We have reported new magnetic and optical properties of Mn2O3 nanostructures. The nanostructures have been synthesized by the hydrothermal method combined with the adjustment of pH values in the reaction system. The p...We have reported new magnetic and optical properties of Mn2O3 nanostructures. The nanostructures have been synthesized by the hydrothermal method combined with the adjustment of pH values in the reaction system. The particular characteristics of the nanostructures have been analyzed by employing X-Ray diffraction （XRD）, scanning electron microscopy （SEM）, energy dispersive X-ray （EDX） analysis, transmission electron microscopy （TEM）, high resolution transmission electron microscopy （HRTEM）, Raman spectroscopy （RS）, UV-visible spectroscopy, and the vibrating sample magnetometer （VSM）. Structural investigation manifests that the synthesized Mn2O3 nanostructures are orthorhombic crystal. Magnetic investigation indicates that the Mn2O3 nanostructures are antiferromagnetic and the antiferromagnetic transition temperature is at TN = 83 K. Furthermore, the Mn2O3 nanostructures possess canted antiferromagnetic order below the Neel temperature due to spin frustration, resulting in hysteresis with large coercivity （1580 Oe） and remnant magnetization （1.52 emu/g）. The UV-visible spectrophotometry was used to determine the transmittance behaviour of Mn203 nanostructures. A direct optical band gap of 1.2 eV was acquired by using the Davis-Mott model. The UV-visible spectrum indicates that the absorption is prominent in the visible region, and transparency is more than 80% in the UV region.展开更多
A new three-dimensional nickel（Ⅱ） hydrogen-bonded molecular self assembly containing [（Ni（nicotinamide）2（thiocyanate）2（H2O）2] complex has been synthesized and characterized by single-crystal X-ray diffractio...A new three-dimensional nickel（Ⅱ） hydrogen-bonded molecular self assembly containing [（Ni（nicotinamide）2（thiocyanate）2（H2O）2] complex has been synthesized and characterized by single-crystal X-ray diffraction,FTIR spectroscopy,thermal analysis and magnetic measurements.Structural analysis reveals that the complex crystallizes in triclinic space group P1（crystal data a = 7.5574,b = 8.2683,c = 9.0056 A,α = 73.010,β = 69.698,γ = 66.51） and exhibits a distorted octahedral coordination sphere.Most interesting point in its structure is the involvement of sulphur atom of thiocyanate moiety in the trifurcated hydrogen bonding to build up the hydrogen-bonded self assembly.The magnetic behavior as determined by squid magnetometer（2~300 K temp.range） reveals dominating antiferromagnetic interaction followed by spin canting behavior below 20 K.展开更多
High quality single crystal CaFe4As3 was grown by using the Sn flux method. Unlike layered CaFe2As2, CaFe4As3 crystallizes in an orthorhombic three-dimensional structure. Two magnetic ordering transitions are observed...High quality single crystal CaFe4As3 was grown by using the Sn flux method. Unlike layered CaFe2As2, CaFe4As3 crystallizes in an orthorhombic three-dimensional structure. Two magnetic ordering transitions are observed at - 90 K and - 27 K, respectively. The high temperature transition is an antiferromagnetic（AF） ordering transition. However, the low temperature transition shows complex properties. It shows a ferromagnetic-like transition when a field is applied along b-axis, while antiferromagnetism-like transition when a field is applied perpendicular to b-axis. These results suggest that the low temperature transition at 27 K is a first-order transition from an AF state to a canted AF state. In addition, the low temperature electron specific heat coefficient reaches as high as 143 mJ/mol.K2, showing a heavy fermion behavior.展开更多
By using the derivative method, we obtained the same result with that of the previous work of Chen et al. in 2006. Different from the integral form, the derivative form of the surface expression published in this pape...By using the derivative method, we obtained the same result with that of the previous work of Chen et al. in 2006. Different from the integral form, the derivative form of the surface expression published in this paper is derived from differential equation and based on the theory of non-imaging focusing heliostat proposed by Chen et al. in 2001. The comparison of the derivative form of fixed aberration correction surface has been made with that of integral form surface as well as that of spherical surface in concentrating the solar ray.展开更多
Based on the bent ligand 1 H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole(3,4?-Hbpt) with Co(Ⅱ) ions as well as a series of polycarboxylate co-ligands, three new coordination polymers were yielded, namely, {[Co(op)(3,4...Based on the bent ligand 1 H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole(3,4?-Hbpt) with Co(Ⅱ) ions as well as a series of polycarboxylate co-ligands, three new coordination polymers were yielded, namely, {[Co(op)(3,4?-Hbpt)(H_2O)_3]?2 H_2O}n(1), [Co(cyc)(3,4′-Hbpt)(H_2O)]n(2) and [Co(pro)(3,4′-Hbpt)(H_2O)]n(3)(here, op = o-phthalic anion, cyc = 1,1-cyclobutanedicarboxylic anion, pro = propanedioic anion). In cooperation with the auxiliary polycarboxylate co-ligands, a variety of Co(Ⅱ) coordination networks, such as 1-D chain 1 and 2-D layer 2 and 3 have been assembled. The magnetic behaviors of compounds 1～3 were studied. All of them indicated the existence of interesting spin-canting behavior.展开更多
The Heisenberg-Kitaev(HK)model on various lattices has attracted a lot of attention because it may lead to exotic states such as quantum spin liquid and topological orders.The rare-earth-based kagome lattice(KL)compou...The Heisenberg-Kitaev(HK)model on various lattices has attracted a lot of attention because it may lead to exotic states such as quantum spin liquid and topological orders.The rare-earth-based kagome lattice(KL)compounds Mg_(2)RE_(3)Sb_(3)O_(14)(RE=Gd,Er)and(RE=Nd)have q=0,120°order and canted ferromagnetic(CFM)order,respectively.Interestingly,the HK model on the KL has the same ground state long-range orders.In the theoretical phase diagram,the CFM phase resides in a continuous parameter region and there is no phase change across special parameter points,such as the Kitaev ferromagnetic(KFM)point,the ferromagnetic(FM)point and its dual FM point.However,a ground state property cannot distinguish a system with or without topological nontrivial excitations and related phase transitions.Here,we study the topological magnon excitations and related thermal Hall conductivity in the HK model on the KL with CFM order.The CFM phase can be divided into two regions related by the Klein duality,with the self dual KFM point as their boundary.We find that the scalar spin chirality,which is intrinsic in the CFM order,changes sign across the KFM point.This leads to the opposite Chem numbers of corresponding magnon bands in the two regions,and also the sign change of the magnon thermal Hall conductivity.展开更多
Analyses of the new slender-ship theory of wave resistance were made and corresponding calculation methods were proposed. Based on these theoretical methods, the calculations of wave resistance of near surface submers...Analyses of the new slender-ship theory of wave resistance were made and corresponding calculation methods were proposed. Based on these theoretical methods, the calculations of wave resistance of near surface submersible, Wigley hull and vertical/canted strut SWATHs were conducted. In the single and double integral parts of Green's function, the method of special function expansion and Chebyshev polynomial approach were adopted respectively. The formulas for zeroth-first-and second-order wave-making resistance were derived. In a towing tank, the calm water resistance experiment of SWATH model ASW-2 with canted strut was conducted and researched. The influences of waterline integral term, the surface mesh number, element node number, range of the integration and truncation of special function expansions on velocity potential and numerical results of resistance were investigated, and the difference between the zeroth-order and first-order wave resistance was analyzed. The theoretical calculation results agree well with the well-found model experimental results.展开更多
It is the result of a systemic study about uniform hematite nanopallets with length of about 100 nm, width of about 30 nm, and thickness of less than 10 nm. The sample has superparamagnetic(SPM) properties above the b...It is the result of a systemic study about uniform hematite nanopallets with length of about 100 nm, width of about 30 nm, and thickness of less than 10 nm. The sample has superparamagnetic(SPM) properties above the blocking temperature of ～16 K. The temperature dependence of magnetization was well fitted by Bloch T^(3/2) law considering the dipolar interaction of the particles. The field dependence of magnetization was fitted with revised Langevin equation.The magnetization of the weak ferromagnetic(WF) canted spins contributes to the linear portion in the high field region;the surface uncompensated spins and the parasitic ferromagnetic moments due to the canted spins both contribute to the particle moments and the superparamagnetic behavior.展开更多
基金Project supported by the Fundamental Development Fund and Chancellor Scholarship Program,China (Grant No.YJ2010-014)the Fundamental Research Funds for the Central Universities of China (Grant No. FRF-BR-09-007A)
文摘We have reported new magnetic and optical properties of Mn2O3 nanostructures. The nanostructures have been synthesized by the hydrothermal method combined with the adjustment of pH values in the reaction system. The particular characteristics of the nanostructures have been analyzed by employing X-Ray diffraction （XRD）, scanning electron microscopy （SEM）, energy dispersive X-ray （EDX） analysis, transmission electron microscopy （TEM）, high resolution transmission electron microscopy （HRTEM）, Raman spectroscopy （RS）, UV-visible spectroscopy, and the vibrating sample magnetometer （VSM）. Structural investigation manifests that the synthesized Mn2O3 nanostructures are orthorhombic crystal. Magnetic investigation indicates that the Mn2O3 nanostructures are antiferromagnetic and the antiferromagnetic transition temperature is at TN = 83 K. Furthermore, the Mn2O3 nanostructures possess canted antiferromagnetic order below the Neel temperature due to spin frustration, resulting in hysteresis with large coercivity （1580 Oe） and remnant magnetization （1.52 emu/g）. The UV-visible spectrophotometry was used to determine the transmittance behaviour of Mn203 nanostructures. A direct optical band gap of 1.2 eV was acquired by using the Davis-Mott model. The UV-visible spectrum indicates that the absorption is prominent in the visible region, and transparency is more than 80% in the UV region.
文摘A new three-dimensional nickel（Ⅱ） hydrogen-bonded molecular self assembly containing [（Ni（nicotinamide）2（thiocyanate）2（H2O）2] complex has been synthesized and characterized by single-crystal X-ray diffraction,FTIR spectroscopy,thermal analysis and magnetic measurements.Structural analysis reveals that the complex crystallizes in triclinic space group P1（crystal data a = 7.5574,b = 8.2683,c = 9.0056 A,α = 73.010,β = 69.698,γ = 66.51） and exhibits a distorted octahedral coordination sphere.Most interesting point in its structure is the involvement of sulphur atom of thiocyanate moiety in the trifurcated hydrogen bonding to build up the hydrogen-bonded self assembly.The magnetic behavior as determined by squid magnetometer（2~300 K temp.range） reveals dominating antiferromagnetic interaction followed by spin canting behavior below 20 K.
基金Project supported by the National Natural Science Foundation of China(Grant No.Y1JA011x11)
文摘High quality single crystal CaFe4As3 was grown by using the Sn flux method. Unlike layered CaFe2As2, CaFe4As3 crystallizes in an orthorhombic three-dimensional structure. Two magnetic ordering transitions are observed at - 90 K and - 27 K, respectively. The high temperature transition is an antiferromagnetic（AF） ordering transition. However, the low temperature transition shows complex properties. It shows a ferromagnetic-like transition when a field is applied along b-axis, while antiferromagnetism-like transition when a field is applied perpendicular to b-axis. These results suggest that the low temperature transition at 27 K is a first-order transition from an AF state to a canted AF state. In addition, the low temperature electron specific heat coefficient reaches as high as 143 mJ/mol.K2, showing a heavy fermion behavior.
文摘By using the derivative method, we obtained the same result with that of the previous work of Chen et al. in 2006. Different from the integral form, the derivative form of the surface expression published in this paper is derived from differential equation and based on the theory of non-imaging focusing heliostat proposed by Chen et al. in 2001. The comparison of the derivative form of fixed aberration correction surface has been made with that of integral form surface as well as that of spherical surface in concentrating the solar ray.
基金The project was supported by the National Natural Science Foundation of China(21461003)the Guangxi Natural Science Foundation of China(2016GXNSFFA380010 and 2016GXNSFAA380206)the Project of Guangxi Education Department(KY2016LX235)
文摘Based on the bent ligand 1 H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole(3,4?-Hbpt) with Co(Ⅱ) ions as well as a series of polycarboxylate co-ligands, three new coordination polymers were yielded, namely, {[Co(op)(3,4?-Hbpt)(H_2O)_3]?2 H_2O}n(1), [Co(cyc)(3,4′-Hbpt)(H_2O)]n(2) and [Co(pro)(3,4′-Hbpt)(H_2O)]n(3)(here, op = o-phthalic anion, cyc = 1,1-cyclobutanedicarboxylic anion, pro = propanedioic anion). In cooperation with the auxiliary polycarboxylate co-ligands, a variety of Co(Ⅱ) coordination networks, such as 1-D chain 1 and 2-D layer 2 and 3 have been assembled. The magnetic behaviors of compounds 1～3 were studied. All of them indicated the existence of interesting spin-canting behavior.
基金supported by the National Natural Science Foundation of China(Grant NO.12104407)the Natural Science Foundation of Zhejiang Province(Grant NO.LQ20A040004)
文摘The Heisenberg-Kitaev(HK)model on various lattices has attracted a lot of attention because it may lead to exotic states such as quantum spin liquid and topological orders.The rare-earth-based kagome lattice(KL)compounds Mg_(2)RE_(3)Sb_(3)O_(14)(RE=Gd,Er)and(RE=Nd)have q=0,120°order and canted ferromagnetic(CFM)order,respectively.Interestingly,the HK model on the KL has the same ground state long-range orders.In the theoretical phase diagram,the CFM phase resides in a continuous parameter region and there is no phase change across special parameter points,such as the Kitaev ferromagnetic(KFM)point,the ferromagnetic(FM)point and its dual FM point.However,a ground state property cannot distinguish a system with or without topological nontrivial excitations and related phase transitions.Here,we study the topological magnon excitations and related thermal Hall conductivity in the HK model on the KL with CFM order.The CFM phase can be divided into two regions related by the Klein duality,with the self dual KFM point as their boundary.We find that the scalar spin chirality,which is intrinsic in the CFM order,changes sign across the KFM point.This leads to the opposite Chem numbers of corresponding magnon bands in the two regions,and also the sign change of the magnon thermal Hall conductivity.
文摘Analyses of the new slender-ship theory of wave resistance were made and corresponding calculation methods were proposed. Based on these theoretical methods, the calculations of wave resistance of near surface submersible, Wigley hull and vertical/canted strut SWATHs were conducted. In the single and double integral parts of Green's function, the method of special function expansion and Chebyshev polynomial approach were adopted respectively. The formulas for zeroth-first-and second-order wave-making resistance were derived. In a towing tank, the calm water resistance experiment of SWATH model ASW-2 with canted strut was conducted and researched. The influences of waterline integral term, the surface mesh number, element node number, range of the integration and truncation of special function expansions on velocity potential and numerical results of resistance were investigated, and the difference between the zeroth-order and first-order wave resistance was analyzed. The theoretical calculation results agree well with the well-found model experimental results.
基金financially supported by the National Natural Science Foundation of China (Nos. 11674023, 51371015,51331002, and 51501004)Beijing Municipal Science and Technology Project (No. 217111000220000)
文摘It is the result of a systemic study about uniform hematite nanopallets with length of about 100 nm, width of about 30 nm, and thickness of less than 10 nm. The sample has superparamagnetic(SPM) properties above the blocking temperature of ～16 K. The temperature dependence of magnetization was well fitted by Bloch T^(3/2) law considering the dipolar interaction of the particles. The field dependence of magnetization was fitted with revised Langevin equation.The magnetization of the weak ferromagnetic(WF) canted spins contributes to the linear portion in the high field region;the surface uncompensated spins and the parasitic ferromagnetic moments due to the canted spins both contribute to the particle moments and the superparamagnetic behavior.
