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Glass Samples (glass + sample)

Distribution by Scientific Domains

Chemistry	46%
Polymers and Materials Science	23%
Physics and Astronomy	15%

Selected Abstracts

Mechanical properties of single crystalline and glassy lithium triborate

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2008
I. P. Shakhverdova
Abstract Mechanical properties of LiB3O5 single crystal plates with different orientation as well as of glass with the same composition have been investigated. The nano- (H) and microhardness (HM), the reduced Young's modulus (Er) and the crack behaviour of the samples were studied. Both hardness and Young's modulus of glass appeared smaller in comparison to corresponding single crystal data (H , 7 , 8 GPa, HM , 6 GPa, Er , 70 , 80 GPa for glass and H , 10 , 15 GPa, HM , 6 ,11 GPa, Er , 93 , 155 GPa for single crystal). H, Er, and the plane of crack propagation proved orientation-dependent. Cracks in the glass sample were not observed up to 0.49 N microindentation load, whereas for the single crystal the cracks appeared already at 0.098N. In single crystals the observed cleavage planes {211} and/or {412} are oriented nearly parallel to planes of B-O rings. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Synthesis, Characterization, and In Vitro Bioactivity of Sol-Gel-Derived Zn, Mg, and Zn-Mg Co-Doped Bioactive Glasses

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2010
M. Erol
Abstract Bioactive glasses in the systems CaO-SiO2 -P2O5 -ZnO, CaO-SiO2 -P2O5 -MgO, and CaO-SiO2 -P2O5 -MgO-ZnO were prepared and characterized. Bioactive glass powders were produced by the sol-gel method. The prepared bioactive glass powders were immersed in a simulated body fluid (SBF) for periods of up to 28,days at 310,K to investigate the bioactivity of the produced samples. Inductively coupled plasma (ICP) and ultraviolet (UV) spectroscopic techniques were used to detect changes in the SBF composition. X-Ray diffraction (XRD) was utilized to recognize and confirm the formation of a hydroxyapatite (HA) layer on the bioactive glass powders. Microstructural characterizations of the bioactive glass samples were investigated by scanning electron microscopy (SEM) techniques. Density, porosity, and surface area values of bioactive glass powders were also determined in order to characterize the textural properties of the samples. The results revealed the growth of an HA layer on the surface of the bioactive glass samples. MgO in the glass sample increases the rate of formation of an HA layer while ZnO in the glass slows it down. [source]

Plasmonic Enhancement or Energy Transfer?

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2009
Its Potential for Light-Emitting Devices, Lanthanide-Doped Silicate Glasses, On the Luminescence of Gold-, Silver-
Abstract With the technique of synchrotron X-ray activation, molecule-like, non-plasmonic gold and silver particles in soda-lime silicate glasses can be generated. The luminescence energy transfer between these species and lanthanide(III) ions is studied. As a result, a significant lanthanide luminescence enhancement by a factor of up to 250 under non-resonant UV excitation is observed. The absence of a distinct gold and silver plasmon resonance absorption, respectively, the missing nanoparticle signals in previous SAXS and TEM experiments, the unaltered luminescence lifetime of the lanthanide ions compared to the non-enhanced case, and an excitation maximum at 300,350,nm (equivalent to the absorption range of small noble metal particles) indicate unambiguously that the observed enhancement is due to a classical energy transfer between small noble metal particles and lanthanide ions, and not to a plasmonic field enhancement effect. It is proposed that very small, molecule-like noble metal particles (such as dimers, trimers, and tetramers) first absorb the excitation light, undergo a singlet-triplet intersystem crossing, and finally transfer the energy to an excited multiplet state of adjacent lanthanide(III) ions. X-ray lithographic microstructuring and excitation with a commercial UV LED show the potential of the activated glass samples as bright light-emitting devices with tunable emission colors. [source]

Composition-Induced Variations in SIMS Instrumental Mass Fractionation during Boron Isotope Ratio Measurements of Silicate Glasses

GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2008
Martin Rosner
isotopes du bore; SIMS; effet de matrice; matériaux vitreux de référence; fractionnement de masse instrumental An analytical artefact is reported here related to differences in instrumental mass fractionation between NIST SRM glasses and natural geological glasses during SIMS boron isotope determinations. The data presented demonstrated an average 3.4, difference between the NIST glasses and natural basaltic to rhyolitic glasses mainly in terms of their sputtering-induced fractionation of boron isotopes. As no matrix effect was found among basaltic to rhyolitic glasses, instrumental mass fractionation of most natural glass samples can be corrected by using appropriate glass reference materials. In order to confirm the existence of the compositionally induced variations in boron SIMS instrumental mass bias, the observed offset in SIMS instrumental mass bias has been independently reproduced in two laboratories and the phenomenon has been found to be stable over a period of more than one year. This study highlights the need for a close match between the chemical composition of the reference material and the samples being investigated. Nous montrons l'existence d'un artefact analytique reliéà différents fractionnements de masse instrumentaux, observés sur les verres NIST SRM et des verres naturels durant des mesures des isotopes de bore par SIMS. Les données montrent une différence d'environ 3.4, entre les verres NIST et les verres naturels, de composition variant de basaltique à rhyolitique, en termes de fractionnement des isotopes du bore principalement induit par le phénomène de dispersion. Comme aucun effet de matrice n'a été observé entre les verres basaltiques et les verres rhyolitiques, le fractionnement de masse instrumental de la plupart des verres naturels peut être corrigé en utilisant des verres de références appropriés. Dans le but de confirmer l'existence de biais de masse liéà la composition lors de mesure du bore par SIMS, nous avons reproduit indépendamment le décalage observé entre deux laboratoires et ce phénomène s'est révélé stable sur une période de plus d'un an. Cette étude met en lumière le besoin d'ajuster précisément les compositions chimiques des matériaux de référence et des échantillons à analyser. [source]

Non-parametric permutation test for the discrimination of float glass samples based on LIBS spectra

JOURNAL OF CHEMOMETRICS, Issue 6 2010
Erin McIntee
Abstract Laser-induced breakdown spectroscopy (LIBS) coupled with non-parametric permutation based hypothesis testing is demonstrated to have good performance in discriminating float glass samples. This type of pairwise sample comparison is important in manufacturing process quality control, forensic science and other applications where determination of a match probability between two samples is required. Analysis of the pairwise comparisons between multiple LIBS spectra from a single glass sample shows that some assumptions required by parametric methods may not hold in practice, motivating the adoption of a non-parametric permutation test. Without rigid distributional assumptions, the permutation test exhibits excellent discriminating power while holding the actual size of Type I error at the nominal level. Copyright © 2010 John Wiley & Sons, Ltd. [source]

A Two-Level Model for Evidence Evaluation in the Presence of Zeros,

JOURNAL OF FORENSIC SCIENCES, Issue 2 2010
Grzegorz Zadora Ph.D.
Abstract:, Likelihood ratios (LRs) provide a natural way of computing the value of evidence under competing propositions. We propose LR models for classification and comparison that extend the ideas of Aitken, Zadora, and Lucy and Aitken and Lucy to include consideration of zeros. Instead of substituting zeros by a small value, we view the presence of zeros as informative and model it using Bernoulli distributions. The proposed models are used for evaluation of forensic glass (comparison and classification problem) and paint data (comparison problem). Two hundred and sixty-four glass samples were analyzed by scanning electron microscopy, coupled with an energy dispersive X-ray spectrometer method and 36 acrylic topcoat paint samples by pyrolysis gas chromatography hyphened with mass spectrometer method. The proposed LR model gave very satisfactory results for the glass comparison problem and for most of the classification tasks for glass. Results of comparison of paints were also highly satisfactory, with only 3.0% false positive answers and 2.8% false negative answers. [source]

Use of highly energetic (116,keV) synchrotron radiation for X-ray fluorescence analysis of trace rare-earth and heavy elements

JOURNAL OF SYNCHROTRON RADIATION, Issue 4 2001
Izumi Nakai
This study has revealed the advantages of the use of 116,keV X-rays as an excitation source of X-ray fluorescence (XRF) analyses. This technique is suitable for nondestructive multielemental analyses of heavy elements such as rare-earth elements. The lowest MDL value evaluated for the bulk analysis of a JG-1 standard reference sample (granite rock) was 0.1 p.p.m. for W for a 500,s measurement. The spectrum of standard glass samples of SRM612 demonstrated clearly resolved K -line peaks of more than 30 elements, including all the existing rare-earth elements, at 50 p.p.m. levels. The calibration curve for the determination of a rare-earth element shows a linear relation between the XRF intensity and concentrations from 10 to 0.03,ng. This powerful technique should be useful for nondestructive analyses of rare-earth and heavy elements in geological, geochemical and archaeological samples as well as industrial materials. [source]

Role of Sulfate in Structural Modifications of Sodium Barium Borosilicate Glasses Developed for Nuclear Waste Immobilization

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2008
Raman K. Mishra
A sodium barium borosilicate glass matrix with a higher solubility of sulfate has been developed recently at Bhabha Atomic Research Centre for vitrification of sulfate bearing high-level nuclear waste. We report here the studies carried out to understand the influence of sulfate ion on the three-dimensional borosilicate network. Experiments were carried out with sodium barium borosilicate base glass samples loaded with varying amounts of SO42, (0,5 mol%). Phase separation studies on the samples revealed that as much as 3 mol% of SO42, can be loaded within the base glass without any phase separation, however, beyond this limit BaSO4 (barite) crystallizes within the matrix. Thermal analyses of the samples indicated a shift in glass transition temperature from 534° (0 mol% SO42,) to 495°C (3 mol% SO42,) and it remained more or less unaltered afterwards even with high SO42, loading. A similar observation of structure stabilization was obtained from 29Si MAS,NMR studies also, which showed that with 2 mol% of SO42, loading, the Q2:Q3 ratio changed from 59:41 (for samples with 0 mol% SO42, loading) to 62:38 and it remained almost the same afterwards even with higher SO42, loading. 11B MAS NMR patterns of the glass samples, however, remained unchanged with SO42, loading ([BO4]:[BO3]=38:62). Based on 29Si and 11B MAS NMR studies, the authors propose two different ways of interaction of SO42, ions with the borosilicate network: (i) the network modifying action of SO42, ions with -Si,O,Si- linkages, at low SO42, ion concentration (<2 mol%) and (ii) the preferential interaction of SO42, with the Ba2+ ions at high SO42, concentration (>2 mol%). [source]

Study of Mn2+ luminescence in Zn(PO3)2 glasses

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2007
M. C. Flores J.
Abstract The optical properties of Mn2+ doped Zn(PO3)2 glass are discussed. Depending on the manganese concentration in the glass samples, the Mn2+ emission band appears in the wavelength range from 515 to 620 nm. This behavior depends on the possible coordination number, a result confirmed by different lifetimes and also different structure of the absorption spectra. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

DEEPLY COLOURED AND BLACK GLASS IN THE NORTHERN PROVINCES OF THE ROMAN EMPIRE: DIFFERENCES AND SIMILARITIES IN CHEMICAL COMPOSITION BEFORE AND AFTER ad 150*

ARCHAEOMETRY, Issue 5 2009
V. VAN DER LINDEN
In this work we attempt to elucidate the chronological and geographical origin of deeply coloured and black glass dating between 100 bc and ad 300 on the basis of their major and trace element compositions. Samples from the western and eastern parts of the Roman Empire were analysed. Analytical data were obtained by means of a scanning electron microscope , energy-dispersive system (SEM,EDS, 63 samples analysed) and laser ablation , inductively coupled plasma , mass spectrometry (LA,ICP,MS, 41 samples analysed). Among the glass fragments analysed, dark brown, dark purple and dark green hues could be distinguished. Only among the dark green fragments could a clear compositional distinction be observed between fragments dated to the periods before and after ad 150. In the early samples (first century bc to first century ad), iron, responsible for the green hue, was introduced by using impure sand containing relatively high amounts of Ti. In contrast, a Ti-poor source of iron was employed, containing Sb, Co and Pb in trace quantities, in order to obtain the dark green colour in the later glass samples. The analytical results obtained by combining SEM,EDS and LA,ICP,MS are therefore consistent with a differentiation of glassmaking recipes, detectable in glass composition, occurring in the period around ad 150. [source]