Determination of Y, Zr and ultra-low Nb concentrations in geological material by multi-ion counting spark-source mass spectrometry (MIC-SSMS)

Precise concentrations of Zr, Y and Nb in the μg/g to ng/g range have been determined in rock samples using multi-ion counting spark-source mass spectrometry (MIC-SSMS). A high resolution method, combined with interference correction on ⁹¹Zr and ⁹³Nb for low concentration samples, was applied. An analytical precision of 2–5% for concentrations down to 0.020 μg/g and 10% for lower concentrations was attained. The detection limit is below 0.005 μg/g. By measuring international reference materials, the accuracy of the method was determined to be within about 10% of the recommended values. However, the accuracy of the final concentration is influenced by interference corrections, but the additional error is below 20%. The interference problem is most difficult for Al-rich samples (>15% Al₂O₃), as the interfering molecules are ⁴⁰Ca²⁷Al¹²C₂ ⁺ and ²⁷Al₃ ¹²C⁺. The accordance between ICP-MS and MIC-SSMS results is worse for low Nb concentrations in the ng/g range. Here, ICP-MS gives systematically lower values than MIC-SSMS. The reason for this discrepancy is not yet clear, but may be caused by Nb loss during chemical treatment of the samples prior to ICP-MS measurements. Received: 29 December 1998 / Revised: 19 April 1999 / Accepted: 21 April 1999     

Determination of Y, Zr and ultra-low Nb concentrations in geological material by multi-ion counting spark-source mass spectrometry (MIC-SSMS)

Precise concentrations of Zr, Y and Nb in the μg/g to ng/g range have been determined in rock samples using multi-ion counting spark-source mass spectrometry (MIC-SSMS). A high resolution method, combined with interference correction on ⁹¹Zr and ⁹³Nb for low concentration samples, was applied. An analytical precision of 2–5% for concentrations down to 0.020 μg/g and 10% for lower concentrations was attained. The detection limit is below 0.005 μg/g. By measuring international reference materials, the accuracy of the method was determined to be within about 10% of the recommended values. However, the accuracy of the final concentration is influenced by interference corrections, but the additional error is below 20%. The interference problem is most difficult for Al-rich samples (>15% Al₂O₃), as the interfering molecules are ⁴⁰Ca²⁷Al¹²C₂ ⁺ and ²⁷Al₃ ¹²C⁺. The accordance between ICP-MS and MIC-SSMS results is worse for low Nb concentrations in the ng/g range. Here, ICP-MS gives systematically lower values than MIC-SSMS. The reason for this discrepancy is not yet clear, but may be caused by Nb loss during chemical treatment of the samples prior to ICP-MS measurements.     

Synthesis and structures of some heterometallic [(Li, Y)2, (M3, Ce) (M = Li or Na), (Li, Zr2) and (Li, Zr)4] oligomeric diamides derived from 1,2-bis(neopentylamino)benzene

The following crystalline, X-ray-characterised heterometallic oligomeric diamides have been prepared in good yield under mild conditions in diethyl ether from the dilithio or disodio derivative of the N,N'-dineopentyl-1,2-diaminobenzene [{N(H)(CH2Bu(t))}2C6H4-1,2] (abbreviated as H2L):[Y(L)(mu-Cl)2Li(OEt2)2]2 (1), [Li(OEt2)2Li(mu2-Cl)4(mu3-Cl)2{Zr(L)}2]2 (2), [Zr(L)2(mu-Cl){Li(OEt2)2}(mu2-Cl)2Zr(L)] (3), [Ce{(mu-L)M}3(OEt2)(1/2)] (3M = Li(1.82)Na(1.18)) (4), [Ce{(mu-L)Na}3(OEt2)] (5) and [Ce{(mu-L)Na}3] (6). Compounds 1-3 were obtained from Li2(L) and YCl3 (the colourless 1) or ZrCl4 (the red 2 and 3), while the red 4 and 5 were isolated from CeCl3 and M2(L) (3M = Li(1.82)Na(1.18)) (4) or Na2(L) (5). Attempted oxidation of 5 with Br2 in hexane yielded the black 6. The ligand is N,N'-chelating to each of the d- or f-block metals in 1-6; and in 4-6 L is also acting as a bridge between Ce and the alkali metal, to which L is thus also chelating.     

Si drift detector in comparison to Si(Li) detector for total reflection X-ray fluorescence analysis applications

TXRF is routinely used and suited to inspect Si wafer surfaces for possible impurities of metallic elements at the level of pg and below. Lightweight, compact sized, high-resolution Silicon drift detectors (FWHM=148 eV at 5.9 keV) electically cooled and with high throughput are ideally as the new spectrometer and for clean room application. A KETEK 5 mm² Si drift detector was compared with a NORAN 80 mm² SiLi in a previously commercially available ATOMIKA 8010 wafer analyzer. Results are presented and show that almost the same detection limits for both detector types were achieved analyzing a droplet sample containing 1 ng Ni on a Si wafer. Also, the performance to detect low Z elements like Na, excited with monochromatic Cr K radiation in a vacuum chamber was tested and detection limits of 600 pg obtained.     

Quantitative analysis of elements (C, N, O, Al, Si and Fe) in polyamide with wavelength dispersive X-ray fluorescence spectrometry

A wavelength dispersive X-ray fluorescence (WD-XRF) spectrometry combined with calibration curve method was established for simultaneously analyzing low-Z elements (C,N,O) and Al,Si,Fe in polyamide.To investigate the origin of plastic material causing deposition and blocking in instrument engines and pipelines,polyamide 6 (PA 6,an engineering plastic) was chosen as the study object on account of its common use in industry.The sample preparation with pressed powder disk has been developed for determination of six elements in PA 6.Pure Cu metal was used as the matrix and PA 6 was regarded as standard sample for C,N,O elements.PA 6 particles were firstly smashed to uniform powder in liquid nitrogen,and then mixed with inorganic standard powders (Fe2O3,Al2O3,SiO2,and Na 2 SiO 3).The mixture was ground to obtain homogeneous calibration materials for WD-XRF analysis.The quantitative property of the calibration curve method for each element was reliable.The limits of detection (S/N≤3) of C,N,O,Al,Si and Fe using WD-XRF were 249,120,101,6.2,3.3,and 1.8 μg/g,respectively.To confirm the accuracy of the proposed WD-XRF calibration curve method,inductively coupled plasma optical emission spectroscopy (ICP-OES) detection for Al,Si,Fe and elemental analyzer (EA) analysis for C,N,O were utilized.A good correlation of the WD-XRF results with the measurements of ICP-OES and EA was observed.     

Agostic interaction in the methylidene metal dihydride complexes H2MCH2 (M=Y, Zr, Nb, Mo, Ru, Th, or U)

Multiconfigurational quantum chemical methods (complete active space self-consistent field (CASSCF)/second-order perturbation theory (CASPT2)) have been used to study the agostic interaction between the metal atom and H(C) in the methylidene metal dihydride complexes H2MCH2, where M is a second row transition metal or the actinide atoms Th or U. The geometry of some of these complexes is highly irregular due to the formation of a three center bond CH...M, where the electrons in the CH bond are delocalized onto empty or half empty orbitals of d- or f-type on the metal. No agostic interaction is expected when M=Y, where only a single bond with methylene can be formed, or when M=Ru, because of the lack of empty electron accepting metal valence orbitals. The largest agostic interaction is found in the Zr and U complexes.     

A comparative study using liquid scintillation counting and X-ray spectrometry to determine 55Fe in radioactive wastes

The radionuclide ⁵⁵Fe was determined in samples of radioactive wastes from the water cleanup system of the IEA-R1 nuclear research reactor. In order to validate the results, the ⁵⁵Fe activity concentration was measured in eight waste samples and in six simulated samples containing the most important interfering radionuclides. A simple method was employed to separate and purify ⁵⁵Fe from other radionuclides present in these samples, combining co-precipitation with ammonium hydroxide and purification with anionic ion-exchange resin, which enables ⁵⁵Fe to be quantified either by liquid scintillation counting (LSC) or by X-ray spectrometry using a low-energy germanium spectrometer (LEGe). Both measurement methods were used so that the separation and purification process could be confirmed by comparison of spectra with and without the utilization of anionic ion-exchange resin. Activity and interferences were compared in the results obtained from LSC and LEGe measurement methods.     

Gas-phase conversion of the U(VI), Sr,Mo, and Zr compounds in nitrating atmosphere

The gas-phase conversion of U₃O₈, MoO₃, SrO, and their mechanical mixtures, and also of ZrO₂ into water-soluble compounds in the atmosphere of (NO _x  + vapor H₂O) or HNO₃ (vapor) was studied. In the course of gas-phase conversion, U₃O₈ and SrO transform into water-soluble compounds (nitrates, hydroxonitrates), whereas MoO₃ and ZrO₂ undergo no changes. The principal possibility of separating U from Mo and Zr by gas-phase conversion of the oxides in the atmosphere of (NO _x  + vapor H₂O) or HNO₃ (vapor) was demonstrated.     

Determination of Sr,Zn, Cu and Fe in Licorice by X-ray Fluorescence Spectrometry

Few persons determine the trace elements in the licorice by X-ray fluorescence spectrometry (XRF), because there is no standard samples of the licorice. This paper describes the method to determine Sr,Zn,Cu and Fe in licorice using XRF. The samples are ashed and then determined with the powder process. The measured results are corrected by artificial standard samples.     

Determination of Fe, Nb and Si in titanium (IV) oxide white pigments by AAS using multivariate linear calibration methods

Models for the quantitative determination of Fe, Nb and Si in titanium (IV) oxide white pigments by flame atomic absorption spectrometry (AAS) are described. For the models two multivariate linear calibration techniques have been used: principal component regression (PCR) and partial least squares (PLS1). Absorbances measured at wavelengths for elements present in solution have been considered as independent (x) variables, while the concentrations of elements (or their oxide) to be determined have been taken as dependent (y) variables. The results obtained by the models do not differ significantly (=0.05) from those achieved by the XRF method checked in advance by another independent method, the neutron activation analysis (NAA).     

Determination of Fe,Nb and Si in titanium (IV) oxide white pigments by AAS using multivariate linear calibration methods

Models for the quantitative determination of Fe, Nb and Si in titanium (IV) oxide white pigments by flame atomic absorption spectrometry (AAS) are described. For the models two multivariate linear calibration techniques have been used: principal component regression (PCR) and partial least squares (PLS1). Absorbances measured at wavelengths for elements present in solution have been considered as independent (x) variables, while the concentrations of elements (or their oxide) to be determined have been taken as dependent (y) variables. The results obtained by the models do not differ significantly (alpha=0.05) from those achieved by the XRF method checked in advance by another independent method, the neutron activation analysis (NAA).     

A three-dimensional extended Sb network in the metallic antimonides (M',Ti)5Sb8 (M' = Zr, Hf, Nb, Mo)

(M',Ti)5Sb8 was prepared from the melt by arc-melting suitable mixtures of Ti, TiSb2, and M'Sb2, respectively. This phase exists at least with M' = Zr, Hf, Nb, and Mo. A significant phase range for Zr delta Ti5 - delta Sb8 was found to be within 1.10(8) < or = delta < or = 3.9(3). All (M',Ti)5Sb8 representatives investigated occur in the same, yet hitherto unknown structure type, as determined by single-crystal analyses. E.g., the lattice dimensions of Zr delta Ti5 - delta Sb8 range from a = 654.49(3) pm, c = 2662.4(2) pm for delta = 1.10(8) to a = 671.06(6), c = 2679.7(4) pm for delta = 3.9(3) (space group I4(1)22, No. 98, Z = 4). The three chemically inequivalent metal sites are statistically occupied by different mixtures of the M atoms M' and Ti, included in a three-dimensional network of Sb atoms on 6- to 8-fold Sb coordinated positions. Sb-Sb bonds of intermediate lengths occur in addition to the predominating heteronuclear M-Sb bonds. Physical property measurements of (Zr,Ti)5Sb8 reveal these phases being metallic exhibiting specific resistances of several m omega.cm and a small Seebeck coefficient at room temperature, in agreement with the results of the electronic structure calculations on the LMTO and extended Hückel levels. The calculations indicate a possible change to semiconducting properties by heavy doping.     

微波消解-电感耦合等离子体质谱（ICP-MS）法测定稀有多金属矿中锂铍铌钽铷铯

稀有多金属矿中的锂、铍、铌、钽、铷、铯6种元素经常伴生共存,铍的矿物大多难以被酸彻底溶解,铌、钽极易水解,准确测定这些元素需要多种方法,分析过程繁琐。本文建立了以电感耦合等离子体质谱（ICP-MS）法同时测定稀有多金属矿中锂、铍、铌、钽、铷、铯的方法。称取矿石样品放入高压罐中,加入氢氟酸+硫酸+硝酸的混酸,拧紧盖子后进行微波消解,在高温高压的作用下可使样品完全溶解;消解后的样品转移到聚四氟乙烯烧杯中,用电热板赶酸,以盐酸（50 %）提取样品,再加入3滴氢氟代替常规的酒石酸抑制铌、钽的水解,定容后用ICP-MS直接测定。考察了微波消解到温后的保持时间,结果表明30 min可将样品完全溶解;考察了提取液的用量,结果表明10 mL盐酸（50%）和3滴氢氟酸可将样品完全提取;优化了仪器测试条件、选择了合适的测定同位素和内标元素,各元素的质谱信号在0～20 μg/mL浓度范围呈良好的线性关系,相关系数（r）均在0.9999以上。使用微波消解法和电热板消解法分别对6个稀有多金属矿石国家一级标准物质分别进行溶解,结果表明电热板消解法铍的测定结果明显偏低,微波消解法各元素测定结果均在认定值的误差范围内。方法检出限值为3.0～10.0 μg /g;测试范围为0.001～4.3 %;相对标准偏差RSD（n=12）为0.32 ～12.5 %。质量参数满足地质矿产实验规范要求。     

Si X-ray absorption near edge structure (XANES) of Si,SiC, SiO2, and Si3N4 measured by an electron probe X-ray microanalyzer (EPMA)

Silicon K X-ray emission spectra of Si, SiC, Si₃N₄, and SiO₂ are measured using a wavelength dispersive electron probe X-ray microanalyzer. It is shown that the fine structures in the line shape of the low energy tail of the Kα characteristic X-ray emission spectra resemble those of the K X-ray absorption near edge structure (XANES). XANES spectra of 1 μm² area can be obtained by this method.     

ICP-AES法测定稀土镁合金(ZM6)中钕、锌、锆、铁、硅元素

介绍了用ICP-AES法分析稀土镁合金(ZM6)中钕、锆等五元素．通过对分析务件的选择，排除了基体镁和共存元素的干扰，确定了分析方法，用该方法分析五元素快捷、简便、准确度扣精密度较好。     

Unprecedented association of [Mo6Br(i) 7Y(i)Br(a) 6]3- cluster units and [Mo(III)Br6]3- complexes: synthesis, crystal structures, and properties of the double salts Rb3[Mo6Br(i) 7Y(i)Br(a) 6](Rb3[MoBr6])3 (Y=Se, Te)

The double salts Rb(3)[Mo(6)Br(i) (7)Y(i)Br(a) (6)](Rb(3)[MoBr(6)])(3) (Y=Se, Te) result from the partial disproportionation of the Mo(6)Br(12) octahedral-cluster-based bromide, in the presence of corresponding chalcogenides and RbBr salt (crystal data: Rb(12)[MoBr(6)](3)[Mo(6)Br(i) (7)Te(i)Br(a) (6)] (1), Pm$\bar 3$m (No. 221), a=12.1558(2) A, Z=1, R(1)=0.028; wR(2)=0.050; Rb(12)[MoBr(6)](3)[Mo(6)Br(i) (7)Se(i)Br(a) (6)] (2), Pm$\bar 3$m, a=12.144(3) A, Z=1, R(1)=0.028; wR(2)=0.050). The structures of 1 and 2 are built up from [Mo(III)Br(6)](3-) complexes and [Mo(6)Br(i) (7)Y(i)Br(a) (6)](3-) cluster units characterised by a random distribution of seven bromine and one chalcogen ligands on all the eight inner positions that face cap the Mo(6) clusters. Such a distribution implies a static orientational disorder of the [Mo(6)Br(i) (7)Y(i)Br(a) (6)](3-) units around the origin of the unit cell. Close-packed anionic layers based on [Mo(III)Br(6)](3-) complexes and [Mo(6)Br(i) (7)Y(i)Br(a) (6)](3-) cluster units are stacked in the sequence ABC. This arrangement leads to very short Br(a)--Br(a) intercluster unit distances of 3.252 A, much lower than the sum of the van der Waals radii (3.70 A). The trivalent oxidation state of molybdenum in the Mo complexes and 24 valence electrons per Mo(6) cluster have been confirmed by magnetic susceptibility measurements. Salts 1 and 2 constitute the first examples of structurally characterised bromides containing discrete [Mo(III)Br(6)](3-) complexes obtained by means of solid-state synthesis.     

Qualitative Analyses of Coins by Using a Si(Li) Detector and An Xrf-Exciter System

X-ray fluorescence spectra of many coins are studied using a Si(Li) detector and an XRF-exciter system. Some qualitative and semiquantitative analyses have been carried out. It is demonstrated that this method can be a very powerful means to study the archaeology of metal objects, especially the copper alloys, such as coins and bronze vessels.     

X射线荧光光谱法测定电解锰中锰、硅、磷和铁含量

熔融制样X射线荧光光谱法测定电解锰中锰、硅、磷和铁含量。用熔融后的四硼酸锂制作铂金坩埚保护层,以BaO2做氧化剂,在马弗炉内通过逐渐升温来氧化电解锰,然后熔融制取玻璃熔片,用X射线荧光(XRF)光谱法分析电解锰中锰、硅、磷和铁含量。锰、硅、磷和铁的相对标准偏差RSD分别为0.23%、2.82%、0.31%和0.53%。与其它分析方法比较,其结果更稳定。有效消除了电解锰熔融制样过程中的坩埚腐蚀问题,分析误差可完全控制在国家相关标准允许的范围内,实现了电解锰中各元素的快速准确测定。     

Stoichiometry determination of (Pb,La)(Zr,Ti)O3-type nano-crystalline ferroelectric ceramics by wavelength-dispersive X-ray fluorescence spectrometry

Analysis of small samples of lanthanum-doped lead zirconate titanate (PLZT) by wavelength-dispersive X-ray fluorescence spectrometry (WDXRF) is presented. The powdered material in ca. 30 mg was suspended in water and collected on the membrane filter. The pure oxide standards (PbO, La₂O₃, ZrO₂ and TiO₂) were used for calibration. The matrix effects were corrected using a theoretical influence coefficients algorithm for intermediate-thickness specimens. The results from XRF method were compared with the results from the inductively coupled plasma optical emission spectrometry (ICP-OES). Agreement between XRF and ICP-OES analysis was satisfactory and indicates the usefulness of XRF method for stoichiometry determination of PLZT.     

XPS and AES analysis of passive films on Fe-25Cr-X (X = Mo,V, Si and Nb) model alloys

Corrosion resistance of stainless steel is due to the presence of a thin passive film of typically 1-2 nm thickness. The influence of ternary alloying elements on the composition of passive films on Fe-Cr alloys and their pitting corrosion resistance has been investigated. Iron-chromium alloys were analyzed by XPS and AES with model alloys (Fe-25Cr-X with X = at % Mo, Si, V and Nb) formed in sulphate solution in the presence and absence of chloride ions. All ternary alloying elements increase the pitting potential compared to the corresponding binary alloy. Films formed in chloride containing sulphate solution contain both electrolyte anions. Scanning Auger microscopy reveals that for a two phase system such as Fe-25Cr-11Nb, the dendritic phase is enriched with chromium, while essentially all of the niobium is located in the interdendritic eutectic.