There were four doublets in the Mssbauer spectrum of cucumber (Cucumis sativus L.) photosystemⅡ (PSⅡ) particles. According to the value of isomer shift and quadrupole splitting, they represented oxidized cytochrome ...There were four doublets in the Mssbauer spectrum of cucumber (Cucumis sativus L.) photosystemⅡ (PSⅡ) particles. According to the value of isomer shift and quadrupole splitting, they represented oxidized cytochrome b559 (Cyt_b559), reduced Cyt_b559, Fe 3+ _quinone (Q) complex, and Fe 2+ _Q complex respectively. After water_stress, the electron transport rate between Q A (primary quinone electron acceptor of PSⅡ)/Q B(secondary quinone electron acceptor of PSⅡ) was affected and the absorption doublets of Fe 2+ disappeared, suggesting that the reduced Cyt_b559 and Fe 2+ _Q complex had been oxidized. The results indicated that water_stress had changed the redox status of iron in the iron_quinone complex. Iron took part in electron transport through the change from a state of reduction to oxidation.展开更多
Mssbauer spectrum and three dimensional atom probes（3DAP） were combined to investigate the mechanism of cementite dissolution in a cold-drawn eutectoid steel at a true strain of 2.89.The experimental results suggest...Mssbauer spectrum and three dimensional atom probes（3DAP） were combined to investigate the mechanism of cementite dissolution in a cold-drawn eutectoid steel at a true strain of 2.89.The experimental results suggest that the dislocations play an important role in the dissolution of the cementite by sweeping across the nano-scaled cementite,and transferring carbon from cementite to ferrite inducing cementite decomposition.The mechanism of cementite dissolution in the steel is discussed in association with the investigation of nonstoichiometric cementite structure after heavy deformation.展开更多
The M?ssbauer spectra of natural megacrystal clinopyroxene are usually fitted by 4 sets of symmetric doublets, A-A', B-B', C-C' and D-D', respectively, in terms of increasing Qs value in literature. Bu...The M?ssbauer spectra of natural megacrystal clinopyroxene are usually fitted by 4 sets of symmetric doublets, A-A', B-B', C-C' and D-D', respectively, in terms of increasing Qs value in literature. But the assignments of those doublets are quite different, except the D-D' doublet assigned to Fe3+at the lattice site M***1 in previous papers. Particularly, the assignment and interpretation of the C-C' doublet are diverse.展开更多
Using 57 Fe Mssbauer effect, the chemical states of iron components were investigated for the barks of Platycladus orientalis, Cedrus deodara and Platanus acerifolia sampled from Lanzhou City, Ch...Using 57 Fe Mssbauer effect, the chemical states of iron components were investigated for the barks of Platycladus orientalis, Cedrus deodara and Platanus acerifolia sampled from Lanzhou City, China. All bark samples showed two overlapping doublets with large and small quadruple splitting. Only Platycladus orientalis's barks exhibited one sextet. Based on Mssbauer parameters, they were attributed to paramagnetic ferrous, paramagnetic ferric and magnetic iron, respectively. For the sampling site which is about 6 kilometers from Lanzhou Steel Factory, the ratio of ferrous to ferric was higher in the sample of Platanus acerifolia's barks, whereas the barks of Platycladus orientalis and Cedrus deodara gave similar values of this ratio. Platycladus orientalis was the most effective in accumulating iron complexes in barks among the three trees. Platanus acerifolia's barks sampled at Lanzhou Steel Factory's area exhibited higher absolute intensities of iron components and lower ration of ferrous to ferric, indicating that industrial air pollution is a contributing factor in accumulating iron compounds in the tree barks of this region.展开更多
Chemical bond properties of YBa 2Cu 3O 7 were studied by using the average ba nd-gap model. The calculated results show that the covalency of Cu(1)-O bond i s 0.406, and one of Cu(2)-O is 0.276. Mssbauer isomer shi...Chemical bond properties of YBa 2Cu 3O 7 were studied by using the average ba nd-gap model. The calculated results show that the covalency of Cu(1)-O bond i s 0.406, and one of Cu(2)-O is 0.276. Mssbauer isomer shifts of 57Fe in Y-123 were calculated by the chemical surrounding factor h v defined b y covalency and electronic polarizability. The charge-state and site of Fe were determined. The relation between the coupling constant of electron-phonon inte raction and covalency is employed to explain that the Cu(2)-O plane is more im portant than the Cu(1)-O chain on the superconductivity in the Y-123 compound s.展开更多
The martensite microstructure,amount of retained austenite and its carbon concentration in the 40CrNiMo steel quenched at various conditions have been investigated by using trans- mission Mossbauer spectroscopy at roo...The martensite microstructure,amount of retained austenite and its carbon concentration in the 40CrNiMo steel quenched at various conditions have been investigated by using trans- mission Mossbauer spectroscopy at room temperature.It was shown that high-temperature quenching and thermomechanical quenching has little influence on amount of retained austenite,thus the toughening effect of quenching was attributed to bulk lath martensite and its refining.展开更多
By using the chemical bond theory of dielectric description, the chemical bond parameters of (Tl, Pb) - 1223 was calculated. The results show that the Sr-O, Tl-O, and Ca-O types of bond have higher ionic character an...By using the chemical bond theory of dielectric description, the chemical bond parameters of (Tl, Pb) - 1223 was calculated. The results show that the Sr-O, Tl-O, and Ca-O types of bond have higher ionic character and the Cu-O types of bond have more covalent character. Mssbauer isomer shifts of 57Fe and 119Sn doped in (Tl, Pb) -1223 were calculated by using the chemical environmental factor, he, defined by covalency and electronic polarizability. Four valence state tin and three valence iron sites were identified in 57Fe, and 119Sn doped (Tl, Pb) -1223 superconductor. We conclude that all of the Fe atoms substitute the Cu at square planar Cu (1) site, whereas Sn prefers to substitute the square pyramidal Cu (2) site.展开更多
The effect of non-magnetic Al^3＋ ion doping on the magnetic properties of MnFe2-2x Al2xO4 （0 ≤x≤ 0.4） spinel ferrites was studied using Moessbauer spectroscopy measurements at room temperature. From the Moessbaue...The effect of non-magnetic Al^3＋ ion doping on the magnetic properties of MnFe2-2x Al2xO4 （0 ≤x≤ 0.4） spinel ferrites was studied using Moessbauer spectroscopy measurements at room temperature. From the Moessbauer study, it is observed that the ：esolved hyperfine sextets are due to the distribution of Fe ions on the two sublattices of the spinel ferrites. The value of the isomer shift obtained from the fitting of the Moessbauer spectra indicates that Fe ions are in ＋3 state. A paramagnetic doublet is observed at ：iegree of inversion x=0.4, superimposed on the hyperfine sextets, indicating that the super-exchange interaction A-B decreases due to ：he dilution of sublattice by Al^3＋ ions. The hyperfine magnetic field decreases at both interstitial sites of tetrahedral （A） and 3ctahedral （B） with the increase in Al concentration.展开更多
If recoilless fraction fa is available, the optimum absorber thickness dopt can be calculated by maximizing the signal to noise ratio or Q factor. In this work,an approach presented is to get experimental Qexp as a fu...If recoilless fraction fa is available, the optimum absorber thickness dopt can be calculated by maximizing the signal to noise ratio or Q factor. In this work,an approach presented is to get experimental Qexp as a function of the thickness,andthen fitting Qexp by its theoretical expression gives fa value. At last the dopt value is deduced from a maximum on the fitted curve.In such a way, thicknesses of six specimens with quadrupole or magnetic hyperfinc splitting were optimized.展开更多
The effects of Al substitution for Fe on the structure, magnetics, magnetostriction, anisotropy and spin reorientation of a series of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys (x=0.05, 0.1, 0.15, 0.2, 0.25, 0.3) at room te...The effects of Al substitution for Fe on the structure, magnetics, magnetostriction, anisotropy and spin reorientation of a series of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys (x=0.05, 0.1, 0.15, 0.2, 0.25, 0.3) at room temperature have been investigated. The alloys of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 substantially retain MgCu2-type C-15 cubic Laves phase structure when x【0.2. The mixed phases appear with x = 0.2, and cubic Laves phase decreases with increasing x. The magnetostriction of the Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys decreases drastically with increasing x and the giant magnetostrictive effect disappears for x 】 0.15. Fortunately, a small amount of Al substitution is beneficial to a decrease in the magnetocrystalline anisotropy. The spin reorientation temperature decreases with increasing x. The analysis of the Mssbauer spectra indicates that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the increase of Al concentration x, namely, spin reorientation, resulting in the change of macroscopical magnetic properties and magnetostriction. The hyperfine field decreases, but the isomer shifts increases with Al concentration increasing and the quadruple splitting QS shows a weak concentration dependence.展开更多
A few valuable results have been obtained by making use of the M(?)ssbauer effect in the study of ancient wares. However, rarely is this technique applied to study ancient porcelain. Ru kiln is one of the five famous ...A few valuable results have been obtained by making use of the M(?)ssbauer effect in the study of ancient wares. However, rarely is this technique applied to study ancient porcelain. Ru kiln is one of the five famous kilns (Ru, Jun, Guan, Ge and Ding kilns) made in Chinese Song Dynasty (A. D. 960—1279 ). It has high artistic value but there are only展开更多
Grandidierite MgAl<sub>3</sub>BSiO<sub>9</sub> is a rare island silicate with extra anion [BO<sub>3</sub>]. It was firstly found in granities in the south Madagascar and associated ...Grandidierite MgAl<sub>3</sub>BSiO<sub>9</sub> is a rare island silicate with extra anion [BO<sub>3</sub>]. It was firstly found in granities in the south Madagascar and associated with orthoclase, microcline, almandine, hercynite and tourmaline etc. Then it was reportedly found in Hungary （1918）. The mineral firstly found in China was produced in gneiss of M ashan Group, the Sandaogou area of Jixi City of Heilongjiang Province. The long pale bluish green column of the metamorphic mineral was 0.8—4.0 mm in length and associated with bytownite,展开更多
Since J. Reilly et al. reported their research achievements on FeTi and its hydrides for the first time in 1974, extensive attention and wide interest of relevant research groups have been stimulated. The various phas...Since J. Reilly et al. reported their research achievements on FeTi and its hydrides for the first time in 1974, extensive attention and wide interest of relevant research groups have been stimulated. The various phase compositions and their formation mechanism on FeTiH<sub>x</sub> materials have not been understood completely until now. p. Raj’s work is worth putting forward. He considered that the Fe-H bonding interaction played an important role in the transformation of FeTiH<sub>x</sub> from the β<sub>2</sub> to the γ-phase.展开更多
I. INTRODUCTIONIon-implantation technique is a new technique developed in recent years. It was first applied to semiconductor devices in the 1960s, and then widespread into many fields such as solid state physics and ...I. INTRODUCTIONIon-implantation technique is a new technique developed in recent years. It was first applied to semiconductor devices in the 1960s, and then widespread into many fields such as solid state physics and material science. However, only a展开更多
Since the theory of spinodal decomposition in a supersaturated solid solution was formulated by Hillert and Chan, the phenomena of spinodal decomposition have been found in many alloys. We found a modulated structure ...Since the theory of spinodal decomposition in a supersaturated solid solution was formulated by Hillert and Chan, the phenomena of spinodal decomposition have been found in many alloys. We found a modulated structure in 10Ni maraging steel. Some investigators suggested that the formation of a modulated structure does not always imply the spinodal decomposition, and the modulated structure could also result from nucleation and growth.展开更多
Ⅰ. INTRODUCTION Since the discovery of recoil-less resonance and absorption of low γ-rays-M(?)ssbauer effect, the meteorites were first investigated using the M(?)ssbauer spectra by Sprenkel-Segtl et al. in 1964.
1 Introduction That molecular properties depend on its structure is one of the central ideas of chemistry. As a first order approximation, topological structure, that is. the atomic constitution and its linkage in a m...1 Introduction That molecular properties depend on its structure is one of the central ideas of chemistry. As a first order approximation, topological structure, that is. the atomic constitution and its linkage in a molecule, may be taken into account. It has been known for a long time to the chemists, that more quantitative expressions of them, which are now so-called molecular topological indices, however, were not fully developed until recently.展开更多
^(57)Fe Mssbauer spectroscopy was used to study the mechanism and regularity of coal desulfurization by microwave irradiation combined with magnetic-separation and with chemical acid-leaching. The results of phase ana...^(57)Fe Mssbauer spectroscopy was used to study the mechanism and regularity of coal desulfurization by microwave irradiation combined with magnetic-separation and with chemical acid-leaching. The results of phase analyses show that the decomposing reaction of pyrite intrinsic in coal, caused by the selective dielectric heating of microwave electromagnetic energy, FeS_2→Fe_(1-x)S→FeS, consecutively progresses towards the right-hand side with increased irradiation time. The whole process of microwave desulfurization of raw coal consists of the initiation, the promotion, and the saturation stages. The optimum desulfurization efficiency for microwave irradiation combined with magnetic-separation treatment and with chemical acid-leaching treatment can be attained by appropriately controlling the irradiation time to enable the corresponding microwave treatment to lie in the promotion stage and the saturation stage, respectively.展开更多
文摘There were four doublets in the Mssbauer spectrum of cucumber (Cucumis sativus L.) photosystemⅡ (PSⅡ) particles. According to the value of isomer shift and quadrupole splitting, they represented oxidized cytochrome b559 (Cyt_b559), reduced Cyt_b559, Fe 3+ _quinone (Q) complex, and Fe 2+ _Q complex respectively. After water_stress, the electron transport rate between Q A (primary quinone electron acceptor of PSⅡ)/Q B(secondary quinone electron acceptor of PSⅡ) was affected and the absorption doublets of Fe 2+ disappeared, suggesting that the reduced Cyt_b559 and Fe 2+ _Q complex had been oxidized. The results indicated that water_stress had changed the redox status of iron in the iron_quinone complex. Iron took part in electron transport through the change from a state of reduction to oxidation.
基金supported by the National Natural Science Foundation of China(No.50371057)
文摘Mssbauer spectrum and three dimensional atom probes（3DAP） were combined to investigate the mechanism of cementite dissolution in a cold-drawn eutectoid steel at a true strain of 2.89.The experimental results suggest that the dislocations play an important role in the dissolution of the cementite by sweeping across the nano-scaled cementite,and transferring carbon from cementite to ferrite inducing cementite decomposition.The mechanism of cementite dissolution in the steel is discussed in association with the investigation of nonstoichiometric cementite structure after heavy deformation.
基金supported by the National Natural Science Foundation Grant 49673186.
文摘The M?ssbauer spectra of natural megacrystal clinopyroxene are usually fitted by 4 sets of symmetric doublets, A-A', B-B', C-C' and D-D', respectively, in terms of increasing Qs value in literature. But the assignments of those doublets are quite different, except the D-D' doublet assigned to Fe3+at the lattice site M***1 in previous papers. Particularly, the assignment and interpretation of the C-C' doublet are diverse.
文摘Using 57 Fe Mssbauer effect, the chemical states of iron components were investigated for the barks of Platycladus orientalis, Cedrus deodara and Platanus acerifolia sampled from Lanzhou City, China. All bark samples showed two overlapping doublets with large and small quadruple splitting. Only Platycladus orientalis's barks exhibited one sextet. Based on Mssbauer parameters, they were attributed to paramagnetic ferrous, paramagnetic ferric and magnetic iron, respectively. For the sampling site which is about 6 kilometers from Lanzhou Steel Factory, the ratio of ferrous to ferric was higher in the sample of Platanus acerifolia's barks, whereas the barks of Platycladus orientalis and Cedrus deodara gave similar values of this ratio. Platycladus orientalis was the most effective in accumulating iron complexes in barks among the three trees. Platanus acerifolia's barks sampled at Lanzhou Steel Factory's area exhibited higher absolute intensities of iron components and lower ration of ferrous to ferric, indicating that industrial air pollution is a contributing factor in accumulating iron compounds in the tree barks of this region.
文摘Chemical bond properties of YBa 2Cu 3O 7 were studied by using the average ba nd-gap model. The calculated results show that the covalency of Cu(1)-O bond i s 0.406, and one of Cu(2)-O is 0.276. Mssbauer isomer shifts of 57Fe in Y-123 were calculated by the chemical surrounding factor h v defined b y covalency and electronic polarizability. The charge-state and site of Fe were determined. The relation between the coupling constant of electron-phonon inte raction and covalency is employed to explain that the Cu(2)-O plane is more im portant than the Cu(1)-O chain on the superconductivity in the Y-123 compound s.
文摘The martensite microstructure,amount of retained austenite and its carbon concentration in the 40CrNiMo steel quenched at various conditions have been investigated by using trans- mission Mossbauer spectroscopy at room temperature.It was shown that high-temperature quenching and thermomechanical quenching has little influence on amount of retained austenite,thus the toughening effect of quenching was attributed to bulk lath martensite and its refining.
文摘By using the chemical bond theory of dielectric description, the chemical bond parameters of (Tl, Pb) - 1223 was calculated. The results show that the Sr-O, Tl-O, and Ca-O types of bond have higher ionic character and the Cu-O types of bond have more covalent character. Mssbauer isomer shifts of 57Fe and 119Sn doped in (Tl, Pb) -1223 were calculated by using the chemical environmental factor, he, defined by covalency and electronic polarizability. Four valence state tin and three valence iron sites were identified in 57Fe, and 119Sn doped (Tl, Pb) -1223 superconductor. We conclude that all of the Fe atoms substitute the Cu at square planar Cu (1) site, whereas Sn prefers to substitute the square pyramidal Cu (2) site.
基金Project supported by the Second Stage of Brain Korea 21 ProjectProject(RTI04-01-03) supported by the Regional Technology Innovation Program of the Ministry of Knowledge Economy (MKE),Korea
文摘The effect of non-magnetic Al^3＋ ion doping on the magnetic properties of MnFe2-2x Al2xO4 （0 ≤x≤ 0.4） spinel ferrites was studied using Moessbauer spectroscopy measurements at room temperature. From the Moessbauer study, it is observed that the ：esolved hyperfine sextets are due to the distribution of Fe ions on the two sublattices of the spinel ferrites. The value of the isomer shift obtained from the fitting of the Moessbauer spectra indicates that Fe ions are in ＋3 state. A paramagnetic doublet is observed at ：iegree of inversion x=0.4, superimposed on the hyperfine sextets, indicating that the super-exchange interaction A-B decreases due to ：he dilution of sublattice by Al^3＋ ions. The hyperfine magnetic field decreases at both interstitial sites of tetrahedral （A） and 3ctahedral （B） with the increase in Al concentration.
文摘If recoilless fraction fa is available, the optimum absorber thickness dopt can be calculated by maximizing the signal to noise ratio or Q factor. In this work,an approach presented is to get experimental Qexp as a function of the thickness,andthen fitting Qexp by its theoretical expression gives fa value. At last the dopt value is deduced from a maximum on the fitted curve.In such a way, thicknesses of six specimens with quadrupole or magnetic hyperfinc splitting were optimized.
基金supported by the National Natural Science Foundation of China (Grant No. 10574059)the Natural Science Foundation of Gansu Province (Grant No. 0710RJZA074)+2 种基金the Scientific Research Project of Bureau of Education of Gansu Province (Grant No. 0711B-04)the Key Project of the Science and Technology Research of Ministry of Education (Grant No. 209127)the "Qing Lan" Talent Engineering Funds of Lanzhou Jiaotong University
文摘The effects of Al substitution for Fe on the structure, magnetics, magnetostriction, anisotropy and spin reorientation of a series of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys (x=0.05, 0.1, 0.15, 0.2, 0.25, 0.3) at room temperature have been investigated. The alloys of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 substantially retain MgCu2-type C-15 cubic Laves phase structure when x【0.2. The mixed phases appear with x = 0.2, and cubic Laves phase decreases with increasing x. The magnetostriction of the Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys decreases drastically with increasing x and the giant magnetostrictive effect disappears for x 】 0.15. Fortunately, a small amount of Al substitution is beneficial to a decrease in the magnetocrystalline anisotropy. The spin reorientation temperature decreases with increasing x. The analysis of the Mssbauer spectra indicates that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the increase of Al concentration x, namely, spin reorientation, resulting in the change of macroscopical magnetic properties and magnetostriction. The hyperfine field decreases, but the isomer shifts increases with Al concentration increasing and the quadruple splitting QS shows a weak concentration dependence.
文摘A few valuable results have been obtained by making use of the M(?)ssbauer effect in the study of ancient wares. However, rarely is this technique applied to study ancient porcelain. Ru kiln is one of the five famous kilns (Ru, Jun, Guan, Ge and Ding kilns) made in Chinese Song Dynasty (A. D. 960—1279 ). It has high artistic value but there are only
文摘Grandidierite MgAl<sub>3</sub>BSiO<sub>9</sub> is a rare island silicate with extra anion [BO<sub>3</sub>]. It was firstly found in granities in the south Madagascar and associated with orthoclase, microcline, almandine, hercynite and tourmaline etc. Then it was reportedly found in Hungary （1918）. The mineral firstly found in China was produced in gneiss of M ashan Group, the Sandaogou area of Jixi City of Heilongjiang Province. The long pale bluish green column of the metamorphic mineral was 0.8—4.0 mm in length and associated with bytownite,
文摘Since J. Reilly et al. reported their research achievements on FeTi and its hydrides for the first time in 1974, extensive attention and wide interest of relevant research groups have been stimulated. The various phase compositions and their formation mechanism on FeTiH<sub>x</sub> materials have not been understood completely until now. p. Raj’s work is worth putting forward. He considered that the Fe-H bonding interaction played an important role in the transformation of FeTiH<sub>x</sub> from the β<sub>2</sub> to the γ-phase.
基金Project supported by the National Natural Science Foundation of China.
文摘I. INTRODUCTIONIon-implantation technique is a new technique developed in recent years. It was first applied to semiconductor devices in the 1960s, and then widespread into many fields such as solid state physics and material science. However, only a
基金Project supported by the National Natural Science Foundation of China.
文摘Since the theory of spinodal decomposition in a supersaturated solid solution was formulated by Hillert and Chan, the phenomena of spinodal decomposition have been found in many alloys. We found a modulated structure in 10Ni maraging steel. Some investigators suggested that the formation of a modulated structure does not always imply the spinodal decomposition, and the modulated structure could also result from nucleation and growth.
文摘Ⅰ. INTRODUCTION Since the discovery of recoil-less resonance and absorption of low γ-rays-M(?)ssbauer effect, the meteorites were first investigated using the M(?)ssbauer spectra by Sprenkel-Segtl et al. in 1964.
文摘1 Introduction That molecular properties depend on its structure is one of the central ideas of chemistry. As a first order approximation, topological structure, that is. the atomic constitution and its linkage in a molecule, may be taken into account. It has been known for a long time to the chemists, that more quantitative expressions of them, which are now so-called molecular topological indices, however, were not fully developed until recently.
文摘^(57)Fe Mssbauer spectroscopy was used to study the mechanism and regularity of coal desulfurization by microwave irradiation combined with magnetic-separation and with chemical acid-leaching. The results of phase analyses show that the decomposing reaction of pyrite intrinsic in coal, caused by the selective dielectric heating of microwave electromagnetic energy, FeS_2→Fe_(1-x)S→FeS, consecutively progresses towards the right-hand side with increased irradiation time. The whole process of microwave desulfurization of raw coal consists of the initiation, the promotion, and the saturation stages. The optimum desulfurization efficiency for microwave irradiation combined with magnetic-separation treatment and with chemical acid-leaching treatment can be attained by appropriately controlling the irradiation time to enable the corresponding microwave treatment to lie in the promotion stage and the saturation stage, respectively.
