First-principles calculations based on the density-functional theory were employed to study the crystal structure of vanadium phosphide compounds,such as V3P,V2P,VP,VP2 and VP4. Cohesive energy of five types of vanadi...First-principles calculations based on the density-functional theory were employed to study the crystal structure of vanadium phosphide compounds,such as V3P,V2P,VP,VP2 and VP4. Cohesive energy of five types of vanadium phosphide compounds was calculated to assess their structural stability. The charge density distribution and densities of states of vanadium phosphides were discussed to study further their electronic structures. The results show that the structure of metal-rich compounds is considerably more stable than the phosphorus-rich compositions,and covalent bond exists between the V and P atoms of V3P,V2P,VP,VP2 and VP4.展开更多
The preparation of large crystals is highly important for the characterization and application of a newly found structure but remains a challenge for one-dimensional(1D)C_(60) polymers.In this work,we successfully fab...The preparation of large crystals is highly important for the characterization and application of a newly found structure but remains a challenge for one-dimensional(1D)C_(60) polymers.In this work,we successfully fabricated a 1D C_(60) polymer crystal via on-site annealing of a millimeter-sized C_(60) molecular crystal withα-Li_(3)N at 500°C and ambient pres�sure.Characterizations show that the C_(60) cages in the crystal have been efficiently connected,forming 1D chains along the<110>direction in an orthorhombic 3D structure.At the same time,the crystal maintains a morphology similar to that of the pristine C_(60)crystal,providing opportunities for characterization of all the facets of the crystal via Raman spectroscopy and thus suggesting the formation mechanism of such crystals.展开更多
基金Project(20871101)supported by the National Natural Science Foundation of ChinaProject(09C945)supported by the Scientific Research Fund of Hunan Provincial Education Department,China
文摘First-principles calculations based on the density-functional theory were employed to study the crystal structure of vanadium phosphide compounds,such as V3P,V2P,VP,VP2 and VP4. Cohesive energy of five types of vanadium phosphide compounds was calculated to assess their structural stability. The charge density distribution and densities of states of vanadium phosphides were discussed to study further their electronic structures. The results show that the structure of metal-rich compounds is considerably more stable than the phosphorus-rich compositions,and covalent bond exists between the V and P atoms of V3P,V2P,VP,VP2 and VP4.
基金supported by the National Key R&D Program of China(2020YFA0711502)the National Natural Science Foundation of China(52325202,52202052,52373310)。
文摘The preparation of large crystals is highly important for the characterization and application of a newly found structure but remains a challenge for one-dimensional(1D)C_(60) polymers.In this work,we successfully fabricated a 1D C_(60) polymer crystal via on-site annealing of a millimeter-sized C_(60) molecular crystal withα-Li_(3)N at 500°C and ambient pres�sure.Characterizations show that the C_(60) cages in the crystal have been efficiently connected,forming 1D chains along the<110>direction in an orthorhombic 3D structure.At the same time,the crystal maintains a morphology similar to that of the pristine C_(60)crystal,providing opportunities for characterization of all the facets of the crystal via Raman spectroscopy and thus suggesting the formation mechanism of such crystals.
