Based on the electron-holding energy per unit volume,we extend the concept of hardness to atomic stiffness,ionic stiffness and bond hardness,investigating the nature of material hardness at these three levels. We find...Based on the electron-holding energy per unit volume,we extend the concept of hardness to atomic stiffness,ionic stiffness and bond hardness,investigating the nature of material hardness at these three levels. We find that the stiffness of isolated atoms or ions has no direct connection with the hardness of materials,whereas material hardness is directly related to bond hardness,which is es-sentially determined by the electron-holding energy of its constituent chemical bonds per unit volume. We establish a model for identifying the hardness of materials on the basis of bond hardness. This work offers a deeper understanding of the nature of material hardness at the atomic level,and provides a practical guide in the search for new superhard materials.展开更多
The concept of electronegativity (EN), which was proposed by Pauling in 1932, is closely related to such properties of molecules as the polarizability, hardness (softness) and charge distribution, and is an important ...The concept of electronegativity (EN), which was proposed by Pauling in 1932, is closely related to such properties of molecules as the polarizability, hardness (softness) and charge distribution, and is an important theoretical basis for judging the properties of substances. With the development of new materials and the increase of interdisciplinary cooperation, EN has been a basic atomic parameter which is widely used in the fields of chemistry, physics and materials science. The development of EN has involved three stages, atomic EN, ionic EN and bond EN. The ionic EN, which is the EN values of elements in different valence states by including the chemical environment of atoms, accurately describes various physical and chemical properties of ions and compounds. The bond EN is a bridge linking atomic EN and the properties of materials, which helps us to establish the quantitative correlation between macroscopic properties and microscopic electronic structures of materials. The concepts of ionic EN and bond EN broaden the scope of EN theory, and play important roles in the design of novel materials. This paper presents a detailed introduction of a new development of EN and its applications in materials research.展开更多
基金Supported by National Natural Science Foundation of China (Grant No.20471012)Program for New Century Excellent Talents in University (Grant No.NCET-05-0278)Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 200322)
文摘Based on the electron-holding energy per unit volume,we extend the concept of hardness to atomic stiffness,ionic stiffness and bond hardness,investigating the nature of material hardness at these three levels. We find that the stiffness of isolated atoms or ions has no direct connection with the hardness of materials,whereas material hardness is directly related to bond hardness,which is es-sentially determined by the electron-holding energy of its constituent chemical bonds per unit volume. We establish a model for identifying the hardness of materials on the basis of bond hardness. This work offers a deeper understanding of the nature of material hardness at the atomic level,and provides a practical guide in the search for new superhard materials.
基金Supported by the Program for New Century Excellent Talents in University (Grant No. NCET-05-0278)Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 200322)
文摘The concept of electronegativity (EN), which was proposed by Pauling in 1932, is closely related to such properties of molecules as the polarizability, hardness (softness) and charge distribution, and is an important theoretical basis for judging the properties of substances. With the development of new materials and the increase of interdisciplinary cooperation, EN has been a basic atomic parameter which is widely used in the fields of chemistry, physics and materials science. The development of EN has involved three stages, atomic EN, ionic EN and bond EN. The ionic EN, which is the EN values of elements in different valence states by including the chemical environment of atoms, accurately describes various physical and chemical properties of ions and compounds. The bond EN is a bridge linking atomic EN and the properties of materials, which helps us to establish the quantitative correlation between macroscopic properties and microscopic electronic structures of materials. The concepts of ionic EN and bond EN broaden the scope of EN theory, and play important roles in the design of novel materials. This paper presents a detailed introduction of a new development of EN and its applications in materials research.
