Glasses

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Kinds of Glasses

  • bioactive glasses
  • bulk metallic glasses
  • metallic glasses
  • molecular glasses
  • phosphate glasses
  • silicate glasses


  • Selected Abstracts


    ISOTOPIC DISCRIMINANTS BETWEEN LATE BRONZE AGE GLASSES FROM EGYPT AND THE NEAR EAST

    ARCHAEOMETRY, Issue 3 2010
    P. DEGRYSE
    This paper presents oxygen, strontium and neodymium isotopic analysis from a series of Late Bronze Age glasses from Egypt and Mesopotamia. It was found that oxygen and neodymium isotopes alone cannot readily distinguish between glasses from the various sites. However, combined Sr and Nd isotope analysis separate the data into three groups: an Egyptian group with relatively low Sr and Nd ratios; a Late Bronze Age (LBA) Nuzi group with high Sr and low Nd ratios; and an intermediate Sr and high Nd ratio grouping of glasses from Tell Brak. These findings suggest that most of the glass from Nuzi and Tell Brak had different raw materials and hence the glass was probably produced at different manufacturing sites. However, one glass ingot found at Tell Brak (TB1) appears to have Nuzi-type Sr,Nd characteristics. This is the first positive identification of multiple production sites in LBA Mesopotamia and an exceptional example of a glass that may have been exchanged from one LBA site to another. [source]


    THE APPLICATION OF TIME-OF-FLIGHT SECONDARY ION MASS SPECTROMETRY (ToF-SIMS) TO THE CHARACTERIZATION OF OPAQUE ANCIENT GLASSES*

    ARCHAEOMETRY, Issue 6 2009
    F. J. M. RUTTEN
    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used, for the first time, for the characterization of opaque ancient glasses. Isotope-specific chemical imaging with sub-micron resolution enabled the separate analysis of opacifiying inclusions and the surrounding glass matrix. Phase identification has been demonstrated and quantification of the matrix composition has been investigated by use of Corning Glass Standard B as a model. Trace element detection limits are typically in the range 0.5,5.0 ppm atomic,in favourable cases down to 0.01 ppm. For the analysis of inclusions in particular, this has the potential to provide new information of use in establishing provenance and trade routes by ,fingerprinting' as well as the investigation of manufacturing techniques, as demonstrated by comparisons between glasses and with EDX data from the same samples. [source]


    THE BLUE ENAMELS IN THE BAROQUE DECORATIONS OF THE CHURCHES OF PALERMO, SICILY: FE2+ -COLOURED GLASSES FROM LIME KILNS*

    ARCHAEOMETRY, Issue 2 2009
    G. ARTIOLI
    Deep blue glasses coloured by octahedral Fe2+ cations are often reported as textbook examples of blue pigmentation. However, despite the possibility of laboratory synthesis under reducing conditions, to date there are no well-reported occurrences of their production and use in the past. A thorough historical, ethnographic, mineralogical, and chemico-physical investigation of the ,smaltini di calcara' from several baroque churches in Palermo, Sicily, has revealed that the blue enamels widely used for altar decorations in the 17th and 18th centuries are actually a unique case of ancient blue glasses pigmented by divalent iron cations in distorted octahedral coordination. This mixed-alkali glass was accidentally produced under severely reducing conditions in the local kilns during production of lime. [source]


    Reflections Off My Reading Glasses

    ACADEMIC EMERGENCY MEDICINE, Issue 2005
    Academic Emergency Medicine, MS Editor-in-Chief, Michelle H. Biros MD
    No abstract is available for this article. [source]


    An Ab Initio Molecular Dynamics Study of Bioactive Phosphate Glasses,

    ADVANCED ENGINEERING MATERIALS, Issue 7 2010
    Emilia Tang
    First principles molecular dynamics simulations of ternary phosphate-based glasses P2O5CaONa2O (PBGs) have been carried out in order to provide an accurate description of the local structure and properties of these important materials for biomedical applications. The structures of PBGs with compositions (P2O5)0.45(CaO)x(Na2O)0.55,,,x (x,=,0.30, 0.35, and 0.40) were generated using a full ab initio molecular dynamics melt-and-quench procedure. The analysis of the structure of the glasses at 300,K shows the prevalence of the metaphosphate Q2 and pyrophosphate Q1 species, whereas the number of Q3 units, which constitute the three-dimensional phosphate network, significantly decreases with the increase in calcium content in the glass. Calculation of the pair and angular distribution functions suggests that the rigidity of the phosphate tetrahedral glass network increases with the concentration of calcium, an observation which is interpreted in terms of the tendency of Ca2+ to be a stronger coordinator than sodium. [source]


    The Effects of Casting Temperature on the Glass Formation of Zr-Based Metallic Glasses,

    ADVANCED ENGINEERING MATERIALS, Issue 12 2009
    Jie Mao
    Abstract The glass1-forming ability of two alloys, Zr64.9Al7.9Ni10.7Cu16.5 and Zr47Cu37.5Ag7.5Al8, prepared by arc-melting a mixture of Zr, Cu, Al, Ni and Ag elements is studied as a function of casting temperature. Other processing parameters such as the alloy melt mass, and the vacuum and injection pressures during the copper-mold-casting process are kept constant so just the influence of the casting temperature is considered. The casting temperature determines the characteristics of the liquid melt and the cooling rate. The glass-forming ability is discussed in terms of dissipation of pre-exiting, metastable local-ordering clusters that act as nucleation sites promoting crystallization, the cooling rate at high casting temperatures, and the presence of oxygen in the alloys, which is increased at high casting temperatures. It is found that the glass-forming ranges of alloys shrink as the glass-forming size approaches a critical value. The optimum temperatures are around 1450,K and 1550,K for Zr64.9Al7.9Ni10.7Cu16.5 and Zr47Cu37.5Ag7.5Al8 alloys respectively. The alloys were studied by XRD, TEM, oxygen-level determination, and DSC. [source]


    In vitro Chemical Reactivity of Doped Bioactive Glasses: an Original Approach by Solid-State NMR Spectroscopy

    ADVANCED ENGINEERING MATERIALS, Issue 8 2009
    Elodie Dietrich
    The control of the in vitro and in vivo bioactivity, as well as the chemical reactivity of melt-derived glasses is an important state in the biomaterials field. The present work explores the local structure of bioactive glasses before and after in vitro assays in simulated body fluid. This study by solid-state MAS,NMR constitutes an original approach to the understanding of the bioactivity process. [source]


    Statistic Analysis of the Mechanical Behavior of Bulk Metallic Glasses,

    ADVANCED ENGINEERING MATERIALS, Issue 5 2009
    Hai Bin Yu
    The Weibull distribution is used to characterize the mechanical behavior of a bulk metallic glass (BMG). The strength of the BMG is quite stable, while the plasticity is much less stable. The reason is attributed to the fraction and distribution of free volumes, which are sensitive to processing conditions. The results demonstrate the close relationship between the distribution and fraction of free volumes and plasticity in BMGs. [source]


    Designing Ductile Zr-Based Bulk Metallic Glasses with Phase Separated Microstructure,

    ADVANCED ENGINEERING MATERIALS, Issue 5 2009
    Xinghao Du
    Using the thermodynamic computation, the phase-separated Zr-based bulk metallic glasses with a enhanced plasticity up to 20% are developed. The as-cast microstructure is characterized by the macroscopic heterogeneities consisting of the phase-separated regions and glassy matrix regions. The microscaled phase-separated feature is the cause of the remarkable plasticity, and the homogeneous and concurrent formation of multiple shear bands is crucial for the plasticity improvement in metallic glasses. [source]


    Molecular Origins of the Mechanical Behavior of Hybrid Glasses

    ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
    Mark S. Oliver
    Abstract Hybrid organic-inorganic glasses exhibit unique electro-optical properties along with excellent thermal stability. Their inherently mechanically fragile nature, however, which derives from the oxide component of the hybrid glass network together with the presence of terminal groups that reduce network connectivity, remains a fundamental challenge for their integration in nanoscience and energy technologies. We report on a combined synthesis and computational strategy to elucidate the effect of molecular structure on mechanical properties of hybrid glass films. We first demonstrate the importance of rigidity percolation to elastic behavior. Secondly, using a novel application of graph theory, we reveal the complex 3-D fracture path at the molecular scale and show that fracture energy in brittle hybrid glasses is fundamentally governed by the bond percolation properties of the network. The computational tools and scaling laws presented provide a robust predictive capability for guiding precursor selection and molecular network design of advanced hybrid organic-inorganic materials. [source]


    Engineering Disorder: Engineering Disorder in Superdiffusive Lévy Glasses (Adv. Funct.

    ADVANCED FUNCTIONAL MATERIALS, Issue 6 2010
    Mater.
    Engineering disorder makes it possible to realize materials with advanced optical properties. On page 965, Bertolotti et al. report the recipe for Lévy glasses, strongly inhomogeneous disordered systems displaying superdiffusive light transport. The degree of superdiffusion is fine-tuned by embedding transparent spheres varying in size by orders of magnitude in a scattering medium. [source]


    Engineering Disorder in Superdiffusive Lévy Glasses

    ADVANCED FUNCTIONAL MATERIALS, Issue 6 2010
    Jacopo Bertolotti
    Abstract Disorder is known to have a substantial impact on light transport in optical materials. In particular, when properly tuned, disorder can unveil optical properties that common, periodically patterned materials do not possess. In this paper, a method to realize disordered dielectric materials dubbed Lévy glasses, in which light transport is superdiffusive, is presented. The degree of superdiffusion is set by engineering the spatial inhomogeneity of the scatterer density in the material. A model that relates the microscopic parameters to the macroscopic transport properties of Lévy glasses is given and the signature of superdiffusion on the transmission profile in a slab configuration is shown experimentally. [source]


    Electroluminescence and Laser Emission of Soluble Pure Red Fluorescent Molecular Glasses Based on Dithienylbenzothiadiazole

    ADVANCED FUNCTIONAL MATERIALS, Issue 18 2009
    Ju Huang
    Abstract Soluble molecular red emitters 1a/1b are synthesized by Stille coupling from 2-(3,5-di(1-naphthyl)phenyl)thiophene precursors. The compounds show emission maxima at ca. 610,nm in CH2Cl2 solution and 620,nm in solid films. Replacing the n -hexyl substituent by 4- sec -butoxyphenyl produces a marked increase of glass transition temperature (Tg) from 82,°C to 137,°C and increases the solubility in toluene and p -xylene, thus improving the film-forming properties. Cyclic voltammetry shows that the compounds can be reversibly oxidized and reduced around +1.10 and ,1.20,V, respectively. A two-layered electroluminescent device based on 1b produces a pure red light emission with CIE coordinates (0.646, 0.350) and a maximal luminous efficiency of 2.1,cd A,1. Furthermore, when used as a solution-processed red emitter in optically pumped laser devices, compound 1b successfully produces a lasing emission at ca. 650,nm. [source]


    Synthesis and Structure,Property Relations of a Series of Photochromic Molecular Glasses for Controlled and Efficient Formation of Surface Relief Nanostructures

    ADVANCED FUNCTIONAL MATERIALS, Issue 16 2009
    Roland Walker
    Abstract This paper reports on the synthesis and properties of a new series of photochromic molecular glasses and their structure,property relations with respect to a controlled and efficient formation of surface relief nanostructures. The aim of the paper is to establish a correlation between molecular structure, optical susceptibility, and the achievable surface relief heights. The molecular glasses consist of a triphenylamine core and three azobenzene side groups attached via an ester linkage. Structural variations are performed with respect to the substitution at the azobenzene moiety in order to promote a formation of a stable amorphous phase and to tune absorption properties and molecular dynamics. Surface relief gratings (SRGs) and complex surface patterns can easily be inscribed via holographic techniques. The modulation heights are determined with an equation adapted from the theory for thin gratings, and the values are confirmed with AFM measurements. Temperature-dependent holographic measurements allow for monitoring of SRG build-up and decay and the stability at elevated temperatures, as well as determination of the glass transition temperature. SRG modulation heights of above 600,nm are achieved. These are the highest values reported for molecular glasses to date. The surface patterns of the molecular glasses are stable enough to be copied in a replica molding process. It is demonstrated that the replica can be used to transfer the surface pattern onto a common thermoplastic polymer. [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]


    Antimicrobial Gallium-Doped Phosphate-Based Glasses,

    ADVANCED FUNCTIONAL MATERIALS, Issue 5 2008
    Sabeel P. Valappil
    Abstract Novel quaternary gallium-doped phosphate-based glasses (1, 3, and 5 mol % Ga2O3) were synthesized using a conventional melt quenching technique. The bactericidal activities of the glasses were tested against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Clostridium difficile) bacteria. Results of the solubility and ion release studies showed that these glass systems are unique for controlled delivery of Ga3+. 71Ga NMR measurements showed that the gallium is mostly octahedrally coordinated by oxygen atoms, whilst FTIR spectroscopy provided evidence for the presence of a small proportion of tetrahedral gallium in the samples with the highest gallium content. FTIR and Raman spectra also afford an insight into the correlation between the structure and the observed dissolution behavior via an understanding of the atomic-scale network bonding characteristics. The results confirmed that the net bactericidal effect was due to Ga3+, and a concentration as low as 1 mol % Ga2O3 was sufficient to mount a potent antibacterial effect. The dearth of new antibiotics in development makes Ga3+ a potentially promising new therapeutic agent for pathogenic bacteria including MRSA and C. difficile. [source]


    High-Modulus Organic Glasses Prepared by Physical Vapor Deposition

    ADVANCED MATERIALS, Issue 1 2010
    Kenneth L. Kearns
    Extraordinarily stable organic glasses are prepared by physical vapor deposition using indomethacin (IMC) or trisnaphthylbenzene. Utilizing Brillouin light scattering (BLS), the elastic moduli of these stable glasses (SG) are found to exceed those of ordinary glass (OG) by up to 19%. Such high-modulus glasses take more than 104 times longer than the structural relaxation time to transform to the supercooled liquid (SCL). [source]


    Bulk Metallic Glasses with Functional Physical Properties (Adv. Mater.

    ADVANCED MATERIALS, Issue 45 2009
    45/2009)
    [source]


    Bulk Metallic Glasses with Functional Physical Properties

    ADVANCED MATERIALS, Issue 45 2009
    W. H. Wang
    Abstract In this review, we report on the formation of a variety of novel, metallic, glassy materials that might well have applications as functional materials. The metallic glasses, with excellent glass-forming ability, display many fascinating properties and features such as excellent wave-absorption ability, exceptionally low glass-transition temperatures (,35,60,°C) approaching room temperature, ultralow elastic moduli comparable to that of human bone, high elasticity and high strength, superplasticity and polymer-like thermoplastic formability near room temperature, an excellent magnetocaloric effect, hard magnetism and tunable magnetic properties, heavy-fermion behavior, superhydrophobicity and superoleophobicity, and polyamorphism, all of which are of interest not only for basic research but also for technological applications. A strategy based on elastic-moduli correlations for fabrication of bulk metallic glasses (BMGs) with controllable properties is presented. The work has implications in the search for novel metallic glasses with unique functional properties, for advancing our understanding of the nature and formation of glasses, and for extending the applications of the materials. [source]


    Metallic Glasses: Nanoscale Solute Partitioning in Bulk Metallic Glasses (Adv. Mater.

    ADVANCED MATERIALS, Issue 3 2009
    3/2009)
    Devitrification of bulk metallic glass leads to novel microstructures with high-density nanoscale crystalline precipitates evenly distributed in a glassy matrix. Xun-Li Wang and co-workers report on p. 305 that significant chemical segregation is revealed in unprecedented detail by atom-probe tomography. This level of detail is crucial for understanding the interference peaks observed in small-angle X-ray and neutron scattering experiments. [source]


    Nanoscale Solute Partitioning in Bulk Metallic Glasses,

    ADVANCED MATERIALS, Issue 3 2009
    Ling Yang
    Devitrification of bulk metallic glass leads to a novel microstructure, with high-density nanoscale crystalline precipitates evenly distributed in a glassy matrix. Significant chemical segregation is revealed at unprecedented detail by atom-probe tomography. This level of detail is crucial for understanding the interference peaks observed in small-angle X-ray and neutron scattering experiments, an unsolved mistery for over a decade. [source]


    Dielectric Relaxation in CaO,Bi2O3,B2O3 Glasses

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2010
    Koushik Majhi
    Glasses in the system CaO,Bi2O3,B2O3 (in molar ratio) have been prepared using melt-quenching route. Ion transport characteristics were investigated for this glass using electric modulus, ac conductivity and impedance measurements. The ac conductivity was rationalized using Almond,West power law. Dielectric relaxation has been analyzed based on the behavior of electric modulus behavior. The activation energy associated with the electrical relaxation determined from the electric modulus spectra was found to be 1.76 eV, close to that the activation energy for dc conductivity (1.71 eV) indicating that the same species took part in both the processes. The stretched exponent , (0.5,0.6) is invariant with temperature for the present glasses. [source]


    High-Modulus Spin-On Organosilicate Glasses for Nanoporous Applications,

    ADVANCED MATERIALS, Issue 5 2007
    W. Ro
    Both the modulus and hardness of a conventional methylsilsesquioxane-type organosilicate, typically synthesized from the methyltrimethoxysilane monomer, can be substantially improved by incorporating organic bridging units through additions of the bis(triethoxysilyl)ethane monomer. The microstructural basis for these enhanced properties is described in this Communication. [source]


    Selenium-Based Glasses and Glass Ceramics Transmitting Light from the Visible to the Far-IR

    ADVANCED MATERIALS, Issue 1 2007
    L. Calvez
    An innovative glass/glass ceramic based on the GeSe2,Ga2Se3,CsCl system is reported. This material is the first reported glass/glass ceramic transparent from the visible to the far-IR, has improved mechanical properties over selenide glasses, and is compatible with high-precision molding, making it suitable for applications in thermal imaging. [source]


    Boson Peak, Elastic Properties, and Rigidification Induced by the Substitution of Nitrogen for Oxygen in Oxynitride Glasses

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010
    Nicolas F. Richet
    The effects of the substitution of nitrogen for oxygen on the heat capacity and vibrational entropy of three yttrium aluminosilicate glasses with 0, 3.4, and 7.4 mol% Si3N4 have been investigated from 10 to 300 K. The partial molar heat capacity and entropy of Si3N4 calculated from these and previous measurements indicate stronger average bonding than for SiO2 units, whereas the values derived for Y2O3 are consistent with the dual network modifying and Al3+ charge-compensating role of yttrium. The low-frequency part of the vibrational densities of states g(,) and the boson peaks g(,)/,2 derived from the inversion of the heat capacities indicate that nitrogen rigidifies the TO4 (T=Si, Al) tetrahedral network and that yttrium hampers the librational motion of the AlO4 tetrahedra, which contribute to the excitations associated with the boson peak. Along with data reported previously for borate and silicate glasses, these results for oxynitrides show a general monotonically increasing relation between transverse acoustic velocities and the temperature of the calorimetric boson peak. Illustrating the universal phenomenology of the boson peak, all these data collapse on the same master curve when plotted in a reduced form. [source]


    Local Heating from Silver Nanoparticles and Its Effect on the Er3+ Upconversion in Oxyfluoride Glasses

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010
    Chao Liu
    The effect of silver (Ag) nanoparticles on the upconversion emission properties of Er3+ ions in oxyfluoride glasses was investigated, and a mechanism of the energy transfer proposed. The integrated intensity ratios between 522 and 545 nm emission bands of Er3+ ions in glasses containing Ag nanoparticles were strongly dependent on the size of the Ag nanoparticles as well as on the intensity of the 800 nm excitation laser. When the absorption of Ag nanoparticles overlapped with the 2H11/2 and 4S3/2 energy levels in Er3+ ions, a strong energy transfer occurred from Er3+: 2H11/2, 4S3/2 levels to Ag nanoparticles. This energy was then converted to a temperature rise in the vicinity of Er3+ ions, eventually leading to the large increase in the integrated intensity ratios. The estimated effective temperature was approximately 200 K higher than the experimental temperature when the excitation power was 700 mW. [source]


    Quantification of Chemical Striae in Inorganic Melts and Glasses through Picture Processing

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010
    Martin Jensen
    Chemical striations occur in various types of inorganic melts like lava and glass melts, and affect the physical properties of materials. This paper reports a quantitative study of the chemical striations in iron-rich aluminosilicate melts and glasses. In this study, an integrated method has been established, which consists of sample preparation, image acquiring, Fourier Transformation, and characteristic value determination. The principle of the established method is illustrated by picture processing-based simulation. The extent of the chemical striations and the diffusion length of the striae can be measured using this method. It is found that the extent of the chemical striations is rather sensitive to the melting technique. Furthermore, the impact of chemical diffusion and stirring on the extent of striations is revealed using the picture processing-based simulation approach. The diffusion process eliminates small striae and reduces the intensity of the larger ones. At a constant temperature, the diffusion determines the transformation rate of an inhomogeneous melt into a homogeneous one. During stirring, the size distribution of the large striae becomes broader, but the overall intensity of the striae becomes smaller. [source]


    Photo-Induced Effect in Heavy Metal Oxide Glasses

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2010
    Jong Heo
    Photo-induced phenomena in binary (PbO,Ga2O3) and ternary (PbO,Bi2O3,Ga2O3) heavy metal oxide glasses were investigated. A red shift up to ,0.05 eV in the absorption edge of 75PbO,25Ga2O3 glass (mol%) was observed by illuminating the subbandgap light for 30 min. This shift was completely erased by the heat treatment near the glass transition temperature. Refractive index of the glass at 600 nm also increased ,0.011 by the illumination. It is believed that the presence of lone-pair electrons associated with Pb-polyhedra is essential to realize a reversible photo-induced effect in these oxide glasses. [source]


    Empirical Equation for Calculating the Density of Oxide Glasses

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2010
    Seiji Inaba
    The density of oxide glass including silicate, borate, phosphate, tellurite, and germanate glasses were measured using the Archimedes method. On the assumption that the ionic packing ratio is approximately a constant independent of chemical composition, an empirical equation for estimating the density from chemical composition was proposed. The calculated values are in reasonable agreement with the corresponding measured ones. [source]


    Broadband Near-IR Emission in Tm/Er-Codoped GeS2,In2S3 -Based Chalcohalide Glasses

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2009
    Yinsheng Xu
    The near IR emission spectra of Tm/Er-codoped GeS2,In2S3 -based chalcohalide glasses are studied with an 808 nm laser as excitation source. A broad emission with a full-width at half-maximum of ,170 nm is recorded in a 0.5Tm2S3,0.1Er2S3 -codoped 70GeS2,20In2S3,10CsBr (in mol%) glass. The luminescence mechanisms are discussed with different CsI concentration, different halogen atoms, and different In content. These results suggest that both halogen (X) atoms and [InSxX4,x] structural units can enhance the emission intensity located at 1460 nm. [source]