In order to investigate the real-time cracking behavior of each component of a composite with strong interfacial bonding among lamellae, Ti-18 Nb(at.%) composite was prepared by spark plasma sintering(SPS), followed b...In order to investigate the real-time cracking behavior of each component of a composite with strong interfacial bonding among lamellae, Ti-18 Nb(at.%) composite was prepared by spark plasma sintering(SPS), followed by hot-rolling, annealing, and quenching. The microstructure and mechanical properties were characterized by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), micro-region X-ray diffractometry(MRXRD), nanoindentation, and in-situ scanning electron microscopy tensile testing. The results show that the Ti-18 Nb consists of Ti-enriched, diffusion and Nb-enriched zones, and the sharp Nb gradient across different zones leads to inhomogeneous distribution of phase and mechanical properties. A remarkable finding is that the diffusion zones not only enable the cooperative deformation between the brittle Ti-enriched zones and the ductile Nb-enriched zones but also act as the crack-arresters to prevent the local cracks in the Ti-enriched zones from further propagating across the composite.展开更多
The mechanism of contact electrification between metals was studied using the first-principles method, taking the Ag-Fe contact as an example. Charge population, charge density difference, the orbitals and densities o...The mechanism of contact electrification between metals was studied using the first-principles method, taking the Ag-Fe contact as an example. Charge population, charge density difference, the orbitals and densities of states （DOS） were calculated to study the electronic properties of the contacting interfacial atoms. Based on the calculation, the amount of contact charge was obtained. The investigation revealed that the electrons near Fermi levels with higher energies transfer between the outermost orbitals （s orbitals for Ag and d orbitals for Fe）. Meanwhile, polarized covalent bonds form between the d electrons in the deep energy states. These two effects together lead to an increase of charge magnitude at the interface. Also, the electrons responsible for electrification can be determined by their energies and orbitals.展开更多
The title complex cis-bis（tetrahydrothiophene）-bis（nitrate） platinum（H）, （tht）2Pt（NO3）2, was the reducing product from potassium hexachloroplatinate（IV） K2PtC16 where the platinum is tetra-valenced. Crysta...The title complex cis-bis（tetrahydrothiophene）-bis（nitrate） platinum（H）, （tht）2Pt（NO3）2, was the reducing product from potassium hexachloroplatinate（IV） K2PtC16 where the platinum is tetra-valenced. Crystal data for CsH16N206PtS2： monoclinic, space group P21/c, a = 9.8833（5）, b = 8.6744（4）, c = 18.6407（9）A,β = 114.401（3）°, V = 1455.35（12）A3 Z = 4, Mr = 495.44, Dc = 2.261 g/cm3, F（000） = 944,μ = 9.950 mm-1, 2（MoKa） = 0.71073 A, T= 293（2） K, 2θmax = 54.96°, GOOF = 1.033, R = 0.0350 and wR = 0.0785 for 2572 observed reflections with I 〉 2σ（I）. X-ray diffraction studies reveal that the title complex has interesting weak metal-metal interactions and two molecules linked by metal-metal interaction exist as a group. Luminescent spectrum illuminates red emission of the complex at room temperature.展开更多
Molecular structure of a naphthyridine and pyrazine amine ligand, N2,N7-di（pyrazin-2-yl）-1,8-naphthyri-dine-2,7-diamine（H2dpznda 1） was studied, and a three-dimensional supramolecular network with a double helix c...Molecular structure of a naphthyridine and pyrazine amine ligand, N2,N7-di（pyrazin-2-yl）-1,8-naphthyri-dine-2,7-diamine（H2dpznda 1） was studied, and a three-dimensional supramolecular network with a double helix chain structure through intermolecular hydrogen bonds and π-π interactions between the naphthyridine and pyrazine rings was depicted. Through ligand 1, [Co2（μ2-dpznda）2（μ2-CH3OH）2]（2） was obtained and two ligands coordinate to two Co2＋）as tetradentate bridging ligands. Single crystal and magnetism study on 2 revealed that the complex exhibited weak yet significant metal-metal interaction.展开更多
We report here the synthesis and characterization of two new members of the M2 E 12 family of endohe-dral Zintl clusters,[Fe_(2)Sn_(4)Bi_(8)]^(3-)and[Cr_(2)Sb_(12)]^(3-),both of which contain open-shell metal dimers e...We report here the synthesis and characterization of two new members of the M2 E 12 family of endohe-dral Zintl clusters,[Fe_(2)Sn_(4)Bi_(8)]^(3-)and[Cr_(2)Sb_(12)]^(3-),both of which contain open-shell metal dimers encap-sulated inside a triple-decker cluster of main-group atoms.The 75-electron[Fe_(2)Sn_(4)Bi_(8)]^(3-)cluster has a D4h-symmetric structure,while[Cr_(2)Sb_(12)]^(3-),despite having the same 75-electron count,is strongly dis-torted to a geometry that resembles a CrSb_(8)crown capped by a CrSb_(4)unit.The structural differences between the two are driven by the increasing availability of 3d electron density in the earlier transi-tion metal,which leads,ultimately,to different electronic configurations in the two clusters.The trends precisely mirror those observed in the ME_(10)and ME_(12)families containing a single transition metal ion.展开更多
Co_(2)VO_(4) with Co tetrahedrons and octahedrons of transition metal oxides has achieved progress in electrocatalysts and batteries.However,high metal-metal interactions make it challenging to maintain high reactivit...Co_(2)VO_(4) with Co tetrahedrons and octahedrons of transition metal oxides has achieved progress in electrocatalysts and batteries.However,high metal-metal interactions make it challenging to maintain high reactivity as well as increase the conductivity and stability of supercapacitors.In this work,spinel-structured CoZn_(0.5)V_(1.5)O_(4) with a high specific surface area was synthesized through an ion-exchange process from the metal-organic frameworks of zinc-cobalt.Density functional theory calculations indicate that the replacement of transition metal by Zn can decrease the interaction between the transition metals,leading to a downshift in the π^(∗)-orbitals(V-O)and half-filled a_(1g) orbitals near the Fermi level,thus increasing the conductivity and stability of CoZn_(0.5)V_(1.5)O_(4).As a supercapacitor electrode,CoZn_(0.5)V_(1.5)O_(4) exhibits high cycling durability(99.4% capacitance retention after 18,000 cycles)and specific capacitance(1100mFcm^(-2) at 1mAcm^(-2)).This work provides the possibility of designing octahedral and tetrahedral sites in transition metal oxides to improve their electrochemical performance.展开更多
Many experimental results have shown that the property of amorphous alloys has certain relation with composition, because the change in composition can result in change in structure of amorphous alloys.So in order to ...Many experimental results have shown that the property of amorphous alloys has certain relation with composition, because the change in composition can result in change in structure of amorphous alloys.So in order to understand the influence展开更多
Comprehensive Summary The experimental investigation of rare-earth metal-metal bonds remains a challenge in the study of chemical bonds.Herein,we report the synthesis and characterization of a novel heteronuclear di-m...Comprehensive Summary The experimental investigation of rare-earth metal-metal bonds remains a challenge in the study of chemical bonds.Herein,we report the synthesis and characterization of a novel heteronuclear di-metallofullerene,ScY@C_(3v)(8)-C_(82),which contains a mixed rare-earth metal-metal bond.ScY@C_(3v)(8)-C_(82)was successfully synthesized by arc-discharging method and characterized by mass spectrometry,UV-vis-NIR spectroscopy and single-crystal X-ray diffraction crystallography,which unambiguously determined its molecular structure.Theoretical calculations were also performed to study the optimized positions of Sc-Y metallic dimer and the electronic configuration.The combined experimental and theoretical results confirmed that both Sc and Y atoms transfer two electrons to the C_(3v)(8)-C_(82)cage,i.e.,(ScY)4+@(C_(3v)(8)-C_(82))4-.In particular,a covalent Sc-Yσ2 bond,which has never been reported before,is proven to be formed inside C_(3v)(8)-C_(82)fullerene cage.This work presents a novel di-metallofullerene containing mixed rare-earth metal-metal bond and expands the understanding of metal-metal bonding of rare earth elements.展开更多
The platinum(II) terpyridyl acetylide complex [Pt(terpy)(C≡CR)]ClO4 (terpy=2,2'∶6'2''-terpyridine, R=CH2CH2CH3) (1) was incorporated into Nafion membranes. At high loading the dry membranes exhibit i...The platinum(II) terpyridyl acetylide complex [Pt(terpy)(C≡CR)]ClO4 (terpy=2,2'∶6'2''-terpyridine, R=CH2CH2CH3) (1) was incorporated into Nafion membranes. At high loading the dry membranes exhibit intense photoluminescence with max at 707 nm from the 3MMLCT state, which was not observed in fluid solution. Upon exposure to the vapor of polar volatile organic compounds (VOC), this photoluminescence was significantly red-shifed. This process was fully reversible when the VOC-incorporated membrane was dried in air. The dramatic and reversible changes in the emission spectra made the Nafion-supported complex as an interesting sensor candi-date for polar VOC.展开更多
基金Project(51625404)supported by the National Natural Science Foundation for Distinguished Young Scholar of ChinaProjects(51604104,51504295)supported by the National Natural Science Foundation of China
文摘In order to investigate the real-time cracking behavior of each component of a composite with strong interfacial bonding among lamellae, Ti-18 Nb(at.%) composite was prepared by spark plasma sintering(SPS), followed by hot-rolling, annealing, and quenching. The microstructure and mechanical properties were characterized by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), micro-region X-ray diffractometry(MRXRD), nanoindentation, and in-situ scanning electron microscopy tensile testing. The results show that the Ti-18 Nb consists of Ti-enriched, diffusion and Nb-enriched zones, and the sharp Nb gradient across different zones leads to inhomogeneous distribution of phase and mechanical properties. A remarkable finding is that the diffusion zones not only enable the cooperative deformation between the brittle Ti-enriched zones and the ductile Nb-enriched zones but also act as the crack-arresters to prevent the local cracks in the Ti-enriched zones from further propagating across the composite.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 50823003 and 90923018)
文摘The mechanism of contact electrification between metals was studied using the first-principles method, taking the Ag-Fe contact as an example. Charge population, charge density difference, the orbitals and densities of states （DOS） were calculated to study the electronic properties of the contacting interfacial atoms. Based on the calculation, the amount of contact charge was obtained. The investigation revealed that the electrons near Fermi levels with higher energies transfer between the outermost orbitals （s orbitals for Ag and d orbitals for Fe）. Meanwhile, polarized covalent bonds form between the d electrons in the deep energy states. These two effects together lead to an increase of charge magnitude at the interface. Also, the electrons responsible for electrification can be determined by their energies and orbitals.
基金supported by 973 Program (2006CB932900)National Natural Science Foundation of China (No. 20571074)Natural Science Foundation of Fujian Province (No. 2007J0172)
文摘The title complex cis-bis（tetrahydrothiophene）-bis（nitrate） platinum（H）, （tht）2Pt（NO3）2, was the reducing product from potassium hexachloroplatinate（IV） K2PtC16 where the platinum is tetra-valenced. Crystal data for CsH16N206PtS2： monoclinic, space group P21/c, a = 9.8833（5）, b = 8.6744（4）, c = 18.6407（9）A,β = 114.401（3）°, V = 1455.35（12）A3 Z = 4, Mr = 495.44, Dc = 2.261 g/cm3, F（000） = 944,μ = 9.950 mm-1, 2（MoKa） = 0.71073 A, T= 293（2） K, 2θmax = 54.96°, GOOF = 1.033, R = 0.0350 and wR = 0.0785 for 2572 observed reflections with I 〉 2σ（I）. X-ray diffraction studies reveal that the title complex has interesting weak metal-metal interactions and two molecules linked by metal-metal interaction exist as a group. Luminescent spectrum illuminates red emission of the complex at room temperature.
基金supported by the Natural Science Foundation of Shaanxi Province(No.2013JM2005)the National Science Council of China and the Full-Time Master Innovation Fund of Xi’an Shiyou University(No.2015cx140735)
文摘Molecular structure of a naphthyridine and pyrazine amine ligand, N2,N7-di（pyrazin-2-yl）-1,8-naphthyri-dine-2,7-diamine（H2dpznda 1） was studied, and a three-dimensional supramolecular network with a double helix chain structure through intermolecular hydrogen bonds and π-π interactions between the naphthyridine and pyrazine rings was depicted. Through ligand 1, [Co2（μ2-dpznda）2（μ2-CH3OH）2]（2） was obtained and two ligands coordinate to two Co2＋）as tetradentate bridging ligands. Single crystal and magnetism study on 2 revealed that the complex exhibited weak yet significant metal-metal interaction.
基金supported by the National Natural Science Foundation of China(Nos.92161102,21971118)the Natural Science Foundation of Tianjin City(Nos.21JCZXJC00140,20JCYBJC01560)the 111 Project(No.B18030)from Ministry of Education China
文摘We report here the synthesis and characterization of two new members of the M2 E 12 family of endohe-dral Zintl clusters,[Fe_(2)Sn_(4)Bi_(8)]^(3-)and[Cr_(2)Sb_(12)]^(3-),both of which contain open-shell metal dimers encap-sulated inside a triple-decker cluster of main-group atoms.The 75-electron[Fe_(2)Sn_(4)Bi_(8)]^(3-)cluster has a D4h-symmetric structure,while[Cr_(2)Sb_(12)]^(3-),despite having the same 75-electron count,is strongly dis-torted to a geometry that resembles a CrSb_(8)crown capped by a CrSb_(4)unit.The structural differences between the two are driven by the increasing availability of 3d electron density in the earlier transi-tion metal,which leads,ultimately,to different electronic configurations in the two clusters.The trends precisely mirror those observed in the ME_(10)and ME_(12)families containing a single transition metal ion.
基金supported by the National Natural Science Foundation of China(51872204,52072261 and 22011540379)the National Key Research and Development Program of China(2017YFA0204600)+1 种基金Shanghai Social Development Science and Technology Project(20dz1201800)Shanghai Sailing Program(21YF1430900).
文摘Co_(2)VO_(4) with Co tetrahedrons and octahedrons of transition metal oxides has achieved progress in electrocatalysts and batteries.However,high metal-metal interactions make it challenging to maintain high reactivity as well as increase the conductivity and stability of supercapacitors.In this work,spinel-structured CoZn_(0.5)V_(1.5)O_(4) with a high specific surface area was synthesized through an ion-exchange process from the metal-organic frameworks of zinc-cobalt.Density functional theory calculations indicate that the replacement of transition metal by Zn can decrease the interaction between the transition metals,leading to a downshift in the π^(∗)-orbitals(V-O)and half-filled a_(1g) orbitals near the Fermi level,thus increasing the conductivity and stability of CoZn_(0.5)V_(1.5)O_(4).As a supercapacitor electrode,CoZn_(0.5)V_(1.5)O_(4) exhibits high cycling durability(99.4% capacitance retention after 18,000 cycles)and specific capacitance(1100mFcm^(-2) at 1mAcm^(-2)).This work provides the possibility of designing octahedral and tetrahedral sites in transition metal oxides to improve their electrochemical performance.
文摘Many experimental results have shown that the property of amorphous alloys has certain relation with composition, because the change in composition can result in change in structure of amorphous alloys.So in order to understand the influence
基金the National Science Foundation China(NSFC No.52172051)the NSF of Jiangsu Province(BK20200041)+2 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)A.R.-F.and J.M.P.thank the Spanish Ministry of Science(grant PID2020-112762GB-I00 funded by MCIN/AEl/10.13039/501100011033)the Generalitat de Catalunya(grant 2021 SGR 00110)and the URV for support.
文摘Comprehensive Summary The experimental investigation of rare-earth metal-metal bonds remains a challenge in the study of chemical bonds.Herein,we report the synthesis and characterization of a novel heteronuclear di-metallofullerene,ScY@C_(3v)(8)-C_(82),which contains a mixed rare-earth metal-metal bond.ScY@C_(3v)(8)-C_(82)was successfully synthesized by arc-discharging method and characterized by mass spectrometry,UV-vis-NIR spectroscopy and single-crystal X-ray diffraction crystallography,which unambiguously determined its molecular structure.Theoretical calculations were also performed to study the optimized positions of Sc-Y metallic dimer and the electronic configuration.The combined experimental and theoretical results confirmed that both Sc and Y atoms transfer two electrons to the C_(3v)(8)-C_(82)cage,i.e.,(ScY)4+@(C_(3v)(8)-C_(82))4-.In particular,a covalent Sc-Yσ2 bond,which has never been reported before,is proven to be formed inside C_(3v)(8)-C_(82)fullerene cage.This work presents a novel di-metallofullerene containing mixed rare-earth metal-metal bond and expands the understanding of metal-metal bonding of rare earth elements.
基金Project supported by the Ministry of Science and Technology of China (Nos. G2000078104 G2000077502) and the National Natural Science Foun-dation of China and Bureau for the Basic Research of Chinese Academy of Sciences.
文摘The platinum(II) terpyridyl acetylide complex [Pt(terpy)(C≡CR)]ClO4 (terpy=2,2'∶6'2''-terpyridine, R=CH2CH2CH3) (1) was incorporated into Nafion membranes. At high loading the dry membranes exhibit intense photoluminescence with max at 707 nm from the 3MMLCT state, which was not observed in fluid solution. Upon exposure to the vapor of polar volatile organic compounds (VOC), this photoluminescence was significantly red-shifed. This process was fully reversible when the VOC-incorporated membrane was dried in air. The dramatic and reversible changes in the emission spectra made the Nafion-supported complex as an interesting sensor candi-date for polar VOC.
