2001 Vol. 25, No. S1
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Abstract:
A multiple parallel plate Aluminum ionization chamber has been designed.Using the ionization chamber the measurement dose gradient distribution at and near the interface of Kovar/Au/Al,Pb/Al,Ta/Al has been done for 30—100keV Beijing synchrotron radiation facility x-rays and DEF(Dose Enhancement Factor)are provided.Complementary metal-oxide semiconductor (CMOS) 4069 devices are irradiated by hard x-rays in BSRF with emphasis on the relative dose-enhancement factor.Using Bi-laminate structure,the equivalent relation of total dose damage is setup by comparing the response of devices,damage enhancement factor of the device is provided.These methods are provided for X-rays radiation hardening technology as an effective evaluation approach.
A multiple parallel plate Aluminum ionization chamber has been designed.Using the ionization chamber the measurement dose gradient distribution at and near the interface of Kovar/Au/Al,Pb/Al,Ta/Al has been done for 30—100keV Beijing synchrotron radiation facility x-rays and DEF(Dose Enhancement Factor)are provided.Complementary metal-oxide semiconductor (CMOS) 4069 devices are irradiated by hard x-rays in BSRF with emphasis on the relative dose-enhancement factor.Using Bi-laminate structure,the equivalent relation of total dose damage is setup by comparing the response of devices,damage enhancement factor of the device is provided.These methods are provided for X-rays radiation hardening technology as an effective evaluation approach.
Abstract:
Based on the XAFS experimental station,jointed with the user team,we have made effort to develop new experimental methods,to expand the applications of this method.Those efforts include the XAFS of melting status; the total reflection XAFS and XEOL-XAFS.The principle,the experiment and the result of each of those methods are briefly introduced and a short discusses for the results are also given in this paper.
Based on the XAFS experimental station,jointed with the user team,we have made effort to develop new experimental methods,to expand the applications of this method.Those efforts include the XAFS of melting status; the total reflection XAFS and XEOL-XAFS.The principle,the experiment and the result of each of those methods are briefly introduced and a short discusses for the results are also given in this paper.
Abstract:
The long-rang and local structures of the Nd9Fe85－xB6Mnx(x=0.5,1.0)nanocomposite produced at melt spinning speed of 20m/s have been investigated by X-ray absorption fine structure(XAFS) and X-ray diffraction (XRD).The crystallized samples were annealed at temperatures 700°C for 5 minutes with a high heating rate.The results show that in the initial samples,the structures of the Nd9Fe85－xB6Mnxmanocomposite were strongly correlated with the addition of Mn atoms.Following the increase of Mn content,the long-range and local orders of the Nd9Fe85－xB6Mnxnanocomposite increase,and a soft magnetic phase of α-Fe and a hard magnetic phase of Nd2Fe14B were formed at the addition of 1% Mn.However,the addition of element Mn can not lead to the generation of new phases or the deeper crystallization for the Nd9Fe85－xB6Mnxnanocomposite.We consider that during the preparation,element Mn was alloyed into the main lattice of the Nd9Fe85－xB6Mnxnanocomposite with a metastable structure; through annealing,the Mn atoms were separated from the initial main lattice to the borders of crystalline grain.
The long-rang and local structures of the Nd9Fe85－xB6Mnx(x=0.5,1.0)nanocomposite produced at melt spinning speed of 20m/s have been investigated by X-ray absorption fine structure(XAFS) and X-ray diffraction (XRD).The crystallized samples were annealed at temperatures 700°C for 5 minutes with a high heating rate.The results show that in the initial samples,the structures of the Nd9Fe85－xB6Mnxmanocomposite were strongly correlated with the addition of Mn atoms.Following the increase of Mn content,the long-range and local orders of the Nd9Fe85－xB6Mnxnanocomposite increase,and a soft magnetic phase of α-Fe and a hard magnetic phase of Nd2Fe14B were formed at the addition of 1% Mn.However,the addition of element Mn can not lead to the generation of new phases or the deeper crystallization for the Nd9Fe85－xB6Mnxnanocomposite.We consider that during the preparation,element Mn was alloyed into the main lattice of the Nd9Fe85－xB6Mnxnanocomposite with a metastable structure; through annealing,the Mn atoms were separated from the initial main lattice to the borders of crystalline grain.
Abstract:
The co-precipitated ZnO/γ-Al2O3system calcined under 200°C,300°C,450°C and 800°C was studied here using XRD and EXAFS and the Zn-centered Radial Distribution Functions were obtained.The nearest Zn-O shell was fitted and a conclusion was drawn that the Zn is coordinated by 4 oxigen atoms,just like within the original ZnO crystal.The changing tendency of RDF peaks of the second Zn-centered shell with the ZnO loading was also discussed.
The co-precipitated ZnO/γ-Al2O3system calcined under 200°C,300°C,450°C and 800°C was studied here using XRD and EXAFS and the Zn-centered Radial Distribution Functions were obtained.The nearest Zn-O shell was fitted and a conclusion was drawn that the Zn is coordinated by 4 oxigen atoms,just like within the original ZnO crystal.The changing tendency of RDF peaks of the second Zn-centered shell with the ZnO loading was also discussed.
Abstract:
Photoemission spectroscopic experiment is one of most important method amongst the experimental methods used to study electronic structures of condensed matter as well as thin films. Data acquisition and proper treatment of the photoemission experimental data are indispensable processes to draw intrinsic information of the electronic structure of the target matter.In this paper we discuss the experimental modes under angle integrated photoemission condition and the problem for further data treatment obtained under energy distribution curve mode using synchrotron radiation photoemission spectroscopy.
Photoemission spectroscopic experiment is one of most important method amongst the experimental methods used to study electronic structures of condensed matter as well as thin films. Data acquisition and proper treatment of the photoemission experimental data are indispensable processes to draw intrinsic information of the electronic structure of the target matter.In this paper we discuss the experimental modes under angle integrated photoemission condition and the problem for further data treatment obtained under energy distribution curve mode using synchrotron radiation photoemission spectroscopy.
Abstract:
Valence band photoemission experiments on Pr1-xSrxMnO3polycrystalline system with x ranging from 0.0 to 0.4 show that the density of states of the bands appearing in the ranges between Fermi level and ～12eV below Fermi level have a substantial change with the doping level x.These features are discussed in terms of charge transfer in the ground states of Pr1-xSrxMnO3system.A nonlinear charge transfer with the doping amount x is evidenced and a possible second order phase transition mediated by the charge transfer is proposed.
Valence band photoemission experiments on Pr1-xSrxMnO3polycrystalline system with x ranging from 0.0 to 0.4 show that the density of states of the bands appearing in the ranges between Fermi level and ～12eV below Fermi level have a substantial change with the doping level x.These features are discussed in terms of charge transfer in the ground states of Pr1-xSrxMnO3system.A nonlinear charge transfer with the doping amount x is evidenced and a possible second order phase transition mediated by the charge transfer is proposed.
Abstract:
Synchrotron radiation photoemission spectra were measured along the [111] direction of K3C60single crystal film at 190K,200K and 300K.Conduction band dispersions can be observed at 190K,and the band structure was nearly the same as that at 150K corresponding to the onedimensional-disordered orientaltional structure (IDDS) of K3C60.When the sample temperature increased to 220K,most subpeaks of the conduction band vanished and the dispersions could not be observed.This result coincides with the existence of an orientational phase transition occurred at 200K.The fcc nearest-neighbor antiferromagetic Ising model was found to be suitable to analyz the temperature dependence of the band structure.The phase transition is due to the onedimensional-disordered orientational structure at lower temperatures turned to be the mixture of BDS domains and disordered molecules at higher temperatures.The number of disordered molecules was deduced to be about 40 percent of the total molecular number at 220K.At room temperature,the electronic structure was drastically different from that at low temperatures because of the dynamical disorder of C60molecules.
Synchrotron radiation photoemission spectra were measured along the [111] direction of K3C60single crystal film at 190K,200K and 300K.Conduction band dispersions can be observed at 190K,and the band structure was nearly the same as that at 150K corresponding to the onedimensional-disordered orientaltional structure (IDDS) of K3C60.When the sample temperature increased to 220K,most subpeaks of the conduction band vanished and the dispersions could not be observed.This result coincides with the existence of an orientational phase transition occurred at 200K.The fcc nearest-neighbor antiferromagetic Ising model was found to be suitable to analyz the temperature dependence of the band structure.The phase transition is due to the onedimensional-disordered orientational structure at lower temperatures turned to be the mixture of BDS domains and disordered molecules at higher temperatures.The number of disordered molecules was deduced to be about 40 percent of the total molecular number at 220K.At room temperature,the electronic structure was drastically different from that at low temperatures because of the dynamical disorder of C60molecules.
Abstract:
The escape peaks in synchrotron radiation X-ray fluorescence (SR-XRD) spectra generating from Si(Li) detector can disrupt seriously the qualitative and quantitative analysis.Discrimination to escape peaks in experiments was performed.The escape peak position and intensity of 12 elements from K Kαto As Kα,for each of the 14 specimens,are measured.The differences of standard and experimental values of escape peak and the nearest major peak are compared.The errors are less than 10% in general.The ratios of intensity of escape peak and major peak are calculated using a simplified emitting distribution model of Si Kαexcited by X-ray.The ratios,both calculated and experimental,descend appro
The escape peaks in synchrotron radiation X-ray fluorescence (SR-XRD) spectra generating from Si(Li) detector can disrupt seriously the qualitative and quantitative analysis.Discrimination to escape peaks in experiments was performed.The escape peak position and intensity of 12 elements from K Kαto As Kα,for each of the 14 specimens,are measured.The differences of standard and experimental values of escape peak and the nearest major peak are compared.The errors are less than 10% in general.The ratios of intensity of escape peak and major peak are calculated using a simplified emitting distribution model of Si Kαexcited by X-ray.The ratios,both calculated and experimental,descend appro