phase transitions, when Plank formula for harmonic vibrator was used? Debye solved this question not perfectly, because he was born to small anharmonicity. In the presented work a chain of atoms is considered, and their movement is analysed by means of relations, equivalent to virial theorem and theorem of Lucas (disappearing of mean force). Both are the results of variation principle of Hamilton. The Grüneisen equation for low temperature (not very low, where quantum expression for energy is essential) was obtained, and a family of isotherms and isobars are drown, which show the existence of spinodals, where phase transitions occur. So, Grüneisen equation is an equation of state for low temperatures.
基金the National Natural Science Foundation of China(Grant Nos.12004131,22090044,62125402,and 92061113)。
文摘Open framework structures(e.g.,ScF_(3),Sc_(2)W_(3O)_(12),etc.)exhibit significant potential for thermal expansion tailoring owing to their high atomic vibrational degrees of freedom and diverse connectivity between polyhedral units,displaying positive/negative thermal expansion(PTE/NTE)coefficients at a certain temperature.Despite the proposal of several physical mechanisms to explain the origin of NTE,an accurate mapping relationship between the structural–compositional properties and thermal expansion behavior is still lacking.This deficiency impedes the rapid evaluation of thermal expansion properties and hinders the design and development of such materials.We developed an algorithm for identifying and characterizing the connection patterns of structural units in open-framework structures and constructed a descriptor set for the thermal expansion properties of this system,which is composed of connectivity and elemental information.Our developed descriptor,aided by machine learning(ML)algorithms,can effectively learn the thermal expansion behavior in small sample datasets collected from literature-reported experimental data(246 samples).The trained model can accurately distinguish the thermal expansion behavior(PTE/NTE),achieving an accuracy of 92%.Additionally,our model predicted six new thermodynamically stable NTE materials,which were validated through first-principles calculations.Our results demonstrate that developing effective descriptors closely related to thermal expansion properties enables ML models to make accurate predictions even on small sample datasets,providing a new perspective for understanding the relationship between connectivity and thermal expansion properties in the open framework structure.The datasets that were used to support these results are available on Science Data Bank,accessible via the link https://doi.org/10.57760/sciencedb.j00113.00100.
文摘为了研究钕铁硼铁磁性材料在冲击波作用下的力学与磁学性质,利用一级轻气炮驱动飞片的方法对钕铁硼进行冲击加载实验,采用锰铜压阻传感器测量了钕铁硼内部不同位置的压力变化历程。给出了3~7 GPa压力范围内,钕铁硼的Hugoniot关系以及冲击波阵面上压力与温度的关系;计算了钕铁硼的Grüneisen状态方程参数;建立了飞片碰撞加载钕铁硼的计算模型,对钕铁硼的冲击响应进行了数值模拟计算,计算得到的压力峰值与实验测得的压力峰值基本相符。对冲击后的磁体进行了微观结构观测,分析了钕铁硼退磁机制。结果发现:冲击后磁体发生沿晶断裂,磁体晶界相的微观结构没有发生变化,沿晶断裂弱化了晶界相隔断主相之间交换耦合的作用。经冲击的磁体的矫顽力损失很大,从21.4 k Oe降至3.2 k Oe,在难磁化方向矫顽力只有1.2 k Oe,但难易磁化方向并未发生改变。
