Fixed charge and interface traps at heterovalent interfaces between Si(1 0 0) and non-crystalline Al2O3–Ta2O5 alloys

Characterization by Auger electron spectroscopy (AES) and Fourier transformation infrared spectroscopy (FTIR) confirms (Ta₂O₅)_x(Al₂O₃)_1−x alloys are homogeneous pseudo-binary alloys with increased thermal stability with respect to end member oxides, Ta₂O₅ and Al₂O₃. Capacitance–voltage (C–V) and current density–voltage (J–V) data as a function of temperate show that the Ta d-states of the alloys act as localized electron traps, and are at an energy approximately equal to the conduction band offset of Ta₂O₅ with respect to Si.     

Disorder broadening of alloy Auger spectra

Auger spectroscopy promises the means to separate initial and final state contributions to the disorder broadening of core XPS spectra in disordered alloys. Auger disorder broadening, deduced from recent ab initio results, is predicted to be greater than XPS disorder broadening for Cu₅₀Pd₅₀ and Ag₅₀Pd₅₀ alloys. Simulations are used to assess whether this effect is observable experimentally despite the greater lifetime broadening of Auger spectra. A number of cases where narrow core–core–core Auger transitions should allow clear experimental identification of this effect are identified. The prospects for determining environment-resolved Auger spectra using APECS have been investigated.     

电阻率与强度性能的关联及铜合金性能分区

铜合金以低电阻率为特征,由于电阻率与强度存在着共同的微观结构机理,两者往往协同变化,而导致难以对合金进行性能的全面评估和选材.本文以Cu-Ni-Mo合金作为研究对象,以团簇结构[Mo_1-Ni_(12)]构建固溶体的近程序结构模型,解析了电阻率和强度依赖于成分的定量变化规律,并定义了拉伸强度/电阻率的值为代表合金本质特性的"强阻比",得到了完全固溶态Cu-Ni-Mo合金的强阻比为7×10~8MPa/?·m,完全析出态的强阻比为(310—490)×10~8MPa/?·m.进而应用强阻比对常用铜合金进行了性能分区,给出铜合金材料选材的依据,得出了基于Cu-(Cr, Zr, Mg, Ag, Cd)等二元基础体系的铜合金适用于高强高导应用,而基于Cu-(Be, Ni, Sn, Fe, Zn, Ti, Al)等为基础二元体系的铜合金不能实现高强高导.该强阻比为310的特征性能分界线的发现为合金性能的全面评估提供了量化依据,可指导高强高导铜合金的选材和研发.     

Study of the chemical bonding of titanium with silicon and oxygen by AES and SEELS

Auger electron Spectroscopy (AES) and slow electron energy loss Spectroscopy (SEELS) have been employed to study the electronic structure of Ti, TiSi₂ and TiO₂. The changes in the Auger and loss spectra when Ti chemically binds with silicon to form TiSi₂ and with oxygen to form TiO₂ have been understood as manifestations of changes in electronic participation. AES spectra show distinct changes in line shapes of transitions involving the Ti valence electrons. The SEELS spectra provide information regarding shallow core levels, valence band and the collective excitation energies of the volume and surface plasmons. By monitoring the changes in the Auger peak at 387 eV and the 3p→ 3d quasiatomic transition (at about 45 eV), the role of d-orbital occupancies are studied in Ti and its compounds. The SEELS studies in the 0-80 eV range have enabled the authors to observe the behaviour of the 3p → 3d quasiatomic transition in Ti, which persists after oxidation but almost disappears during TiSi₂ formation. The values of the plasmon losses are related to the collective behaviour of conduction electrons.     

A contribution to the invar problem by hyperfine field distribution analyses

The Mössbauer spectra of Invar type Fe₆₅(Ni_1-xMn_x)₃₅ alloys (0 x 0.3) were analyzed to yield hyperfine field distribution (P(H)) curve. The P(H) curves of the alloy with x = 0, that is the “classical” Invar alloy, at 4.2 K is character ized by a relatively sharp main peak at 350 kOe and a weak low field component around 50 kOe. With increasing x, the low field component grows and the high field main peak spreads toward a low field. By raising temperature, the main peak exhibits a remarkable broadening as well as a decrease in the average internal field and a growth of the low field component has not been detected. On the basis of these observations, models of the Invar alloy so far proposed are discussed.     

Magnetostriction and spin reorientation in ferromagnetic Laves phase Pr(Ga_xFe_(1-x))_(1.9) compounds

The magnetostriction, magnetization, and spin reorientation properties in Pr(Ga_xFe_(1-x))_(1.9) alloys have been investigated by high-precision x-ray diffraction(XRD) step scanning, magnetization, and Mo¨ssbauer spectra measurements. Ga substitution reduces the magnetostriction(λ_(||)) with magnetic field H ≥ 8 kOe(1 Oe = 1.33322×10~2 Pa), but it also increases the λ|| value when H ≤ 8 kOe at 5 K. Spin-reorientations(SR) are observed in all the alloys investigated, as determined by the step scanned XRD, Mo¨ssbauer spectra, and the abnormal temperature dependence of magnetization. An increase of the spin reorientation temperature(T_(SR)) due to Ga substitution is found in the phase diagram, which is different from the decrease one in many R(T_x Fe_(1-x))_(1.9)(T = Co, Al, Mn) alloys. The present work provides a method to control the easy magnetization direction(EMD) or T_(SR) for developing an anisotropic compensation system.     

Phase formation and magnetic properties of Nd2Fe14B-type Nd16Co76B8−xCx alloys and their hydrides

An attempt is made to synthesize Nd₂Co₁₄C compound by mechanical alloying Nd₁₆Co₇₆B_8−xC_x (0x8) alloys and subsequent annealing. Phase formation and magnetic properties of Nd₂Fe₁₄B-type Nd₁₆Co₇₆B_8−xC_x alloys and their hydrides are investigated. The Nd₂Co₁₄(B,C) phase with Nd₂Fe₁₄B-type structure is formed for Nd₁₆Co₇₆B_8−xC_x (0x7) alloys, while NdCo₇C_δ phase with TbCu₇-type structure is observed in Nd₁₆Co₇₆C₈ alloy. The lattice parameter c of the Nd₂Co₁₄(B,C) phase decreases with increasing the carbon content. A limit volume of the unit cell to form the Nd₂Fe₁₄B-type structure is estimated to be 0.870 nm³. The spin-reorientation temperature T_SR increases with increasing the carbon content, due to an enhancement of magnetocrystalline anisotropy caused by carbon substitution for boron. After hydrogenation, the lattice expansion is observed for Nd₁₆Co₇₆B_8−xC_x (0x7) alloys. The spin-reorientation temperature of Nd₁₆Co₇₆B_8−xC_xH_y (0x7) is much lower than that of the host alloys. Some structural and magnetic properties of hypothetic Nd₂Co₁₄C and Nd₂Co₁₄CH_y compounds are estimated by extrapolation.     

A study of atomic iodine and molecular thallium iodide by X-ray photoelectron and auger electron spectroscopy

The I3d5/2 binding energy has been measured in atomic iodine, thallium iodide and cesium iodide by high temperature gas-phase photoelectron spectrscopy using Al K (1486.6 eV) X-rays. The iodine M₅N_4,5N_4,5 (¹G₄) Auger energies for TlI and CsI have also been measured and combined with binding energies to yield extra-atomic relaxation energies of 0.5 and O.3 eV, respectively, after corrections are applied to the Auger parameter. Charges were calculated using the simple potential model, which was also used to obtain an estimate of the atomic T14f binding energy. Two other estimates of the atomic T14f7/2 binding energy have also been calculated, both based on Dirac-Fock ΔSCF binding energies. The results of the three methods suggest a value of 125.3 ± 0.2 eV for T14f7/2.     

High-resolution KLM Auger spectra of Ni metal excited by X-rays

KLM Auger spectra of Ni metal were measured with high energy resolution and high statistical accuracy using monochromatic synchrotron radiation. The spectra were corrected for the background from inelastically scattered electrons using partial intensity analysis where the electron trajectories were calculated by Monte Carlo simulation. Following background correction, the corrected spectra were fitted to model peaks taking into account intrinsic excitations. The measured transition energy of the most intense KL₂M₃ (¹D₂) Auger line is 7388.1 eV (0.4). The obtained relative intensities and energies of the Auger diagram lines are compared to published calculations as well as to experimental data for other 3d transition metals. In addition, the presence of Ni 3s, 3p photoelectron peaks in the spectra excited internally by Ni K X-rays is shown.     

Mg-Y-Zn合金三元金属间化合物的电子结构及其相稳定性的第一性原理研究

采用基于密度泛函的第一性原理平面波赝势方法计算Mg-Y-Zn合金三元金属间化合物X-Mg₁₂YZn 相和W-Mg₃Y₂Zn₃相的晶格常数、形成焓和电子结构. 形成焓的计算结果表明, X-Mg₁₂YZn相和W-Mg₃Y₂Zn₃相都具有负的形成焓, 并且W-Mg₃Y₂Zn₃相的形成焓更低; 电子结构的计算分析表明, W-Mg₃Y₂Zn₃相成键峰主要来自Mg的2p轨道、Zn的3p轨道和Y的4d轨道的贡献. 而X-Mg₁₂YZn相成键峰主要来自Mg的3s和2p轨道、Zn的3p轨道和Y的4d轨道的贡献. 对W-Mg₃Y₂Zn₃相(011)面和X-Mg₁₂YZn相(0001)面的电荷密度分析表明, 两相中Zn-Y原子间都形成了共价键, 且W-Mg₃Y₂Zn₃相的共价性比X-Mg₁₂YZn相的共价性更强. 在费米能级低能级处, W-Mg₃Y₂Zn₃相具有更多的成键电子数, 决定了W-Mg₃Y₂Zn₃相比X-Mg₁₂YZn相有更好的相稳定性.     

Paraconductivity study in ErBa_2Cu_(3-x)M_xO_(7-δ)(M=Zn,Fe) superconductors

We report here the paraconductivity of ErBa_2Cu_(3-x)M_xO_(7-δ)(M=Zn, Fe) superconductors.The logarithmic plots of excess conductivityσand reduced temperatureCreveal two different exponents corresponding to crossover temperature as a result of shifting the order parameter from 2 to 3.The first exponent in the normal field region is close to1,in which the order parameter dimensionality(OPD)is 2.The second exponent in the critical field region is close to 0.5,in which the OPD is 3.The coherence length,interlayer coupling,interlayer separation and carrier concentration decrease with increasing doping content,and their values for Fe samples are different from those of Zn samples.While anisotropy is increased with increasing doping content,it is generally higher for a Zn sample than that for an Fe sample.We also estimate several physical parameters such as upper critical magnetic fields in the a–b plane and along the c axis(Baband Bc),and critical current density J at 0 K.Although Baband Bcare generally increased with doping content increasing,the value of Babis found to be twice more than that of Bc.A similar behavior is obtained for J(0 K)and its value is higher in the Fe sample than that in the Zn sample.These results are discussed in terms of oxygen deficiency,localization of carriers,and flux pinning,which are produced by doping.     

Auger-vacancy satellites in the decay of 82Pb (RaD)

The L-Auger spectrum of ²¹⁰Bi from RaD (²¹⁰Pb) has been studied with a resolution of 0.18% and a very thin source but with some sacrifice in statistics. A total of 65 lines or line groups have been wholly or partially identified. The L₃-MM lines, most of which result from filling L₃ vacancies created by the L₁-L₃M_{4, 5} Coster-Kronig process, are displaced an average of −36±5 eV with respect to the energies expected from the L_{1, 2}-MM spectra. This effect is the Auger analogue of the phenomenon of X-ray satellites. The L₃-M₄M₅ and L₃-M₅M₅ displacements agree within experimental error with predictions from the displacements of the strongest L₁ and L₂ X-ray satellites. We suggest the term Auger-vacancy satellites for these displaced Auger lines to distinguish them from the weak lines of the K-LL spectrum for which we suggest the term Auger Intermediate-Coupling Satellites. The ratio (L₁-M₄M₅ Auger Line)/L₁-vacancies = R = 32.5±3.5, which may have importance in determining L₁ capture as distinct from L-capture, was also measured for the first time. The end-point of the low-energy beta spectrum of ²¹⁰Pb was found to be 17.0±0.5 keV.     

ICP-MS法分析不同种质荒漠肉苁蓉矿质元素分布特征

矿质元素是中药材品质评价的重要指标之一,与中药材功效物质合成及其功效的发挥密切相关,中药材矿质元素含量受其种质、采收时期、药用部位、产地等因素的影响。荒漠肉苁蓉是我国著名补益中药,也是药食同源类药材,其矿质元素含量越来越受到人们关注。应用ICP-AES法测定了黄花、白花、紫花三种类型荒漠肉苁蓉不同部位4种常量矿质元素和8种微量矿质元素含量。结果表明：(1)不同类型荒漠肉苁蓉均含有K、 Ca、 Mg、 Na、 Fe、 Mn、 Cu、 Zn、 Cr、 As、 Pb和Cd元素,但不同类型荒漠肉苁蓉矿质元素含量差异较大,黄花肉苁蓉矿质元素含量低于白花肉苁蓉和紫花肉苁蓉;白花肉苁蓉K、 Ca、 Mg、 Na、和Cu含量高于紫花肉苁蓉,而Zn、 Cr和Cd含量低于紫花肉苁蓉。(2)荒漠肉苁蓉中12种矿质元素分布特征差异明显,K、 Ca、 Mg、 Na和Cu主要分布在上部。(3)荒漠肉苁蓉不同部位矿质元素比值差异显著,三种类型荒漠肉苁蓉K/Na值均为下部>中部>上部;Mg/Fe值紫花、白花类型中部最高,黄花类型上部最高;Zn/Mn比值紫花和黄花类型中部最高,而白花类型下部最高;Cu/Cr...     

NaZnLa(PO4)2中Ce3+和Tb3+的发光

采用高温固相反应合成了NaZnLa(PO₄)₂中掺杂Ce³⁺、Tb³⁺的荧光体,对其晶体结构、发光行为进行了研究,并尝试对NaZnLa(PO₄)₂:Ce,Tb荧光体进行调制。NaZnLa(PO₄)₂是LaPO₄的同构物,为单斜晶系独居石结构,从XRD谱数据得到NaZnLa(PO₄)₂基质的晶胞参数为a=0.6823nm,b=0.7045nm,c=0.6497nm,β=1039°,v=0.303nm³,其晶胞参数与单斜LaPO₄的晶胞参数相似。在NaZnLa(PO₄)₂:Ce,Tb荧光体中,Ce³⁺对Tb³⁺有良好的敏化作用,掺杂适量的BO₃^3-、Al³⁺、Dy³⁺,可以增强发光亮度。     

Analysis of the Zeeman effect on D_α spectra on the EAST tokamak

Based on the passive spectroscopy,the D_α atomic emission spectra in the boundary region of the plasma have been measured by a high resolution optical spectroscopic multichannel analysis(OSMA) system in EAST tokamak.The Zeeman splitting of the D_α spectral lines has been observed.A fitting procedure by using a nonlinear least squares method was applied to fit and analyze all polarization π and ±σ components of the D_α atomic spectra to acquire the information of the local plasma.The spectral line shape was investigated according to emission spectra from different regions(e.g.,low-field side and high-field side) along the viewing chords.Each polarization component was fitted and classified into three energy categories(the cold,warm,and hot components) based on different atomic production processes,in consistent with the transition energy distribution by calculating the gradient of the D_α spectral profile.The emission position,magnetic field intensity,and flow velocity of a deuterium atom were also discussed in the context.     

Effect of substrate bias on SE, XPS and XAES studies of diamond-like carbon films deposited by saddle field fast atom beam source

This paper reports the effect of positive substrate bias (V_s) varying from 0 to 180 V on the spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS) and X-ray Auger electron spectroscopy (XAES) studies of diamond-like carbon (DLC) films deposited using CH₄ gas as a feedstock into a saddle field fast atom beam (FAB) source. The values of optical constants like refractive index (n) and extinction coefficient (k) of the deposited DLC films were determined using a two phase model. The values of ‘n’ were found to fall in the range from 1.505 to 1.720 and ‘k’ from 0.03 to 0.125 by application of different values of V_s. Value of these optical constants were found to decrease with the increase of substrate bias up to 90 V and then increase beyond this value. Position of C 1s peak evaluated from XPS data was found to occur at 286.09±0.18 eV in DLC films deposited by application of different values of V_s. Observation of full width at half maximum (FWHM) (τ) value (1.928 eV at V_s=0 V, 2.0 eV at V_s=90 V and 1.89 eV at V_s=180 V) clearly hinted the existence of a point of inflection in the properties of DLC films deposited using FAB source this way. A parameter ‘D’ defined as the distance between the maximum of positive going excursion and the minimum of negative going excursion was calculated in the derivative XAES spectra. The values of ‘D’ evaluated from XAES data for DLC films were found to be 14.8, 14.5 and 15.2 at V_s=0, 90 and 180 V, respectively. The sp² percentage was calculated for samples deposited this way and was found to be low and lie approximately at 5.6, 2.8, 2.3, 5.7 and 11.5 for different values of V_s=0, 50, 90, 150 and 180 V. The sp³ content percentage and sp³/sp² ratio was found to be 94.4 and 16.7, 97.7 and 42.5 at V_s=0 and 90 V, respectively. Beyond V_s=90 V these values started decreasing. Mainly, a point of inflection in all the properties of DLC films studied over here at around 90 V of applied substrate bias has been observed, which has been explained on the basis of existing theories in the literature.     

Diffusion of silicon in Fe-based amorphous and crystalline alloys

The segregation rate of silicon was measured in three different Fe-based amorphous and crystallized alloys with different silicon contents: 3.5, 5 and 9 at%. Analysis of the segregation kinetics yielded the diffusion activation energies E, as well as the frequency factors D₀. A linear dependence was found between In D₀ and E. In general, the D₀ and E values were lower for the amorphous specimens than for the crystalline ones, were independent of silicon content and are explained in terms of an oversaturated concentration of structural defects. In the crystalline specimens, diffusion behaviour was influenced by silicon content near the solubility limit of silicon in iron.     

Core-level Auger spectroscopy of the 4d metals

We report some of the results of extensive experimental and theoretical studies by our group of the high energy Auger spectra of the 4d metals and some of their alloys. We consider, separately, three aspects of these spectra: comparison of experiment with atomic theoretical calculations; the relationship between the Auger kinetic energies and the screening mechanisms in these metals; and the unique properties of satellites associated with these spectra, especially with the L_1,2,3M_4,5M_4,5 spectra. Comparison with atomic theory yields some discrepancies that should be taken into account in the formulation of the theories. Consideration of the Auger kinetic energies yields insight into screening mechanisms and suggests methods for extracting electronic structure changes in alloys from XPS and XAES shifts. Systematic studies of the satellites permit their identification as arising from shake-up processes without contributions from of Coster–Kronig processes, in contrast to studies of 3d metals, such as Cu. Synchrotron studies allow the observation of the transition from the adiabatic approximation regime to that of the sudden approximation.     

面心立方固溶体合金的团簇加连接原子几何模型及典型工业合金成分解析

工业合金牌号的成分选择体现了固溶体合金的化学短程有序结构,满足由最近邻两层原子组成的"团簇加连接原子"模型,例如对于置换型面心立方固溶体Cu-Zn,其合金牌号成分可以表述为[Zn-Cu_(12)]Zn_(1-6)和[Zn-Cu_(12)](Cu,Zn)_6,其中方括号内为第一近邻配位多面体团簇.基于此,本文赋予团簇式以具体原子结构的含义,对置换型面心立方固溶体结构中团簇的可能存在形式进行了穷尽,得出团簇式所对应的所有"团簇加连接原子"结构单元模型,给出团簇和连接原子之间的比例和空间排列的所有可能,并对Cu-Zn和Cu-Ni合金常用牌号对应的团簇式给出了三维结构模型,进一步验证了前期关于合金团簇式解析的正确性.用这些模型中原子化学序描述合金的成分,赋予团簇式以具体的原子结构意义,为进一步开发新的合金提供了理论依据.     

MSO4:Eu2+(M =Mg,Ca, Sr,Ba)的等电子陷阱与热释光特性

在硫酸盐掺入稀土元素的研究中, 得到了几种掺入Eu²⁺的碱土金属硫酸盐磷光体MSO₄:Eu²⁺ (M =Mg, Ca, Sr, Ba), 这组磷光体具有与掺入三价稀土离子(Tm³⁺, Dy³⁺, Eu³⁺)的碱土金属硫酸盐截然不同的热释光特性, 热释光三维发光谱中只呈现一个热释光峰, 对γ和βup辐射的热释光剂量响应为线性-亚线性响应. 结果清楚地显现出Eu²⁺对碱土金属阳离子的等价取代而形成的等电子陷阱对这些磷光体的热释光特性起了关键性的作用, Eu²⁺等电子陷阱与基质中的本征缺陷SO₄^2-形成的缺陷复合体作为热释光多阶段过程的基本作用单元, 基本上产生一次作用热释光事件. SrSO₄:Eu²⁺是一种典型的等电子陷阱发光的磷光体, 它具有相当高的热释光和光释光发光效率.