A microfluidic system was developed for the synthesis of trigonal selenium（t-Se） nanowires, which was composed of a glass microchip coupled with a poly（methyl methacrylate）（PMMA） microchip. In the glass microchi...A microfluidic system was developed for the synthesis of trigonal selenium（t-Se） nanowires, which was composed of a glass microchip coupled with a poly（methyl methacrylate）（PMMA） microchip. In the glass microchip, amorphous selenium（a-Se） colloid was prepared by reducing selenious acid with an excess amount of hydrazine at a temperature of 100 ℃. In the coupled PMMA microchip, a-Se was transformed into more stable t-Se seeds via sonication at room temperature. The residence time of the reactants in both microchips was optimized by varying the dimension and length of the microchannel each. The t-Se nanowires were formed by anisotropic growth of selenium crystallite during sonication and aging under the assistance of β-cyclodextrin（β-CD）. Various stages of the nanowires＇ growth were investigated. The as-synthesized products were characterized by powder X-Ray diffraction（XRD）, Raman spectroscopy, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and selected-area electron diffraction（SAED）.展开更多
A new heptanuclear trigonal prismatic cluster [PrCu6(μ3-OH)3(Gly)6im6](ClO4)6 was synthesized through the self-assembly of Pr3+, Cu2+, glycine and imidazole in aqueous solution and characterized by X-ray structure ...A new heptanuclear trigonal prismatic cluster [PrCu6(μ3-OH)3(Gly)6im6](ClO4)6 was synthesized through the self-assembly of Pr3+, Cu2+, glycine and imidazole in aqueous solution and characterized by X-ray structure analysis. The compound belongs to the trigonal R3 space group with a = b = 15.8761(2), c = 23.4943(5) ?, V = 5128.4(1) ?3, Z = 3, Dc = 1.965 g/cm3, μ = 2.869 mm-1, F(000) = 3012, the final R = 0.0332 and wR = 0.0844 for 3596 independent reflections. In the cation, the Pr3+ ion is situated at the center of a prism formed by six copper atoms and coordinates to nine oxygen atoms with a tricapped trigonal prismatic coordination polyhedron. Six glycine ligands and six imidazole terminal ligands participate in constructing the cluster.展开更多
With the non-equilibrium Green’s function method and density functional theory, we have studied the electronic properties of trigonal graphene nanoribbons, with Fe terminal and H terminal, coupled to gold electrodes....With the non-equilibrium Green’s function method and density functional theory, we have studied the electronic properties of trigonal graphene nanoribbons, with Fe terminal and H terminal, coupled to gold electrodes. Rectification behavior can be observed when the electrode-molecule contact distance is larger than 2.2 Å. The electronic transport is greatly improved in case of Fe terminal which is analyzed in terms of transmission spectra and density of states.展开更多
Hybrid perovskites have attracted enormous attention in the next generation resistive switching(RS)memristor for the artificial synapses,owing to their ambipolar charge transport,long diffusion length,and tunable visi...Hybrid perovskites have attracted enormous attention in the next generation resistive switching(RS)memristor for the artificial synapses,owing to their ambipolar charge transport,long diffusion length,and tunable visible bandgap.However,the variable switch,limited reproducibility,and poor endurance are the obstacles to the practical application of the perovskite memristors.Herein,we reported a multilevel RS nonvolatile memory based on a 3D trigonal HC(NH_(2))_(2)PbI_(3)(α‐FAPbI_(3))perovskite layer modified by 1‐cyanobutyl‐3‐methylimidazolium chloride([CNBmim]Cl)and sandwiched between ITO and Au electrodes(Au/[CNBmim]Cl/α‐FAPbI_(3)/SnO_(2)/ITO).In contrast to the bare memristor with failure switching from low resistance state(LRS)to high resistance state(HRS),the memristor device based on theα‐FAPbI_(3) modified with[CNBmim]Cl(Target device)shows the retention time over 10^(4) s with On/Off ratio(>10^(2))and endurance up to 550 cycles.The stable RS cycle benefits from the accelerated electrons de‐trapping from the reduced defects and fast charge separation in the interface ofα‐FAPbI_(3)/electrode,leading to the rupture of conductive filaments and transition of LRS to HRS.As a two‐terminal analog synaptic device,the target device can realize random handwritten digit recognition with an impressive accuracy of 89.3%on the condition of low learning phases(500 training cycles).展开更多
α-RuCl_(3)is a tantalizing playground to search for the quantum spin liquid states with leading Kitaev term due to the conformation of Jackeli-Khaliullin mechanism.Suppressing the non-Kitaev interaction to approach t...α-RuCl_(3)is a tantalizing playground to search for the quantum spin liquid states with leading Kitaev term due to the conformation of Jackeli-Khaliullin mechanism.Suppressing the non-Kitaev interaction to approach the Kitaev limit is the major objective in the experimental design of Kitaev-Jackeli-Khaliullin materials,for which the practical feasibility rests on the manipulation of the exact crystalline structure.A tensile strain,leading to the further compressive trigonal field splitting which would alter the spin-orbital entangled character and tune the intrinsic hopping exchanges,has been widely proposed as the promising strategy to enhance the comparative Kitaev interaction.In this work,we preform in-depth Scan Tunneling Microscope study on the electronic patterns of strainedα-RuCl_(3)monolayer on graphite substrate.Based on Chen’s derivative rule,a further trigonal field splitting is identified by analyzing the lateral-gradient imaging effect caused by an anisotropic tip.A spatial variation of the magnitude of trigonal crystal field due to the slight inhomogeneity of strain accords with the orbital polarization near the Mott gap.All evidences point to the facts that the compressive trigonal crystal field in the stretchedα-RuCl_(3)monolayer lifts the degeneracy of t2g states with higher eg and lower a1g orbitals,and the Coulomb interactions of the eg orbitals take the main responsibility for the Mott effect.展开更多
By allowing H_(2)SeO_(4),Cy_(2)NH,CyNH_(2) or Bz2NH to react respectively with SnPh_(3)Cl(in methanol),SnPh_(2)Cl_(2)(in water+methanol)and MgCl_(2)·6H_(2)O(in methanol)in specific ratios,the studied complexes ar...By allowing H_(2)SeO_(4),Cy_(2)NH,CyNH_(2) or Bz2NH to react respectively with SnPh_(3)Cl(in methanol),SnPh_(2)Cl_(2)(in water+methanol)and MgCl_(2)·6H_(2)O(in methanol)in specific ratios,the studied complexes are obtained.The suggested structures are discrete and polymer,the environment of the tin center being trans trigonal bipyramidal(compound 1),tetrahedral(compound 2)and octahedral(compound 3),the anions behaving as a bidentate selenate.展开更多
One new hydrogenosuccinate and two succinate adduct and complex have been synthesized and studied by infrared,UV-Visible and NMR(Nuclear Magnetic Resonance Spectroscopy)^(119)Sn spectroscopies.The suggested structure ...One new hydrogenosuccinate and two succinate adduct and complex have been synthesized and studied by infrared,UV-Visible and NMR(Nuclear Magnetic Resonance Spectroscopy)^(119)Sn spectroscopies.The suggested structure is discrete,the hydrogenosuccinate behaving as a monodentate ligand or only involved in hydrogen bonding,the environment around the magnesium centre being triangular(compound 3).The succiate anion is a monochelating ligand(compound 1 and 2).In all the suggested structures,when extra hydrogen bonds are considered,supramolecular architectures are obtained(compound 2 and 3).展开更多
The electron paramagnetic resonance spectra of trigonal Mn^(2+)centers in ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)crystals are studied on the basis of the complete energy matrices for a d5 configuration ...The electron paramagnetic resonance spectra of trigonal Mn^(2+)centers in ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)crystals are studied on the basis of the complete energy matrices for a d5 configuration ion in a trigonal ligand field.It is demonstrated that the local lattice structure around a trigonal Mn2+center has an elongation distortion along the crystalline c3 axis,and when Mn2+is doped in the ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)crystals,there is a similar local distortion.From the EPR calculation,the local lattice structure parameters for trigonal Mn2+centers in ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)are determined.展开更多
The complex Fe(aapo)2Cl3 with chemical formula C14H16Cl3FeN4O4 was obtained by the reaction of FeCl36H2O with apoHCl (apo = 2璦mino pyridine N璷xide) in acetonitrile. The result shows that CH3CN has been hydrolysised ...The complex Fe(aapo)2Cl3 with chemical formula C14H16Cl3FeN4O4 was obtained by the reaction of FeCl36H2O with apoHCl (apo = 2璦mino pyridine N璷xide) in acetonitrile. The result shows that CH3CN has been hydrolysised with the water from FeCl36H2O dissolving, and then the hydrolysised product condenses with apo to give aapo. A single-crystal X璻ay study of Fe(aapo)2Cl3 shows it belongs to the monoclinic system, space group C2/c with a = 15.873(3), b = 10.322(2), c = 11.987(2) ? b = 106.35(1), V = 1884.5(6) 3, Z = 4, Mr = 466.51, Dc = 1.644 g/cm3, m(MoKa) = 1.253 mm-1, F(000) = 948, R = 0.0377 and wR = 0.0749 for 1262 observed reflections with I > 2(I). Fe (Ⅲ) is coordinated by a trigonal bipyramidal geometry with three chlorine atoms lying on the equatorial plane and two oxygen atoms connected with the nitrogen atoms of pyridine rings occupying the axial positions, while the iron and Cl(1) atoms lie on the crystallographic 2-fold axis. The dihedral angle of two pyridine rings is 71.74(9). There exist N(2)H(2)…O(1)?hydrogen bonds in the crystal structure.展开更多
The title crystal of 2-germatranylmethyl-N- (4'-methylphenyl)succinimide (C18H24GeN2O5) was determined by single crystal X-ray diffraction- The crystalbelongs to the orthorhombic system, space group P212121 with M...The title crystal of 2-germatranylmethyl-N- (4'-methylphenyl)succinimide (C18H24GeN2O5) was determined by single crystal X-ray diffraction- The crystalbelongs to the orthorhombic system, space group P212121 with Mr = 420. 99, a= 6. 716(1), b=22- 860(8), c= 11. 891 (3) A, V= 1826(1) A3, Z=4,Dx= 1. 53 Mg. m-3,A= 0. 71073A, μ= 1. 684 mm-l, and F(000) =872. The structure was solved by direct methods. The final refinement is converged with unweighted and weighted agreement factors of 0. 047 and 0. 064 for 1610 observed reflections with I≥3δ(I). The results of structure analysis indicate that the framework of this five-coordinated germanium compound is a distorted trigonal bipyramid(TBP).展开更多
We designed and optimized a large number of the isomers of Si12＋ at the level of density functional theory （DFT）-B3LYP/6-311＋＋G（d） using the Gaussian 03 software package. An unambiguous structure of the Si12＋ ...We designed and optimized a large number of the isomers of Si12＋ at the level of density functional theory （DFT）-B3LYP/6-311＋＋G（d） using the Gaussian 03 software package. An unambiguous structure of the Si12＋ cluster is presented, whose IR spectrum agrees well with the experiment result. The most stable geometric structures of Gen＋（n=2―15） clusters were determined by the all-electron PBE/DND method in DMol3 of the Material Studio Package, and compared with those of the corresponding Sin＋ geometries. Most structures of Gen＋ and Sin＋ are similar except the ones of those for n=9, 12, 13 and 14, and the pentagonal bipyramid motif and the tri-capped trigonal prism（TTP） motif often appear in the Sin＋ and Gen＋（n=7―15） structures（except for Si14＋）.展开更多
Crystal of barium boric oxide(BBO) crystallizes in trigollal system. Imperfections in two specimens of(001)plates (one being transparent and the other containing inclusions)in the crystals have been identified by X-ra...Crystal of barium boric oxide(BBO) crystallizes in trigollal system. Imperfections in two specimens of(001)plates (one being transparent and the other containing inclusions)in the crystals have been identified by X-ray topography.展开更多
We present the first findings of the new electrically- and optically-detected magnetic resonance technique [ED electron spin resonance (EDESR) and (ODMR)] which reveal single point defects in the ultra-narrow silicon ...We present the first findings of the new electrically- and optically-detected magnetic resonance technique [ED electron spin resonance (EDESR) and (ODMR)] which reveal single point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor δ-barriers. This technique allows the ESR identification without the application of the external cavity as well as a high frequency source and recorder, with measuring the only magnetoresistance (EDESR) and transmission (ODMR) spectra within frameworks of the excitonic normal-mode coupling (NMC) caused by the microcavities embedded in the Si-QW plane. The new resonant positive magnetoresistance data are interpreted here in terms of the interference transition in the diffusive transport of free holes respectively between the weak antilocalization regime in the region far from the ESR of a paramagnetic point defect located inside or near the conductive channel and the weak localization regime in the nearest region of the ESR of that defect.展开更多
We consider the AB-(Bernal) stacking for the bi-layer graphene (BLG) system and assume that a perpendicular electric field is created by the external gates deposited on the BLG surface. In the basis (A1, B2, A2, B1) f...We consider the AB-(Bernal) stacking for the bi-layer graphene (BLG) system and assume that a perpendicular electric field is created by the external gates deposited on the BLG surface. In the basis (A1, B2, A2, B1) for the valleyKand the basis (B2, A1, B1, A2) for the valley K′, we show the occurrence of trigonal warping [1], that is, splitting of the energy bands or the density of states on the kx - ky plane into four pockets comprising of the central part and three legs due to a (skew) interlayer hopping between A1 and B2. The hopping between A1 - B2 leads to a concurrent velocity v3 in addition to the Fermi velocity vF. Our noteworthy outcome is that the above-mentioned topological change, referred to as the Lifshitz transition [2, 3], is entirely bias-tunable. Furthermore, the many-body effects, which is known to yield logarithmic renormalizations [4] in the band dispersions of monolayer graphene, is found to have significant effect on the bias-tunability of this transition. We also consider a variant of the system where the A atoms of the two layers are over each other and the B atoms of the layers are displaced with respect to each other. The Fermi energy density of statesfor zero bias corresponds to the inverted sombrero-like structure. The structure is found to get deformed due to the increase in the bias.展开更多
A new zero-dimensional（0D） thioborate compound Ba（13）（BS3）6（SnS6）, the first one in the AE/B/Sn/Q（AE=alkali-earth metals; Q=S, Se, Te） family, has been synthesized by conventional high-temperature solid-stat...A new zero-dimensional（0D） thioborate compound Ba（13）（BS3）6（SnS6）, the first one in the AE/B/Sn/Q（AE=alkali-earth metals; Q=S, Se, Te） family, has been synthesized by conventional high-temperature solid-state reaction. It crystallizes in the trigonal space group of R3（No. 148） with a=b=21.4634（6） , c=8.3653（5） , V=3337.4（2） 3, Z=3, Mr=2738.41, Dc=4.088 g/cm3, μ=12.977 mm（-1）, F（000）=3576, the final R=0.0208 and w R=0.0505 with I 〉 2σ（I）, 3.28〈θ〈27.49°, w=1/[σ2（Fo2） ＋（0.0253P）2 ＋ 0.0000P], where P =（Fo2 ＋ 2Fc2）/3, S=1.051,（Δρ）max=0.639 and（Δρ）min=–1.195 e/3. The structure is constructed by discrete [BS3]（3–） trigonal planes and isolated [SnS6]（8–） octahedra with Ba（2＋） cations filled among them. The IR spectrum indicates the presence of lighter element boron. Its optical band gap shown by the UV-Vis-near-IR spectrum is about 2.69 e V, which agrees well with the electronic structure calculation.展开更多
基金Supported by the Natural Science Foundation of Zhejiang Province,China(No.Z407029)the Hangzhou Qianjiang Scholar Foundation,China(No.HZ2010-41)
文摘A microfluidic system was developed for the synthesis of trigonal selenium（t-Se） nanowires, which was composed of a glass microchip coupled with a poly（methyl methacrylate）（PMMA） microchip. In the glass microchip, amorphous selenium（a-Se） colloid was prepared by reducing selenious acid with an excess amount of hydrazine at a temperature of 100 ℃. In the coupled PMMA microchip, a-Se was transformed into more stable t-Se seeds via sonication at room temperature. The residence time of the reactants in both microchips was optimized by varying the dimension and length of the microchannel each. The t-Se nanowires were formed by anisotropic growth of selenium crystallite during sonication and aging under the assistance of β-cyclodextrin（β-CD）. Various stages of the nanowires＇ growth were investigated. The as-synthesized products were characterized by powder X-Ray diffraction（XRD）, Raman spectroscopy, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and selected-area electron diffraction（SAED）.
基金This research was supported by the State Key Laboratory of Structural Chemistry the National Science and Technology of China (001CB1089)+8 种基金 the Chinese Academy of Sciences (CAS) the National Science Foundation of China (20333070 2027307390206040) and the Science Foundation of CAS and Fujian Province (2002F0142003J0422004J0412004H201-1)
文摘A new heptanuclear trigonal prismatic cluster [PrCu6(μ3-OH)3(Gly)6im6](ClO4)6 was synthesized through the self-assembly of Pr3+, Cu2+, glycine and imidazole in aqueous solution and characterized by X-ray structure analysis. The compound belongs to the trigonal R3 space group with a = b = 15.8761(2), c = 23.4943(5) ?, V = 5128.4(1) ?3, Z = 3, Dc = 1.965 g/cm3, μ = 2.869 mm-1, F(000) = 3012, the final R = 0.0332 and wR = 0.0844 for 3596 independent reflections. In the cation, the Pr3+ ion is situated at the center of a prism formed by six copper atoms and coordinates to nine oxygen atoms with a tricapped trigonal prismatic coordination polyhedron. Six glycine ligands and six imidazole terminal ligands participate in constructing the cluster.
文摘With the non-equilibrium Green’s function method and density functional theory, we have studied the electronic properties of trigonal graphene nanoribbons, with Fe terminal and H terminal, coupled to gold electrodes. Rectification behavior can be observed when the electrode-molecule contact distance is larger than 2.2 Å. The electronic transport is greatly improved in case of Fe terminal which is analyzed in terms of transmission spectra and density of states.
基金The authors are grateful for financial support from the National Natural Science Foundation of China(No.11874143)the Natural Science Foundation of Hubei Province(No.2022CFB402)+1 种基金Science and Technology Major Project of Hubei(No.2022AEA001)the Application Fundamental Research Project of Wuhan Science and Technology Bureau(No.2019010701011396).
文摘Hybrid perovskites have attracted enormous attention in the next generation resistive switching(RS)memristor for the artificial synapses,owing to their ambipolar charge transport,long diffusion length,and tunable visible bandgap.However,the variable switch,limited reproducibility,and poor endurance are the obstacles to the practical application of the perovskite memristors.Herein,we reported a multilevel RS nonvolatile memory based on a 3D trigonal HC(NH_(2))_(2)PbI_(3)(α‐FAPbI_(3))perovskite layer modified by 1‐cyanobutyl‐3‐methylimidazolium chloride([CNBmim]Cl)and sandwiched between ITO and Au electrodes(Au/[CNBmim]Cl/α‐FAPbI_(3)/SnO_(2)/ITO).In contrast to the bare memristor with failure switching from low resistance state(LRS)to high resistance state(HRS),the memristor device based on theα‐FAPbI_(3) modified with[CNBmim]Cl(Target device)shows the retention time over 10^(4) s with On/Off ratio(>10^(2))and endurance up to 550 cycles.The stable RS cycle benefits from the accelerated electrons de‐trapping from the reduced defects and fast charge separation in the interface ofα‐FAPbI_(3)/electrode,leading to the rupture of conductive filaments and transition of LRS to HRS.As a two‐terminal analog synaptic device,the target device can realize random handwritten digit recognition with an impressive accuracy of 89.3%on the condition of low learning phases(500 training cycles).
基金the National Key Research and Development Program of China(Grant No.2019YFA0308404)Science and Technology Commission of Shanghai Municipality(Grant No.20JC1415900)+3 种基金Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)support from the National Natural Science Foundation of China(Grants No.12174062)sponsored by Shanghai Pujiang Program No.19PJ1401000National Natural Science Foundation of China(Grant No.12004076).
文摘α-RuCl_(3)is a tantalizing playground to search for the quantum spin liquid states with leading Kitaev term due to the conformation of Jackeli-Khaliullin mechanism.Suppressing the non-Kitaev interaction to approach the Kitaev limit is the major objective in the experimental design of Kitaev-Jackeli-Khaliullin materials,for which the practical feasibility rests on the manipulation of the exact crystalline structure.A tensile strain,leading to the further compressive trigonal field splitting which would alter the spin-orbital entangled character and tune the intrinsic hopping exchanges,has been widely proposed as the promising strategy to enhance the comparative Kitaev interaction.In this work,we preform in-depth Scan Tunneling Microscope study on the electronic patterns of strainedα-RuCl_(3)monolayer on graphite substrate.Based on Chen’s derivative rule,a further trigonal field splitting is identified by analyzing the lateral-gradient imaging effect caused by an anisotropic tip.A spatial variation of the magnitude of trigonal crystal field due to the slight inhomogeneity of strain accords with the orbital polarization near the Mott gap.All evidences point to the facts that the compressive trigonal crystal field in the stretchedα-RuCl_(3)monolayer lifts the degeneracy of t2g states with higher eg and lower a1g orbitals,and the Coulomb interactions of the eg orbitals take the main responsibility for the Mott effect.
文摘By allowing H_(2)SeO_(4),Cy_(2)NH,CyNH_(2) or Bz2NH to react respectively with SnPh_(3)Cl(in methanol),SnPh_(2)Cl_(2)(in water+methanol)and MgCl_(2)·6H_(2)O(in methanol)in specific ratios,the studied complexes are obtained.The suggested structures are discrete and polymer,the environment of the tin center being trans trigonal bipyramidal(compound 1),tetrahedral(compound 2)and octahedral(compound 3),the anions behaving as a bidentate selenate.
基金Plasseraud,ICMUB UMR CNRS 6302,University of Burgundy,Faculty of Sciences,Dijon,France.
文摘One new hydrogenosuccinate and two succinate adduct and complex have been synthesized and studied by infrared,UV-Visible and NMR(Nuclear Magnetic Resonance Spectroscopy)^(119)Sn spectroscopies.The suggested structure is discrete,the hydrogenosuccinate behaving as a monodentate ligand or only involved in hydrogen bonding,the environment around the magnesium centre being triangular(compound 3).The succiate anion is a monochelating ligand(compound 1 and 2).In all the suggested structures,when extra hydrogen bonds are considered,supramolecular architectures are obtained(compound 2 and 3).
基金by the National Natural Science Foundation under Grant No 10374068the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20050610011.
文摘The electron paramagnetic resonance spectra of trigonal Mn^(2+)centers in ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)crystals are studied on the basis of the complete energy matrices for a d5 configuration ion in a trigonal ligand field.It is demonstrated that the local lattice structure around a trigonal Mn2+center has an elongation distortion along the crystalline c3 axis,and when Mn2+is doped in the ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)crystals,there is a similar local distortion.From the EPR calculation,the local lattice structure parameters for trigonal Mn2+centers in ZnNbOF_(5)·6(H_(2)O)and CoNbOF_(5)·6(H_(2)O)are determined.
基金the Natural Science Foundation of Xuzhou Normal University (01BXL009)
文摘The complex Fe(aapo)2Cl3 with chemical formula C14H16Cl3FeN4O4 was obtained by the reaction of FeCl36H2O with apoHCl (apo = 2璦mino pyridine N璷xide) in acetonitrile. The result shows that CH3CN has been hydrolysised with the water from FeCl36H2O dissolving, and then the hydrolysised product condenses with apo to give aapo. A single-crystal X璻ay study of Fe(aapo)2Cl3 shows it belongs to the monoclinic system, space group C2/c with a = 15.873(3), b = 10.322(2), c = 11.987(2) ? b = 106.35(1), V = 1884.5(6) 3, Z = 4, Mr = 466.51, Dc = 1.644 g/cm3, m(MoKa) = 1.253 mm-1, F(000) = 948, R = 0.0377 and wR = 0.0749 for 1262 observed reflections with I > 2(I). Fe (Ⅲ) is coordinated by a trigonal bipyramidal geometry with three chlorine atoms lying on the equatorial plane and two oxygen atoms connected with the nitrogen atoms of pyridine rings occupying the axial positions, while the iron and Cl(1) atoms lie on the crystallographic 2-fold axis. The dihedral angle of two pyridine rings is 71.74(9). There exist N(2)H(2)…O(1)?hydrogen bonds in the crystal structure.
文摘The title crystal of 2-germatranylmethyl-N- (4'-methylphenyl)succinimide (C18H24GeN2O5) was determined by single crystal X-ray diffraction- The crystalbelongs to the orthorhombic system, space group P212121 with Mr = 420. 99, a= 6. 716(1), b=22- 860(8), c= 11. 891 (3) A, V= 1826(1) A3, Z=4,Dx= 1. 53 Mg. m-3,A= 0. 71073A, μ= 1. 684 mm-l, and F(000) =872. The structure was solved by direct methods. The final refinement is converged with unweighted and weighted agreement factors of 0. 047 and 0. 064 for 1610 observed reflections with I≥3δ(I). The results of structure analysis indicate that the framework of this five-coordinated germanium compound is a distorted trigonal bipyramid(TBP).
基金Supported by the National Natural Science Foundation of China(Nos.20773047 and 21043001)
文摘We designed and optimized a large number of the isomers of Si12＋ at the level of density functional theory （DFT）-B3LYP/6-311＋＋G（d） using the Gaussian 03 software package. An unambiguous structure of the Si12＋ cluster is presented, whose IR spectrum agrees well with the experiment result. The most stable geometric structures of Gen＋（n=2―15） clusters were determined by the all-electron PBE/DND method in DMol3 of the Material Studio Package, and compared with those of the corresponding Sin＋ geometries. Most structures of Gen＋ and Sin＋ are similar except the ones of those for n=9, 12, 13 and 14, and the pentagonal bipyramid motif and the tri-capped trigonal prism（TTP） motif often appear in the Sin＋ and Gen＋（n=7―15） structures（except for Si14＋）.
文摘Crystal of barium boric oxide(BBO) crystallizes in trigollal system. Imperfections in two specimens of(001)plates (one being transparent and the other containing inclusions)in the crystals have been identified by X-ray topography.
文摘We present the first findings of the new electrically- and optically-detected magnetic resonance technique [ED electron spin resonance (EDESR) and (ODMR)] which reveal single point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor δ-barriers. This technique allows the ESR identification without the application of the external cavity as well as a high frequency source and recorder, with measuring the only magnetoresistance (EDESR) and transmission (ODMR) spectra within frameworks of the excitonic normal-mode coupling (NMC) caused by the microcavities embedded in the Si-QW plane. The new resonant positive magnetoresistance data are interpreted here in terms of the interference transition in the diffusive transport of free holes respectively between the weak antilocalization regime in the region far from the ESR of a paramagnetic point defect located inside or near the conductive channel and the weak localization regime in the nearest region of the ESR of that defect.
文摘We consider the AB-(Bernal) stacking for the bi-layer graphene (BLG) system and assume that a perpendicular electric field is created by the external gates deposited on the BLG surface. In the basis (A1, B2, A2, B1) for the valleyKand the basis (B2, A1, B1, A2) for the valley K′, we show the occurrence of trigonal warping [1], that is, splitting of the energy bands or the density of states on the kx - ky plane into four pockets comprising of the central part and three legs due to a (skew) interlayer hopping between A1 and B2. The hopping between A1 - B2 leads to a concurrent velocity v3 in addition to the Fermi velocity vF. Our noteworthy outcome is that the above-mentioned topological change, referred to as the Lifshitz transition [2, 3], is entirely bias-tunable. Furthermore, the many-body effects, which is known to yield logarithmic renormalizations [4] in the band dispersions of monolayer graphene, is found to have significant effect on the bias-tunability of this transition. We also consider a variant of the system where the A atoms of the two layers are over each other and the B atoms of the layers are displaced with respect to each other. The Fermi energy density of statesfor zero bias corresponds to the inverted sombrero-like structure. The structure is found to get deformed due to the increase in the bias.
基金supported by the National Natural Science Foundation of China(21233009,21225104,91422303,21301175 and 21171168)
文摘A new zero-dimensional（0D） thioborate compound Ba（13）（BS3）6（SnS6）, the first one in the AE/B/Sn/Q（AE=alkali-earth metals; Q=S, Se, Te） family, has been synthesized by conventional high-temperature solid-state reaction. It crystallizes in the trigonal space group of R3（No. 148） with a=b=21.4634（6） , c=8.3653（5） , V=3337.4（2） 3, Z=3, Mr=2738.41, Dc=4.088 g/cm3, μ=12.977 mm（-1）, F（000）=3576, the final R=0.0208 and w R=0.0505 with I 〉 2σ（I）, 3.28〈θ〈27.49°, w=1/[σ2（Fo2） ＋（0.0253P）2 ＋ 0.0000P], where P =（Fo2 ＋ 2Fc2）/3, S=1.051,（Δρ）max=0.639 and（Δρ）min=–1.195 e/3. The structure is constructed by discrete [BS3]（3–） trigonal planes and isolated [SnS6]（8–） octahedra with Ba（2＋） cations filled among them. The IR spectrum indicates the presence of lighter element boron. Its optical band gap shown by the UV-Vis-near-IR spectrum is about 2.69 e V, which agrees well with the electronic structure calculation.
