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11.
Extensive compositional heterogeneity is shown to affect at least twenty four of the doped trace elements in the NIST SRM 610-617 glasses.
Compositional profiling and mapping using laser ablation ICP-MS reveals that all NIST SRM 610-617 wafers examined here contain domains that are significantly depleted in Ag, As, Au, B, Bi, Cd, Cr, Cs, Mo, Pb, Re, (Rh), Sb, Se, Te, Tl and W, and antithetically enriched in Cu (and Pt), with large enrichments in Cd, Fe and Mn also being encountered in some cases. These domains are visible in doubly polished wafers by unaided visual inspection and by transmitted light and schlieren microscopy. They occur in close proximity to the wafer perimeters and also as stretched and complexly folded forms within wafer interiors. The chemical and optical properties of these heterogeneous domains are consistent with those of compositional cords, a phenomenon of glass manufacture where glass bulk composition and physical properties are modified by loss of volatile components from the molten glass surface. The NIST SRM 610-617 glasses may be considered reliable reference materials for microanalysis of only between one half and two thirds of the trace elements with which they were doped, including Be, Mg, Sr, Ba, Sc, Y, REE, V, Zr, Hf, Nb, Ta, Th, U, Ga, In, Sn, Co, Ni and Zn. These elements show no evidence of significant heterogeneity, indicating that the original glass constituents and possible residues remaining in the furnace from preceding glass batch fusions were well homogenised during manufacture. 相似文献
Compositional profiling and mapping using laser ablation ICP-MS reveals that all NIST SRM 610-617 wafers examined here contain domains that are significantly depleted in Ag, As, Au, B, Bi, Cd, Cr, Cs, Mo, Pb, Re, (Rh), Sb, Se, Te, Tl and W, and antithetically enriched in Cu (and Pt), with large enrichments in Cd, Fe and Mn also being encountered in some cases. These domains are visible in doubly polished wafers by unaided visual inspection and by transmitted light and schlieren microscopy. They occur in close proximity to the wafer perimeters and also as stretched and complexly folded forms within wafer interiors. The chemical and optical properties of these heterogeneous domains are consistent with those of compositional cords, a phenomenon of glass manufacture where glass bulk composition and physical properties are modified by loss of volatile components from the molten glass surface. The NIST SRM 610-617 glasses may be considered reliable reference materials for microanalysis of only between one half and two thirds of the trace elements with which they were doped, including Be, Mg, Sr, Ba, Sc, Y, REE, V, Zr, Hf, Nb, Ta, Th, U, Ga, In, Sn, Co, Ni and Zn. These elements show no evidence of significant heterogeneity, indicating that the original glass constituents and possible residues remaining in the furnace from preceding glass batch fusions were well homogenised during manufacture. 相似文献
12.
Zhaochu Hu Shan Gao Yongsheng Liu Juan Xu Shenghong Hu Haihong Chen 《Geostandards and Geoanalytical Research》2008,32(3):347-360
Niobium and Ta concentrations in MPI‐DING and USGS (BCR‐2G, BHVO‐2G, BIR‐1G) silicate rock glasses and the NIST SRM 610–614 synthetic soda‐lime glasses were determined by 193 nm ArF excimer laser ablation and quadrupole ICP‐MS. Measured Nb and Ta values of MPI‐DING glasses were found to be consistently lower than the recommended values by about 15% and 25%, respectively, if calibration was undertaken using commonly accepted values of NIST SRM 610 given by Pearce et al. Analytical precision, as given by the 1 s relative standard deviation (% RSD) was less than 10% for Nb and Ta at concentrations higher than 0.1 μg g?1. A significant negative correlation was found between logarithmic concentration and logarithmic RSD, with correlation coefficients of ‐0.94 for Nb and ‐0.96 for Ta. This trend indicates that the analytical precision follows counting statistics and thus most of the measurement uncertainty was analytical in origin and not due to chemical heterogeneities. Large differences between measured and expected Nb and Ta in glasses GOR128‐G and GOR132‐G are likely to have been caused by the high RSDs associated with their very low concentrations. However, this cannot explain the large differences between measured and expected Nb and Ta in other MPI‐DING glasses, since the differences are normally higher than RSD by a factor of 3. Count rates for Nb and Ta, normalised to Ca sensitivity, for the MPI‐DING, USGS and NIST SRM 612–614 glasses were used to construct calibration curves for determining NIST SRM 610 concentrations at crater diameters ranging from 16 (im to 60 μm. The excellent correlation between the Nb/Ca1μgg‐1 signal (Nb represents the Nb signal intensity; Ca1μg g‐1 represents the Ca sensitivity) and Nb concentration, and between the Ta/Ca1μg g‐1 signal (where Ta represents the Ta signal intensity; Ca1μg g‐1 represents the Ca sensitivity) and Ta concentration (R2= 0.9992–1.00) in the various glass matrices suggests that matrix‐dependent fractionation for Nb, Ta and Ca was insignificant under the given instrumental conditions. The results confirm that calibration reference values of Nb and Ta in NIST SRM 610 given by Pearce et al. are about 16% and 28% lower, respectively. We thus propose a revision of the preferred value for Nb from 419.4 ± 57.6 μg g?1 to 485 ± 5 μg g?1 (1 s) and for Ta from 376.6 ± 77.6 μg g?1 to 482 ± 4 μg g?1 (Is) in NIST SRM 610. Using these revised values for external calibration, most of the determined average values of MPI‐DING, USGS and NIST SRM 612–614 reference glasses agree within 3% with the calculated means of reported reference values. Bulk analysis of NIST SRM 610 by standard additions using membrane desolvation ICP‐MS gave Nb = 479 ± 6 μg g?1 (1 s) and Ta = 468 ± 7 μg g?1 (1 s), which agree with the above revised values within 3%. 相似文献
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14.
D. P. Zarubin 《Physics and Chemistry of Minerals》2000,27(8):590-597
Simple model calculations show that the reversible temperature effects reported for broad OH-stretching bands in infrared
spectra of silica, aluminosilicate, and similar glasses can be explained, in essentials, by homogeneous thermal broadening
of the ν(OH) envelope constituents and a decrease in intensity with increasing temperature taking place uniformly across the
band. This means that these effects are reasonably consistent with the temperature behaviour of narrow ν(OH) bands of crystalline
OH-bearing minerals. These findings leave little room for the previously agreed interpretation in terms of a change in hydrogen-bonding
strength, although the dependence of integrated intensity on temperature still remains to be understood.
Received: 16 April 1999 / Accepted: 4 April 2000 相似文献
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16.
Qi‐Chao Yang Klaus Peter Jochum Brigitte Stoll Ulrike Weis Dmitry Kuzmin Michael Wiedenbeck Heike Traub Meinrat O. Andreae 《Geostandards and Geoanalytical Research》2012,36(3):301-313
To test whether the silicate reference glasses BAM‐S005‐A and BAM‐S005‐B from BAM (The Federal Institute for Materials Research and Testing, Germany) are suitable materials for microanalysis, we investigated the homogeneity of these reference glasses using the microanalytical techniques EPMA, LA‐ICP‐MS and SIMS. Our study indicated that all major and most trace elements are homogeneously distributed at micrometre sampling scale in both types of glass. However, some trace elements (e.g., Cs, Cl, Cr, Mo and Ni) seem to be inhomogeneously distributed. We also determined the composition of BAM‐S005‐A and BAM‐S005‐B. The EPMA data of major elements confirmed the information values specified by the certificate. With the exception of Sr, Ba, Ce and Pb, our trace element data by LA‐ICP‐MS were also in agreement with the certified values within the stated uncertainty limits. The reasons for the discrepancy in these four elements are still unclear. In addition, we report new data for twenty‐two further trace elements, for which the concentrations were not certified. Based on our investigation, we suggest that both of these materials are suitable for many microanalytical applications. 相似文献
17.
《Chemie der Erde / Geochemistry》2019,79(1):1-61
The Earth’s impact record is known to be rather limited in both time and space. There are ca. 190 impact structures currently known on Earth, representing a minor fraction of all the impact events that contributed to the initial formation of our protoplanet, and then to formation and modification of the surface of the planet. Moreover, the distribution of impact structures on Earth is manifestly uneven. One continent that stands out for its relatively small number of confirmed impact structures and impact ejecta occurrences is South America. The limited impact record for this large continent makes a robust case that there is a significant potential for further discoveries. Significant information on the impact record of South America is dispersed in different types of publications (journal articles, books, conferences abstracts, etc.), and in several languages, making it difficult to access and disseminate it among the geoscientific community. We aim to present a summary of the current knowledge of the impact record of this continent, encompassing the existing literature on the subject. It is published in two parts, with the first one covering an up-to-date introduction to impact cratering processes and to the criteria to identify/confirm an impact structure and related deposits. This is followed by a comprehensive analysis of the Brazilian impact structures. The Brazilian impact record accounts for the totality of the large structures of this kind currently confirmed in South America. The second part will examine the impact record of other countries in South America, provide information about a number of proposed impact structures, and review those that already have been discarded as not being formed by impact. 相似文献
18.
W R Taylor 《Journal of Earth System Science》1990,99(1):99-117
Infrared (IR) and Raman spectroscopic methods are important complementary techniques in structural studies of aluminosilicate glasses. Both techniques are sensitive to small-scale (<15 Å) structural features that amount to units of several SiO4 tetrahedra. Application of IR spectroscopy has, however, been limited by the more complex nature of the IR spectrum compared with the Raman spectrum, particularly at higher frequencies (1200–800 cm?1) where strong antisymmetric Si-O and Si-O-Si absorptions predominate in the former. At lower frequencies, IR spectra contain bands that have substantial contributions from ‘cage-like’ motions of cations in their oxygen co-ordination polyhedra. In aluminosilicates these bands can provide information on the structural environment of Al that is not obtainable directly from Raman studies. A middle frequency envelope centred near 700 cm?1 is indicative of network-substituted AlO4 polyhedra in glasses with Al/(Al+Si)>0·25 and a band at 520–620cm?1 is shown to be associated with AlO6 polyhedra in both crystals and glasses. The IR spectra of melilite and melilite-analogue glasses and crystals show various degrees of band localization that correlate with the extent of Al, Si tetrahedral site ordering. An important conclusion is that differences in Al, Si ordering may lead to very different vibrational spectra in crystals and glasses of otherwise gross chemical similarity. 相似文献
19.
Marghaleray Amini Anton Eisenhauer Florian Böhm Chris Holmden Katharina Kreissig Folkmar Hauff Klaus Peter Jochum 《Geostandards and Geoanalytical Research》2009,33(2):231-247
We report δ44/40Ca(SRM 915a) values for eight fused MPI‐DING glasses and the respective original powders, six USGS igneous rock reference materials, the U‐Th disequilibria reference material TML, IAEA‐CO1 (Carrara marble) and several igneous rocks (komatiites and carbonatites). Sample selection was guided by three considerations: (1) to address the need for information values on reference materials that are widely available in support of interlaboratory comparison studies; (2) support the development of in situ laser ablation and ion microprobe techniques, which require isotopically homogenous reference samples for ablation; and (3) provide Ca isotope values on a wider range of igneous and metamorphic rock types than is currently available in the scientific literature. Calcium isotope ratios were measured by thermal ionisation mass spectrometry in two laboratories (IFM‐GEOMAR and Saskatchewan Isotope Laboratory) using 43Ca/48Ca‐ and 42Ca/43Ca‐double spike techniques and reported relative to the calcium carbonate reference material NIST SRM 915a. The measurement uncertainty in both laboratories was better than 0.2‰ at the 95% confidence level. The impact of different preparation methods on the δ44/40Ca(SRM 915a) values was found to be negligible. Except for ML3‐B, the original powders and the respective MPI‐DING glasses showed identical δ44/40Ca(SRM 915a) values; therefore, possible variations in the Ca isotope compositions resulting from the fusion process are excluded. Individual analyses of different glass fragments indicated that the glasses are well homogenised on the mm scale with respect to Ca. The range of δ44/40Ca(SRM 915a) values in the igneous rocks studied was larger than previously observed, mostly owing to the inclusion of ultramafic rocks from ophiolite sections. In particular, the dunite DTS‐1 (1.49 ± 0.06‰) and the peridotite PCC‐1 (1.14 ± 0.07‰) are enriched in 44Ca relative to volcanic rocks (0.8 ± 0.1‰). The Carrara marble (1.32 ± 0.06‰) was also found to be enriched in 44Ca relative to the values of assumed precursor carbonates (< 0.8‰). These findings suggest that the isotopes of Ca are susceptible to fractionation at high temperatures by, as yet, unidentified igneous and metamorphic processes. 相似文献
20.
矿物和玻璃中NaK—边的同步辐射XANES研究 总被引：2，自引：0，他引：2
本文利用同步辐射的NaK-边X射线近边结构谱（XANES）研究了含Na矿物NaK-边的特征谱，其谱的能量位置随着配位数垢增加而增大，同时建立了含磷（P）的钠玻璃中NaK-边的能量，随着P的含量增加而增大，由此表明本方法可以作为研究含Na矿物和Na玻璃的配位与局部结构的新方法。 相似文献