The orientation switching of a single azobenzene molecule on Au(111)surface excited by tunneling electrons and/or photons has been demonstrated in recent experiments.Here we investigate the rotation behavior of this m...The orientation switching of a single azobenzene molecule on Au(111)surface excited by tunneling electrons and/or photons has been demonstrated in recent experiments.Here we investigate the rotation behavior of this molecular rotor by first-principles density functional theory(DFT)calculation.The anchor phenyl ring prefers adsorption on top of the fcc hollow site,simulated by a benzene molecule on close packed atomic surface.The adsorption energy for an azobenzene molecule on Au(111)surface is calculated to be about 1.76 eV.The rotational energy profile has been mapped with one of the phenyl rings pivots around the fcc hollow site,illustrating a potential barrier about 50 meV.The results are consistent with experimental observations and valuable for exploring a broad spectrum of molecules on this noble metal surface.展开更多
In this study,tensile behavior of Nb-containing 25Cr-20Ni austenitic stainless steels composed of coarse or fine grains has been investigated at temperatures ranging from room temperature to 900℃.Results show that th...In this study,tensile behavior of Nb-containing 25Cr-20Ni austenitic stainless steels composed of coarse or fine grains has been investigated at temperatures ranging from room temperature to 900℃.Results show that the tensile strength of fine-grained specimens decreases faster than that of coarse-grained specimens,as the test temperature increases from 600℃ to 800℃.The rapidly decreasing tensile strength is attributed to the enhanced dynamic recovery and recrystallization,because additional slip systems are activated,and cross-slipping is accelerated during deformation in fine-grained specimens.After tensile testing at 700-900℃,sigma phases are formed concurrently with dynamic recrystallization in fine-grained specimens.The precipitation of sigma phases is induced by simultaneous recrystallization as the diffusion of alloying elements is accelerated during the recrystallization process.Additionally,the minimum ductility is observed in coarse-grained specimens at 800℃,which is caused by the formation of M23C6 precipitates at the grain boundaries.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21961142021,11774395,91753136,and 11727902)the Beijing Natural Science Foundation,China(Grant No.4181003)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant Nos.XDB30201000 and XDB28000000).
文摘The orientation switching of a single azobenzene molecule on Au(111)surface excited by tunneling electrons and/or photons has been demonstrated in recent experiments.Here we investigate the rotation behavior of this molecular rotor by first-principles density functional theory(DFT)calculation.The anchor phenyl ring prefers adsorption on top of the fcc hollow site,simulated by a benzene molecule on close packed atomic surface.The adsorption energy for an azobenzene molecule on Au(111)surface is calculated to be about 1.76 eV.The rotational energy profile has been mapped with one of the phenyl rings pivots around the fcc hollow site,illustrating a potential barrier about 50 meV.The results are consistent with experimental observations and valuable for exploring a broad spectrum of molecules on this noble metal surface.
基金financially supported by the Youth Innovation Promotion Association,Chinese Academy of Sciences(No.2013126)the Liao Ning Revitalization Talents Program under(No.XLYC1807022)+1 种基金the Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06G025)the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110886)。
文摘In this study,tensile behavior of Nb-containing 25Cr-20Ni austenitic stainless steels composed of coarse or fine grains has been investigated at temperatures ranging from room temperature to 900℃.Results show that the tensile strength of fine-grained specimens decreases faster than that of coarse-grained specimens,as the test temperature increases from 600℃ to 800℃.The rapidly decreasing tensile strength is attributed to the enhanced dynamic recovery and recrystallization,because additional slip systems are activated,and cross-slipping is accelerated during deformation in fine-grained specimens.After tensile testing at 700-900℃,sigma phases are formed concurrently with dynamic recrystallization in fine-grained specimens.The precipitation of sigma phases is induced by simultaneous recrystallization as the diffusion of alloying elements is accelerated during the recrystallization process.Additionally,the minimum ductility is observed in coarse-grained specimens at 800℃,which is caused by the formation of M23C6 precipitates at the grain boundaries.
