原位统计分布分析——材料研究及质量判据的新技术

原位统计分布分析系指较大尺度范围内各化学组成及其形态的定量统计分布规律的分析技术.以火花光谱无预燃连续激发高速采集解析技术为基础研究成功的金属原位分析仪能有效地实现金属材料的原位统计分布分析.原位统计定量分布分析技术可以获得的关于材料的许多新信息.例如,各元素在材料中不同位置含量的统计定量分布;材料中各元素的偏析度的准确定量计算;元素在材料中不同含量所占的原位权重比率;材料的疏松度的定量表征;材料中夹杂物的统计定量分布以及材料中不同粒度夹杂物的统计定量分布等.随着金属原位分析仪的推广和应用,将为材料及工艺研究提供更多反映材料内在质量的新判据方法.     

钆的激光诱导击穿光谱原位统计分布分析

采用LIBS-OPA对取自不同电迁移部位的金属钆棒的纵剖面进行了原位统计分布分析,探讨了电迁移工艺中不同位置处的杂质元素在其电迁移方向上的分布规律。发现在电迁移工艺上部Ti和Cu的偏析较为严重,而下部即阴极附近的杂质元素含量大大降低且其分布趋于均匀。Ti和Al两个元素在电迁移末端含量发生较大变化,出现了一条明显的分界线,说明金属钆中的某些成分组成发生了突变,因此导致其分布发生了较大改变。而Cu,Si,Mo和Fe强度也都发生了不同程度的下降。但其偏析度变化不明显。Ti和Mo是金属钆的原位分析中出现异常信号较多的元素,说明金属Gd中存在一些Ti和Mo的化合物。采用透射电镜对金属钆棒中的化合物进行了观察,其结果与LIBS-OPA统计的结果较为相符。     

激光剥蚀高分辨电感耦合等离子体质谱的表面成像技术在钢板线状缺陷分析中的应用探讨

采用激光剥蚀高分辨电感耦合等离子体质谱(LA-HR-ICPMS)技术得到与钢铁材料表面线状缺陷及缺陷周围正常部位的上万个元素质谱信号,与实际样品位置信息比对,各信号与样品表面原始位置相对应,反映样品表面各成分的二维统计分布信息。用该表面成像技术获得的钢板表面线状缺陷区域元素分布结果与电子探针X射线显微分析（EPMA）、激光剥蚀飞行时间质谱（LA-TOF-MS）分析结果一致。该方法具有激发斑点适中、微损、原位分析、检测限低、二维成像直观显示的特点,解决了传统表面微区分析技术检测限偏高、激发斑点过小的问题,可作为表面线状缺陷异常元素甄别的有力工具,为寻找缺陷成因、改进工艺提供依据。     

硫化锰夹杂物面积与激光诱导击穿光谱信号强度关系的统计分析

在风电主轴上制取金相试样(材料牌号34CrNiMo6),用激光诱导击穿光谱仪(LIBS)扫描分析了抛光表面上S、Mn、Fe、Cr、Mo、Si和Al等元素的二维分布。使用金相显微镜对比扫描分析前后的金相照片,提取了各烧蚀点覆盖区域的MnS夹杂物形貌,获得了S和Mn两元素异常信号分布特征及对应激发区域内的MnS夹杂物面积数据,分析了夹杂物面积与信号强度之间的关系。结果表明,S和Mn两元素基本都在相同位置出现异常信号,且两元素的异常信号强度具有明显的线性相关性,材料中的MnS夹杂物是引发S和Mn出现异常信号的最主要来源,并且MnS夹杂物面积与S和Mn两元素的异常信号强度之间存在较强的线性相关性,可以通过对异常信号的分析来识别MnS夹杂物并确定其尺寸及分布状态。通过建立简化物理模型,计算了MnS夹杂物面积与S和Mn两元素含量之间的关系,在低含量段,得到了夹杂物面积与S和Mn两元素含量之间近似呈线性关系的结果,进而验证了S和Mn两元素异常信号强度与MnS夹杂物面积之间线性相关的实验结果。分析认为,元素的宏微观偏析、夹杂物面积测量的偏差、预剥蚀导致的夹杂物剥落等因素都会对夹杂物面积与信号强度之间的线性统计关系产生影响。     

高流速辉光放电质谱法测定纯镍中41种痕量元素

建立了高流速辉光放电质谱法（GDMS）测定纯镍中41种痕量元素含量的分析方法。使用有证标准物质IARM 190A校正其中29种元素的相对灵敏度因子（RSF）,其他12种元素采用标准RSF。在放电电流40 mA、放电电压1000 V、气体流速400 mL/min条件下,对样品预溅射20 min后进行测定。各元素的方法定量限在0.0000001%～0.000054%之间。应用该方法分析2个纯镍样品中的41种痕量元素,测定结果与高分辨电感耦合等离子体质谱法（HR-ICP-MS）、原子荧光光谱法（AFS）、高频感应炉燃烧红外吸收法测定结果一致,当待测元素含量大于0.0001%时,结果的相对标准偏差（RSD）为0.1%～13%;当待测元素含量在0.00001%～0.0001%之间时,测定结果的RSD为0.4%～46%;当待测元素含量小于0.00001%时,测定结果的RSD为7.4%～48%。     

原子簇正负离子的统计分布与生成机理

在分析了实验记录的大量原子簇离子质谱的基础上，发现原子簇的正负离子通常表现为不同的统计分布形式．将它们的分布形式与求解动力学方程得出的分布函数相比，发现由此反映了原子簇正负离子的不同的生成机理：实验所检测的原子簇正离子在许多情况下仅经历了聚合与解离反应，主要是中性原子簇分子电离后的产物；而相应的原子簇负离子则是经历了一系列离子一分子反应后的产物．     

毛细管区带电泳测定纳米粒子粒度分布的研究

建立了一种用毛细管区带电泳测定纳米粒子平均粒径及粒径分布的新方法。该方法通过外标定量法对样品的原始电泳谱图进行定量校正,从而得到样品的粒径分布图及平均粒径。外标定量法包括迁移时间-粒径校正曲线的建立及不同粒径含量校正曲线的建立。该方法所需样品量少,且粒度分布结果具有统计代表性。     

AB5型储氢合金的高倍率放电性能及机制

本文研究了储氢合金表面处理，粒度分布，稀土组成和添加剂硼对储氢合金高倍率放电性能的影响及机制的探讨。采用物理方法和化学方法对储氢合金进行表面处理，提高了合金表面电化学反应速度，同时促进了氢原子在合金本体中的扩散，从而改善了合金的活化性能、放电容量和高倍率放电能力。储氢合金粉粒度太粗和太细都使合金电极阻抗增大，导致放电容量和高保率放电能力下降，而且大电流放电平台也较低，选择合适的储氢合金粉粒度分布既可提高合金的活性和放电容量又能改善合金高倍率放电能力。随着合金中La含量的增加和Ce含量的减少，提高了合金的表面活性，使合金的大电流放电性能得到改善。储氢合金中加入元素B，使合金易粉化并形成少量的第二相，不但改善了合金的活性和放电容量而且显著地提高了合金高倍率放电能力。     

新一代有机电致发光材料突破激子统计

激子（或自旋）统计是基本的物理原理,决定有机半导体器件中形成单线态与三线态激子的比例（1：3）．近年来,基于新原理（三线态反系间窜越、延迟荧光）的OLED材料引起广泛关注．该类材料在理论方面重新催热了关于自旋统计的探讨,在应用方面有望发展成为低成本、高性能的新一代OLED材料,在国内相关领域得到重视,多个研究机构已布局开展相关研究．从目前的发展情况看,该类材料的发光机制、原理以及进一步材料设计思路还有待探讨和明确．鉴于此,本文综述了激子统计研究进展,分析了多种提高激子利用效率的途径,提出本课题组提高激子利用率的“热激子过程”新思路及杂化局域．电荷转移（HLCT）态材料设计原理,器件实现接近100％的激子利用效率．     

介质阻挡放电-发射光谱测定偏二甲肼

基于气相色谱分离、低温等离子放电与发射光谱技术建立了偏二甲肼（UDMH）的测定方法。以介质阻挡放电（DBD）低温等离子体作为偏二甲肼的发射光谱（OES）激发源、DBD-OES微型发射光谱系统产生的384.94 nm特征光谱为检测信号，电荷耦合检测器（CCD）采集信号。仪器检出限为0.48μg/L;UDMH质量浓度为5μg/L时，相对标准偏差（RSD）为1.3%；环境水样的加标回收率为84%～90%。方法可应用于痕量偏二甲肼的检测和应急监测。     

Original position statistic distribution analysis (original position analysis)——A new analytical method in research and quality evaluation of materials

The property of the material is closely related to its chemical compositions and microstruc-tures, which are the important parameters in the judgement of the quality of the material. The conventional chemical composition content of the material is an average value of the chemical composition of the whole material tested or the content of a fix position. Although it is still neces-sary to further improve these conventional methods, there are mature and systematic methods for analyzing the conve…     

Investigation of the analytical performance of gliding spark source mass spectrometry (GSSMS) for the trace analysis of nonconducting materials

A radiofrequency (rf) spark discharge in vacuum developing across the surface of dielectrics – a so-called gliding spark – has been applied to the direct mass spectrometric trace analysis of nonconducting materials. The special configuration of the electrodes strengthened the electric field over the surface of a nonconducting sample and created optimum conditions for the sputtering and ionization of the sample material. Mass spectrometric investigations of the charge composition of atomic ion and molecular ion formation in radiofrequency gliding spark plasma showed a significant difference to that of the original rf spark discharge between two conducting electrodes. The analytical figures of merit (reproducibility, relative sensitivity factors and detection limits of chemical elements) of gliding spark source mass spectrometry have been studied by using the glass standard reference materials NIST SRM 610 and 611 for the determination of trace elements in glass matrix.     

Investigation of the analytical performance of gliding spark source mass spectrometry (GSSMS) for the trace analysis of nonconducting materials

A radiofrequency (rf) spark discharge in vacuum developing across the surface of dielectrics – a so-called gliding spark – has been applied to the direct mass spectrometric trace analysis of nonconducting materials. The special configuration of the electrodes strengthened the electric field over the surface of a nonconducting sample and created optimum conditions for the sputtering and ionization of the sample material. Mass spectrometric investigations of the charge composition of atomic ion and molecular ion formation in radiofrequency gliding spark plasma showed a significant difference to that of the original rf spark discharge between two conducting electrodes. The analytical figures of merit (reproducibility, relative sensitivity factors and detection limits of chemical elements) of gliding spark source mass spectrometry have been studied by using the glass standard reference materials NIST SRM 610 and 611 for the determination of trace elements in glass matrix. Received: 31 March 1999 / Revised: 10 May 1999 / Accepted: 13 May 1999     

Effects of several experimental parameters on the relative sensitivity factors in spark-source mass spectrometric analysis of steel

The effects of spark gap, sample electrode size, spark technique, spark position, and energy-pass bandwidth of the ion beam, on the relative sensitivity factors in analysis for trace elements in steel by spark-source mass spectrometry have been investigated by means of electrical-detection, peak-switching techniques. The effects of spark gap and spark position are of the greatest importance. The energy distributions of both matrix and impurity ions were measured. For several elements, changes in spark position produced corresponding changes in the distribution of ion energies. These changes of energy distribution were partly responsible for variations in relative sensitivity factors with changing spark position.     

Evaporation of material and influence of auxiliary spark gap on the spectral excitation by means of laser emission spectroscopy for local analysis of graphite

For the determination of impurities in graphite, laser-micro-emission spectroscopy allows the analysis of much smaller sample areas than possible by spectroscopic analysis of arc or spark discharges.Because the maximum quantity of material which can be evaporated by a laser beam is only approximately 8μg, it was found necessary to introduce a spark gap above the evaporation pit to provide additional excitation of the plasma, thereby increasing the sensitivity of the analysis. In this way, the radiation intensity of the plasma was increased by two orders of magnitude.The effects of the spark gap parameters, voltage, capacitance and inductance, on the spectral excitation were investigated. Voltage and capacitance determine the energy supplied to the spark gap, whereas capacitance, together with inductance, controls the duration and characteristic of the discharge. To obtain the optimum additional excitation, the duration of the spark discharge had to be matched with the time taken for the material to evaporate.The catalytic effect of some impurity elements on the corrosion of graphite was identified by using the technique to analyse material in the corrosion pits of irradiated graphite fuel elements.     

Analysis of semiconducting materials by high-resolution radiofrequency glow discharge mass spectrometry

The analytical capabilities of a high-resolution mass spectrometer in combination with a 13.56 MHz glow discharge ion source for the analysis of semiconducting materials (silicon carbide and gallium arsenide) were studied. It was shown that single positively charged ions of sample material have about 10 eV higher average energy than the ions of the discharge and residual gas. Therefore effective energy separation of the ions of analyte from the ions of the discharge and residual gas was achieved by adjusting the ion transfer optics (breadth and position of energy slit), which improves the analytical capabilities of the developed method.Some analytical applications are presented to illustrate the performance of r.f. GDMS for the bulk analysis of semiconducting materials. The results of the trace element analysis of gallium arsenide and silicon carbide samples are compared with data of independent methods (LIMS, ICP-AES, SIMS).Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthdayOn leave from the Institute of Inorganic Chemistry, 630090 Novosibirsk, Russia     

Einfluß des Gefüges und der Entladungsgase bei der Spektralanalyse von Al-Legierungen

Studies of the spectrochemical behaviour of aluminium alloys subjected to spark discharge at high or medium frequency demonstrate how particularly type and concentration of the alloying element, the discharge gas and structure of the alloy are bearing down on the shape of the analytical curve and influence the quantitative analysis. Changes in the microstructure of Al-alloys, discovered both after spark and general treatment of the samples, shift the analytical curve markedly whenever Cu, Mg or Zn is the alloying element. Spark generating in different ambient gases yields similar effects. Heat developing during spark discharge initiates surface melting on the electrodes with the consequence of metallurgical changes in the original alloy. Proof was given by microprobe analysis that a sample becomes homogeneous in the course of this secondary localized melting process. Depth and nature of the affected zone is solely given by the ambient gas during discharge, if all the other parameters during spark generation are kept constant. The study demonstrates the influence of (A) the thermo-chemical behaviour of the aluminium alloys and (B) of the physical properties of the alloying elements under investigation on the spectroanalytical results.     

Sliding spark spectroscopy — a new excitation source for generating atomic emission spectra for analysis

In this paper a newly developed technique, the so-called “Sliding Spark Spectrometry” is described. The method, with a comparatively simple system, allows direct in-situ analysis of handy, compact non-conductive material without prior sample preparation. A new excitation source for optical emission spectroscopy has been developed. The basic principle of the method is the thermal vaporization, ionization and excitation of a small amount of surface substrate using a train of high-current sliding sparks. The material components in the spark plasma are activated to emit radiation. From the atomic spectrum, informations about the composition and the element concentration in the sample can be obtained. With the use of the sliding spark spectrometer, a rapid analysis, especially of chlorine containing waste plastics and their inorganic additives can be carried out.     

Study of high-voltage breakdown and material consumption in spark-source mass spectrometry and their significance in analytical applications

The breakdown voltage has been found to be dependent on the gap width between the electrodes and on the melting point of the sample elements in spark-source mass-spectrometry (SSMS). The number of discharges per pulse train and the time required to reach the first discharge depend only on the chosen breakdown voltage. The spark gap is proportional to the "radius" of the volume sampled (for a given element) and this radius is linearly related to the reciprocal of the melting point of the elements (23 different elements, metals or semiconductors), when fixed spark-parameters are used. The effect of electrode temperature on material consumption can be qualitatively explained by a fictive increase or decrease in melting point of the element. Knowledge of the relations between the different spark and instrumental parameters and the volume or weight of sample consumed can be applied to the study of the homogeneity of samples, to in-depth analysis by SSMS and to the analysis of microsamples.