Substituting effects of Nd for La in La 0.5 Ba 0.5 CoO 3 compounds were studied systematically. The results show that Nd doping does not change the itinerant properties of the Co3d electrons. The molecular ma...Substituting effects of Nd for La in La 0.5 Ba 0.5 CoO 3 compounds were studied systematically. The results show that Nd doping does not change the itinerant properties of the Co3d electrons. The molecular magnetic moment of the materials decreases monotonically with increasing Nd dopant. When Nd content x ≥0.45, a magnetic phase separation appears in the materials. When x ≤0.45, the Curie temperature decreases monotonically with increasing Nd dopant. This is due to the size effects of the rare earth ions. The electric resistance measurements show that in the studied temperature range, the conduction of the materials belongs to the thermo diffusion conduction below the Curie temperature, while it belongs to the variable range hopping conduction of polarons over the Curie temperature.展开更多
The compound ingots of Pr0.15TbxDy0.85-xFe2 (x=0 to 0.85) were prepared by arc melting in a water Cu boat using arc furnace under a purified Ar atmosphere. Appropriate annealing (850℃, 100 h) can obtain single Laves ...The compound ingots of Pr0.15TbxDy0.85-xFe2 (x=0 to 0.85) were prepared by arc melting in a water Cu boat using arc furnace under a purified Ar atmosphere. Appropriate annealing (850℃, 100 h) can obtain single Laves phase compound. The magnetostriction for these systems will rise obviously when partially substituted Tb or Dy by Pr.展开更多
NdCl 3 FeCl 3 graphite intercalation compounds were synthesized by molten salt exchange method. The state of the intercalates and the relative contents of Nd, Fe, Cl, C in the product were determined by X ray ph...NdCl 3 FeCl 3 graphite intercalation compounds were synthesized by molten salt exchange method. The state of the intercalates and the relative contents of Nd, Fe, Cl, C in the product were determined by X ray photoelectron spectroscopy(XPS). From the XPS data, it is concluded that the binding energy of Fe2p electrons is about 711 20～710 3 eV, the binding energy of Nd3d electrons is about 983 08～983 20 eV, and Fe in the product has two valence states (Fe 3+ and Fe 2+ ).展开更多
The alloy with nominal composition Sm_2(Fe0.94Ti0.06)17 is prepared by arc-melting, hydrogenation and nitrogenation processes. The Sm_2(Fe0.94Ti0.06)17 alloy has a single phase of Sm_3(Fe, Ti)29 with the Nd_3(Fe, Ti)...The alloy with nominal composition Sm_2(Fe0.94Ti0.06)17 is prepared by arc-melting, hydrogenation and nitrogenation processes. The Sm_2(Fe0.94Ti0.06)17 alloy has a single phase of Sm_3(Fe, Ti)29 with the Nd_3(Fe, Ti)29-type structure. The corresponding hydride phase with the same phase structure of the parent alloy was formed after a hydrogen decrepitation (HD) process at 300℃. The hydrogenation at 800℃ mainly shows a HDDR process. The HD and nitrogenation at 500℃ result in increasing the Curie temperature of the alloy by 72℃ and by 158℃ due to lattice expansions, respectively. The anisotropic and isotropic Sm_3(Fe. Ti)29N_y magnets are obtained after HD, HDDR and the consequent nitrogenation, respectively. The optimum magnetic properties of Sm_3(Fe, Ti)29N_y powders achieved in the above two processes are: (i) B_r=0;82 T, _iH_c=4.48 kA/cm. (BH)_max=54.3 kJ/m^3, (ii) B_r=0.68 T, _iH_c=8.14 kA/cm, (BH)max=66.4 kJ/m^3.展开更多
采用实心焊丝和气保护药芯焊丝分别全位置自动填充盖面焊φ1422 mm×38.5 mm X80钢管,通过焊接操作、焊缝成形、无损检测及对环焊接头的力学性能试验研究,确定了壁厚38.5 mm X80钢管的自动焊工艺。结果表明:未熔合是壁厚38.5 mm X8...采用实心焊丝和气保护药芯焊丝分别全位置自动填充盖面焊φ1422 mm×38.5 mm X80钢管,通过焊接操作、焊缝成形、无损检测及对环焊接头的力学性能试验研究,确定了壁厚38.5 mm X80钢管的自动焊工艺。结果表明:未熔合是壁厚38.5 mm X80钢管自动焊的主要缺陷类型,通过控制坡口尺寸,并选择合适的焊接工艺参数能获取合格的环焊接头;采用实心焊丝或气保护药芯焊丝自动填充、盖面焊壁厚38.5 mm X80环焊接头均能够满足目前长输管道工程标准中的相关规范要求。展开更多
The crystal structure, magnetic and magnetocaloric properties of(Ho_(1-x) Y_(0.5))_5 Pd_2 compounds are investigated. All the compounds crystallize in a cubic Dy_5 Pd_2-type structure with the space group Fd3 m and un...The crystal structure, magnetic and magnetocaloric properties of(Ho_(1-x) Y_(0.5))_5 Pd_2 compounds are investigated. All the compounds crystallize in a cubic Dy_5 Pd_2-type structure with the space group Fd3 m and undergo a second order transition from spin glass(SG) state to paramagnetic(PM) state. The spin glass transition temperatures T_g decrease from 26 K for x = 0 to 13 K for x = 0.5. In the PM region, the reciprocal susceptibilities for all the compounds obey the Curie–Weiss law. The paramagnetic Curie temperatures(θp) for Ho_5 Pd_2,(Ho_(0.75) Y_(0.25)_5 Pd_2, and(Ho_(0.5) Y_(0.5))_5 Pd_2 are determined to be 32 K, 30 K, and 22 K, respectively, and the corresponding effective magnetic moments(μeff) are10.8 μB/Ho, 10.3 μB/RE, and 7.5 μB/RE, respectively. Magnetocaloric effect(MCE) is anticipated according to the Maxwell relation, based on the isothermal magnetization curves. For a magnetic field change of 0–5 T, the maximum values of the isothermal magnetic entropy change-?SMof the(Ho_(1-x)Y_x)_5 Pd_2(x = 0, 0.25, and 0.5) compounds are determined to be 11.5 J·kg^(-1)·K^(-1), 11.1 J·kg^(-1)·K^(-1), and 8.9 K J·kg^(-1)·K^(-1), with corresponding refrigerant capacity values of 382.3 J·kg^(-1), 336.2 J·kg^(-1), and 242.5 J·kg^(-1), respectively.展开更多
The effects of different annealing conditions on the phase formation with NaZn13 structure were investigated in La（Fe1-xCox）11.9Si1.1 （x=0.068） compounds. It was found that the 1：13 phase was not formed directly ...The effects of different annealing conditions on the phase formation with NaZn13 structure were investigated in La（Fe1-xCox）11.9Si1.1 （x=0.068） compounds. It was found that the 1：13 phase was not formed directly from the melt upon cooling but via a peritectic reaction between the pro-peritectic γ-Fe and the La-rich phase. Annealing temperature was very important for the formation of 1：13 phase. Ice water was confirmed to be a preferable quenching medium. La（Fe1-xCox）11.9Si1.1 （x=0.068） compounds with almost single 1：13 phase were obtained at 1473 K after 15 d.展开更多
The distribution of trivalent and tetravalent cations in several ATxV6-xO11 compounds was quantitatively studied by the bond valence method. In SrV6O11, the M(3) sites were mainly occupied by trivaient cations; while ...The distribution of trivalent and tetravalent cations in several ATxV6-xO11 compounds was quantitatively studied by the bond valence method. In SrV6O11, the M(3) sites were mainly occupied by trivaient cations; while M(1) and M(2) sites were shared by trivalent and tetravalent cations, the relative content of tetravalent at M(1) sites was higher than at M(2) sites. During substitution process, the trivalent cations preferred to occupy M(3) sites, tetravalent ones preferred to occupy M(2) sites. The occupancy of trivalent and tetravalent cations at M sites would change with the substitution展开更多
A systematic study of syntheses and magnetic properties of the Nd_3Fe_(29-x)Cr_x (x=4.5, 4.7, 5.0, and 5.5) compounds has been performed. The single-phase compounds of Nd_3Fe_(29-x)Cr_x can be formed in the range 4.5...A systematic study of syntheses and magnetic properties of the Nd_3Fe_(29-x)Cr_x (x=4.5, 4.7, 5.0, and 5.5) compounds has been performed. The single-phase compounds of Nd_3Fe_(29-x)Cr_x can be formed in the range 4.5≤ x ≤ 5.5. The Curie temperature T_C, the saturation magnetization M_s at 4.2 K, the anisotropy field H_A at 4.2 K and room temperature. and the intra-sublattice exchange coupling parameter j_(FeFe) at 4.2 K for the Nd_3Fe_(29-x)Cr_x compounds decrease with increasing Cr composition from x=4.5 to 5.5, respectively. Nitrogenation and carbonation, unlike hydrogenation. result mainly in improvements of the Curie temperature, the saturation magnetization and the anisotropy field at 4.2 K and room temperature for the Nd_3Fe_(29-x)Cr_x compounds compared with their parent compounds.展开更多
The melting behavior,solid state phase transformation and structure of pseudo-ternary compounds Nd_2(Fe_(1-x)Ni_x)_(14)B and Pr_2(Co_(1-y)Ni_y)_(14)B were studied using differential thermal analysis,optical microscopy...The melting behavior,solid state phase transformation and structure of pseudo-ternary compounds Nd_2(Fe_(1-x)Ni_x)_(14)B and Pr_2(Co_(1-y)Ni_y)_(14)B were studied using differential thermal analysis,optical microscopy X-ray diffraction,and electron probe micro-analysis techniques.At high temperature,eutectoid decomposition R_2(Ni,M)_(17)→R(Ni,M)_5+x-Ni(M) takes place in these two pseudo-ternary compounds,in the composition range x=0.6～1.0 and y=0.3～1.0,respectively.When x(or y)≤0.2,both Nd_2(Fe_(1-x)Ni_x)_(14)B and Pr_2(Co_(1-y)Ni_y)_(14)B are single phase tetragonal.The phase constitutents of these two systems at room tempera- ture are similar in the composition range 0.6≤x(or y)≤1.0.展开更多
The crystallographic structure and intrinsic magnetic properties have been investigated in the RTiFe_(11), RTiCo_(11) and RTi(Fe_(1-X)Ni_X)_(11) compounds,where R represents Nd,Sm,Gd,Tb,Dy,Ho,Er and Y.Neutron diffract...The crystallographic structure and intrinsic magnetic properties have been investigated in the RTiFe_(11), RTiCo_(11) and RTi(Fe_(1-X)Ni_X)_(11) compounds,where R represents Nd,Sm,Gd,Tb,Dy,Ho,Er and Y.Neutron diffraction and Mossbauer spectra analyses have been used to study the nuclear and magnetic structure of these compounds.the Fe,Co,Ni and Ti atoms are found to exhibit strong site preference with f and j sites fa- voring Fe,Co and Ni atoms and the i site Ti atoms.Two different types of magnetic behavior were observed in the RTiFe_(11) and RTiCo_(11) compounds.In the former,the interatomic distance and the number of nearest neighbor atoms play essential roles.In particular,anomalous thermal expansion behavior is presented in RTiFe_(11).In the latter,the magnetic properties are essentially determined by the modification of the cobalt electronic configuration brought about by the transfer of rare earth conduction electrons to the transition 3d band.The saturation magnetization,Curie temperature and magnetocrystalline anisotropy data of RTiFe_(11), RTiCo_(11)and YTi(Fe_(1-X)Ni_X)_(11)are presented.A tempt to improve the intrinsic magnetic properties in RTiFe_(11)has been made,and the results are reported.On the basis of the crystalline field theory by using a single-ion model,the anisotropy constants and their temperature dependence of the R ions have been calcu- lated,which helps explain the spin reorientation observed in RTiFe_(11).展开更多
The structural, elastic and electronic properties of Cu-X compounds in the Cu-X(X =Al, Be, Mg, Sn, Zn and Zr) systems were predicted systematically by first-principles calculations. The ground state properties such as...The structural, elastic and electronic properties of Cu-X compounds in the Cu-X(X =Al, Be, Mg, Sn, Zn and Zr) systems were predicted systematically by first-principles calculations. The ground state properties such as lattice constant, bulk modulus(B)and it's pressure derivative(B') were predicted by fitting a four-parameter Birch–Murnaghan equation and the elastic constants(cij′s)are determined by an efficient strain-stress method. The calculated lattice parameters and cij′s of these binary compounds agree well with the available experimental data in the literature. In addition, elastic properties of polycrystalline aggregates including bulk modulus(B), shear modulus(G), elastic modulus(E), B/G(bulk/shear) ratio, and anisotropy ratio(AU) are calculated and compared with the experimental and theoretical results available in the literature. Based on electronic density of states(DOS) analysis, it can be revealed that all the compounds in the present work are metallic in nature.展开更多
The x-ray compound lens is a novel refractive x-ray optical device. This paper reports the authors＇ recent research on a polymethyl methacrylate （PMMA） compound x-ray lens. Firstly the designing and LIGA fabricatio...The x-ray compound lens is a novel refractive x-ray optical device. This paper reports the authors＇ recent research on a polymethyl methacrylate （PMMA） compound x-ray lens. Firstly the designing and LIGA fabrication process for the PMMA compound x-ray lens are briefly described. Then, a method for theoretical analysis, as well as the experimental system for measurement is also introduced. Finally, the focusing spots for 8keV monochromatic x-rays by the PMMA compound x-ray lens are measured and analysed. According to the experimental results, it is concluded that the PMMA compound x-ray lens promises a good focusing performance under the high-energy x-rays.展开更多
New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure ...New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure of Sr0.6Bi0.4FeO2.7has been determined by X-ray single crystal diffraction,and the data of neutron powder diffraction collected at both room temperature and elevated temperature(380℃).The compound Sr0.6Bi0.4FeO2.7 crystallizes in the cubic space group of Pm3m with Z=1,a=3.9330(6) at room temperature,a=3.9498(6)A at 380℃.The magnetic structure from the neutron powder diffraction data collected at room temperature is consistent with a simple G-type antiferromagnetism and has a magnetic moment of 4.98 μB per Fe atom.The structures of Sr1-xBixFeO3-y with x other than 0.4 were also refined from the X-ray powder diffraction data.The data were consistent with a tetragonal cell when x=0.1,a rhombohedral cell when x= 0.9,and a cubic cell for x=0.2～0.8.From single crystal X-ray diffraction data,Ba1.5Pt0.5Mn2O6 crystallizes in hexagonal space group of P63mc with a= 5.7722 (6),c=4.4504(9),V=128.42(2),Z=1.The Sr(1-x)BixFeO(3-y)are found to be a good electronic and ionic conductor.展开更多
文摘Substituting effects of Nd for La in La 0.5 Ba 0.5 CoO 3 compounds were studied systematically. The results show that Nd doping does not change the itinerant properties of the Co3d electrons. The molecular magnetic moment of the materials decreases monotonically with increasing Nd dopant. When Nd content x ≥0.45, a magnetic phase separation appears in the materials. When x ≤0.45, the Curie temperature decreases monotonically with increasing Nd dopant. This is due to the size effects of the rare earth ions. The electric resistance measurements show that in the studied temperature range, the conduction of the materials belongs to the thermo diffusion conduction below the Curie temperature, while it belongs to the variable range hopping conduction of polarons over the Curie temperature.
基金the Natural Science Foundation of Hebei Province 596028 and the National NaturalScience Foundation of China No.59871062.
文摘The compound ingots of Pr0.15TbxDy0.85-xFe2 (x=0 to 0.85) were prepared by arc melting in a water Cu boat using arc furnace under a purified Ar atmosphere. Appropriate annealing (850℃, 100 h) can obtain single Laves phase compound. The magnetostriction for these systems will rise obviously when partially substituted Tb or Dy by Pr.
文摘NdCl 3 FeCl 3 graphite intercalation compounds were synthesized by molten salt exchange method. The state of the intercalates and the relative contents of Nd, Fe, Cl, C in the product were determined by X ray photoelectron spectroscopy(XPS). From the XPS data, it is concluded that the binding energy of Fe2p electrons is about 711 20～710 3 eV, the binding energy of Nd3d electrons is about 983 08～983 20 eV, and Fe in the product has two valence states (Fe 3+ and Fe 2+ ).
基金National Natural Science FOundation of China!59571014National Natural Science FOundation of China!59725103National Natur
文摘The alloy with nominal composition Sm_2(Fe0.94Ti0.06)17 is prepared by arc-melting, hydrogenation and nitrogenation processes. The Sm_2(Fe0.94Ti0.06)17 alloy has a single phase of Sm_3(Fe, Ti)29 with the Nd_3(Fe, Ti)29-type structure. The corresponding hydride phase with the same phase structure of the parent alloy was formed after a hydrogen decrepitation (HD) process at 300℃. The hydrogenation at 800℃ mainly shows a HDDR process. The HD and nitrogenation at 500℃ result in increasing the Curie temperature of the alloy by 72℃ and by 158℃ due to lattice expansions, respectively. The anisotropic and isotropic Sm_3(Fe. Ti)29N_y magnets are obtained after HD, HDDR and the consequent nitrogenation, respectively. The optimum magnetic properties of Sm_3(Fe, Ti)29N_y powders achieved in the above two processes are: (i) B_r=0;82 T, _iH_c=4.48 kA/cm. (BH)_max=54.3 kJ/m^3, (ii) B_r=0.68 T, _iH_c=8.14 kA/cm, (BH)max=66.4 kJ/m^3.
文摘采用实心焊丝和气保护药芯焊丝分别全位置自动填充盖面焊φ1422 mm×38.5 mm X80钢管,通过焊接操作、焊缝成形、无损检测及对环焊接头的力学性能试验研究,确定了壁厚38.5 mm X80钢管的自动焊工艺。结果表明:未熔合是壁厚38.5 mm X80钢管自动焊的主要缺陷类型,通过控制坡口尺寸,并选择合适的焊接工艺参数能获取合格的环焊接头;采用实心焊丝或气保护药芯焊丝自动填充、盖面焊壁厚38.5 mm X80环焊接头均能够满足目前长输管道工程标准中的相关规范要求。
基金Project supported by the National Basic Research Program of China(Grant No.2014CB643703)the National Key Research and Development Program of China(Grant No.2016YFB0700901)+1 种基金the National Natural Science Foundation of China(Grant Nos.51261004 and 51761007)Guangxi Natural Science Foundation,China(Grant No.2018GXNSFAA294051)
文摘The crystal structure, magnetic and magnetocaloric properties of(Ho_(1-x) Y_(0.5))_5 Pd_2 compounds are investigated. All the compounds crystallize in a cubic Dy_5 Pd_2-type structure with the space group Fd3 m and undergo a second order transition from spin glass(SG) state to paramagnetic(PM) state. The spin glass transition temperatures T_g decrease from 26 K for x = 0 to 13 K for x = 0.5. In the PM region, the reciprocal susceptibilities for all the compounds obey the Curie–Weiss law. The paramagnetic Curie temperatures(θp) for Ho_5 Pd_2,(Ho_(0.75) Y_(0.25)_5 Pd_2, and(Ho_(0.5) Y_(0.5))_5 Pd_2 are determined to be 32 K, 30 K, and 22 K, respectively, and the corresponding effective magnetic moments(μeff) are10.8 μB/Ho, 10.3 μB/RE, and 7.5 μB/RE, respectively. Magnetocaloric effect(MCE) is anticipated according to the Maxwell relation, based on the isothermal magnetization curves. For a magnetic field change of 0–5 T, the maximum values of the isothermal magnetic entropy change-?SMof the(Ho_(1-x)Y_x)_5 Pd_2(x = 0, 0.25, and 0.5) compounds are determined to be 11.5 J·kg^(-1)·K^(-1), 11.1 J·kg^(-1)·K^(-1), and 8.9 K J·kg^(-1)·K^(-1), with corresponding refrigerant capacity values of 382.3 J·kg^(-1), 336.2 J·kg^(-1), and 242.5 J·kg^(-1), respectively.
基金the National Natural Science Foundation of China (50571008)the National Basic Research Program of China (2006CB601100)
文摘The effects of different annealing conditions on the phase formation with NaZn13 structure were investigated in La（Fe1-xCox）11.9Si1.1 （x=0.068） compounds. It was found that the 1：13 phase was not formed directly from the melt upon cooling but via a peritectic reaction between the pro-peritectic γ-Fe and the La-rich phase. Annealing temperature was very important for the formation of 1：13 phase. Ice water was confirmed to be a preferable quenching medium. La（Fe1-xCox）11.9Si1.1 （x=0.068） compounds with almost single 1：13 phase were obtained at 1473 K after 15 d.
文摘The distribution of trivalent and tetravalent cations in several ATxV6-xO11 compounds was quantitatively studied by the bond valence method. In SrV6O11, the M(3) sites were mainly occupied by trivaient cations; while M(1) and M(2) sites were shared by trivalent and tetravalent cations, the relative content of tetravalent at M(1) sites was higher than at M(2) sites. During substitution process, the trivalent cations preferred to occupy M(3) sites, tetravalent ones preferred to occupy M(2) sites. The occupancy of trivalent and tetravalent cations at M sites would change with the substitution
文摘A systematic study of syntheses and magnetic properties of the Nd_3Fe_(29-x)Cr_x (x=4.5, 4.7, 5.0, and 5.5) compounds has been performed. The single-phase compounds of Nd_3Fe_(29-x)Cr_x can be formed in the range 4.5≤ x ≤ 5.5. The Curie temperature T_C, the saturation magnetization M_s at 4.2 K, the anisotropy field H_A at 4.2 K and room temperature. and the intra-sublattice exchange coupling parameter j_(FeFe) at 4.2 K for the Nd_3Fe_(29-x)Cr_x compounds decrease with increasing Cr composition from x=4.5 to 5.5, respectively. Nitrogenation and carbonation, unlike hydrogenation. result mainly in improvements of the Curie temperature, the saturation magnetization and the anisotropy field at 4.2 K and room temperature for the Nd_3Fe_(29-x)Cr_x compounds compared with their parent compounds.
基金the National Natural Science Fundation of China.
文摘The melting behavior,solid state phase transformation and structure of pseudo-ternary compounds Nd_2(Fe_(1-x)Ni_x)_(14)B and Pr_2(Co_(1-y)Ni_y)_(14)B were studied using differential thermal analysis,optical microscopy X-ray diffraction,and electron probe micro-analysis techniques.At high temperature,eutectoid decomposition R_2(Ni,M)_(17)→R(Ni,M)_5+x-Ni(M) takes place in these two pseudo-ternary compounds,in the composition range x=0.6～1.0 and y=0.3～1.0,respectively.When x(or y)≤0.2,both Nd_2(Fe_(1-x)Ni_x)_(14)B and Pr_2(Co_(1-y)Ni_y)_(14)B are single phase tetragonal.The phase constitutents of these two systems at room tempera- ture are similar in the composition range 0.6≤x(or y)≤1.0.
文摘The crystallographic structure and intrinsic magnetic properties have been investigated in the RTiFe_(11), RTiCo_(11) and RTi(Fe_(1-X)Ni_X)_(11) compounds,where R represents Nd,Sm,Gd,Tb,Dy,Ho,Er and Y.Neutron diffraction and Mossbauer spectra analyses have been used to study the nuclear and magnetic structure of these compounds.the Fe,Co,Ni and Ti atoms are found to exhibit strong site preference with f and j sites fa- voring Fe,Co and Ni atoms and the i site Ti atoms.Two different types of magnetic behavior were observed in the RTiFe_(11) and RTiCo_(11) compounds.In the former,the interatomic distance and the number of nearest neighbor atoms play essential roles.In particular,anomalous thermal expansion behavior is presented in RTiFe_(11).In the latter,the magnetic properties are essentially determined by the modification of the cobalt electronic configuration brought about by the transfer of rare earth conduction electrons to the transition 3d band.The saturation magnetization,Curie temperature and magnetocrystalline anisotropy data of RTiFe_(11), RTiCo_(11)and YTi(Fe_(1-X)Ni_X)_(11)are presented.A tempt to improve the intrinsic magnetic properties in RTiFe_(11)has been made,and the results are reported.On the basis of the crystalline field theory by using a single-ion model,the anisotropy constants and their temperature dependence of the R ions have been calcu- lated,which helps explain the spin reorientation observed in RTiFe_(11).
基金Project(51021063)supported by Creative Research Group of National Natural Science Foundation of ChinaProject(2011CB610401)supported by National Basic Research Program of ChinaProject(2014M552150)supported by Postdoctoral Science Foundation of China
文摘The structural, elastic and electronic properties of Cu-X compounds in the Cu-X(X =Al, Be, Mg, Sn, Zn and Zr) systems were predicted systematically by first-principles calculations. The ground state properties such as lattice constant, bulk modulus(B)and it's pressure derivative(B') were predicted by fitting a four-parameter Birch–Murnaghan equation and the elastic constants(cij′s)are determined by an efficient strain-stress method. The calculated lattice parameters and cij′s of these binary compounds agree well with the available experimental data in the literature. In addition, elastic properties of polycrystalline aggregates including bulk modulus(B), shear modulus(G), elastic modulus(E), B/G(bulk/shear) ratio, and anisotropy ratio(AU) are calculated and compared with the experimental and theoretical results available in the literature. Based on electronic density of states(DOS) analysis, it can be revealed that all the compounds in the present work are metallic in nature.
基金Project supported by the National Natural Science Foundation of China （Grant No 10174079）, the Natural Science Foundation of Zhejiang Province, China （Grant No Y104203） and BEPC National Laboratory （Grant No sr-03062）.
文摘The x-ray compound lens is a novel refractive x-ray optical device. This paper reports the authors＇ recent research on a polymethyl methacrylate （PMMA） compound x-ray lens. Firstly the designing and LIGA fabrication process for the PMMA compound x-ray lens are briefly described. Then, a method for theoretical analysis, as well as the experimental system for measurement is also introduced. Finally, the focusing spots for 8keV monochromatic x-rays by the PMMA compound x-ray lens are measured and analysed. According to the experimental results, it is concluded that the PMMA compound x-ray lens promises a good focusing performance under the high-energy x-rays.
文摘New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure of Sr0.6Bi0.4FeO2.7has been determined by X-ray single crystal diffraction,and the data of neutron powder diffraction collected at both room temperature and elevated temperature(380℃).The compound Sr0.6Bi0.4FeO2.7 crystallizes in the cubic space group of Pm3m with Z=1,a=3.9330(6) at room temperature,a=3.9498(6)A at 380℃.The magnetic structure from the neutron powder diffraction data collected at room temperature is consistent with a simple G-type antiferromagnetism and has a magnetic moment of 4.98 μB per Fe atom.The structures of Sr1-xBixFeO3-y with x other than 0.4 were also refined from the X-ray powder diffraction data.The data were consistent with a tetragonal cell when x=0.1,a rhombohedral cell when x= 0.9,and a cubic cell for x=0.2～0.8.From single crystal X-ray diffraction data,Ba1.5Pt0.5Mn2O6 crystallizes in hexagonal space group of P63mc with a= 5.7722 (6),c=4.4504(9),V=128.42(2),Z=1.The Sr(1-x)BixFeO(3-y)are found to be a good electronic and ionic conductor.
