Density functional theory（DFT） calculations are performed to investigate the reactivity of Th atom toward ethane C–C bond activation.A comprehensive description of the reaction mechanisms leading to two different r...Density functional theory（DFT） calculations are performed to investigate the reactivity of Th atom toward ethane C–C bond activation.A comprehensive description of the reaction mechanisms leading to two different reaction products is presented.We report a complete exploration of the potential energy surfaces by taking into consideration different spin states.In addition,the intermediate and transition states along the reaction paths are characterized.Total,partial,and overlap population density of state diagrams and analyses are also presented.Furthermore,the natures of the chemical bonding of intermediate and transition states are studied by using topological method combined with electron localization function（ELF） and Mayer bond order.Infrared spectrum（IR） is obtained and further discussed based on the optimized geometries.展开更多
We obtained the reaction mechanism of cerium with oxygen by means of density functional theory (DFT) under the explosive or detonation situation. The energy level order of cerium was calculated and the potential energ...We obtained the reaction mechanism of cerium with oxygen by means of density functional theory (DFT) under the explosive or detonation situation. The energy level order of cerium was calculated and the potential energy profile was plotted. The properties of the bonds of all special structures in the reaction path were analyzed using the method of the electron localization function (ELF). The results indicate that the final reaction pathway can be expressed as Ce+O2→ FC→TS→IM→O-Ce-O, and the formation of Ce2O3 has not been found. In addition, the ELF diagram of the final product CeO2 shows that Ce bonds with both O atoms and the bond angles increase significantly.展开更多
Novel Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0-0.8)ceramics,designed by replacing Ce^(4+)with Yb^(3+)ions were prepared by conventional oxide reaction,and the structural stability of the cubic fluorite structure was assessed usin...Novel Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0-0.8)ceramics,designed by replacing Ce^(4+)with Yb^(3+)ions were prepared by conventional oxide reaction,and the structural stability of the cubic fluorite structure was assessed using lattice energy and ionic properties of Ce/Yb-O bonds.The oxygen vacancy caused by unequal substitution,which played a decisive role in bond ionicity and lattice energy,was analyzed experimentally by XPS and also theoretically by first principles.The Yb_(x)Ce_(1-x)O_(2-0.5x) ceramics maintain a stable cubic fluorite structure when x≤0.47,corresponding to the minimum lattice energy of 4142 kJ/mol with the lowest ionicity as ƒ_(i)=87.57%.For microwave dielectric properties,when the Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0-0.4)ceramics are pure phase,the porosity-corrected permittivity is dependent on the bond ionicity.The Q׃ values are related to the lattice energy and grain distribution.The temperature coefficient of resonance frequency has been analyzed using bond valence.When the Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0.5-0.8)ceramics are multiple phases,the microwave dielectric properties are associated with the phase composition and grain growth.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21371160,21401173,and 11364023)
文摘Density functional theory（DFT） calculations are performed to investigate the reactivity of Th atom toward ethane C–C bond activation.A comprehensive description of the reaction mechanisms leading to two different reaction products is presented.We report a complete exploration of the potential energy surfaces by taking into consideration different spin states.In addition,the intermediate and transition states along the reaction paths are characterized.Total,partial,and overlap population density of state diagrams and analyses are also presented.Furthermore,the natures of the chemical bonding of intermediate and transition states are studied by using topological method combined with electron localization function（ELF） and Mayer bond order.Infrared spectrum（IR） is obtained and further discussed based on the optimized geometries.
文摘We obtained the reaction mechanism of cerium with oxygen by means of density functional theory (DFT) under the explosive or detonation situation. The energy level order of cerium was calculated and the potential energy profile was plotted. The properties of the bonds of all special structures in the reaction path were analyzed using the method of the electron localization function (ELF). The results indicate that the final reaction pathway can be expressed as Ce+O2→ FC→TS→IM→O-Ce-O, and the formation of Ce2O3 has not been found. In addition, the ELF diagram of the final product CeO2 shows that Ce bonds with both O atoms and the bond angles increase significantly.
基金the Fundamental Research Funds for the Central Universities(Grant No.2020ZDPYMS12).
文摘Novel Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0-0.8)ceramics,designed by replacing Ce^(4+)with Yb^(3+)ions were prepared by conventional oxide reaction,and the structural stability of the cubic fluorite structure was assessed using lattice energy and ionic properties of Ce/Yb-O bonds.The oxygen vacancy caused by unequal substitution,which played a decisive role in bond ionicity and lattice energy,was analyzed experimentally by XPS and also theoretically by first principles.The Yb_(x)Ce_(1-x)O_(2-0.5x) ceramics maintain a stable cubic fluorite structure when x≤0.47,corresponding to the minimum lattice energy of 4142 kJ/mol with the lowest ionicity as ƒ_(i)=87.57%.For microwave dielectric properties,when the Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0-0.4)ceramics are pure phase,the porosity-corrected permittivity is dependent on the bond ionicity.The Q׃ values are related to the lattice energy and grain distribution.The temperature coefficient of resonance frequency has been analyzed using bond valence.When the Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0.5-0.8)ceramics are multiple phases,the microwave dielectric properties are associated with the phase composition and grain growth.
