Glass Science and Technology

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Novel Photonic Glasses for Fiber-Optic Amplifiers
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Heo, Jong
Development of novel glass hosts for the fiber-optic amplifiers was introduced with a special attention on the O-band amplifiers operating at 1.31 μm. Upon the addition of alkali halide (especially CsBr) into Ge-Ga-S glasses, the intensity of the 1.31 μm emission from Dy³⁺ (⁶F_(1 1/2)*⁶H_(9/2) →⁶H_(15/2)) increased sharply at the expense of the 1.75 μm emission intensity (⁶H_(1 1/2)→⁶Hi_(15/2)). The lifetimes of the 1.31 μm emission level also increased upto 1580 μs. The nearest neighbors of Eu³⁺ ions, or rare-earth ions in this glass, are composed of halogen ions that are part of well-structured complex such as tetrahedral [GaS_(3/2)Br]¯ subunit and/or Ga₂Br₆. Similar enhancement in the emission properties was also observed in Tm³⁺ and Ho³⁺-doped glasses with the addition of an appropriate amount of CsBr into sulfide glasses.
Glasses to Turn On Genes
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Hench, Larry L.
[no abstract available]
Biomimetic Preparation of Bioactive Layers
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Skrčená, A.; Hejda, M.; Cílová, Z.; Helebrant, A.
[no abstract available]
Crystalization in High Iron Containing Silicate Glasses - Electron Microscopy Investigation
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Völksch, Günter; Harizanova, Ruzha; Rüssel, Christian; Mitsche, Stefan; Pölt, Peter
[no abstract available]
Corrosion of Glass
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Helebrant, A.; Jiřička, A.; Jiřičková, J
The paper reviews the different models describing interaction between glasses and aqueous solutions. It is shown the development of kinetic and thermodynamic models (Rana & Douglas, HIaváč & Matěj, Isard et al., Boksay & Doremus, Strachan, Grambow, Conradt, Aagaard & Helgeson). The models are compared from the point of view of different mechanisms and partial processes considered during model development. Model based on combination of Boksay & Doremus and Strachan models is shown, considering the glass corrosion as a combination of three simultaneous processes: 1. Glass matrix dissolution with two subsequent steps (surface reaction and surface reaction products transport through the precipitated layer and/or through Solution layer adjacent to the glass surface) 2. Leaching of moveable ions (A⁺) due to interdiffusion of HsO⁺ - A⁺ 3. Precipitation of dissolved glass components and/or Solution components on the glass surface. Finally, the outlook for future development of glass corrosion modelling is suggested, based on combination of Boksay & Doremus, Strachan, Conradt and Aagaard & Helgeson approach.
Thermodynamics of glass melts and thermo-chemistry of glass forming batches
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Conradt, Reinhard
The paper deals with the thermodynamics of glass melts and glass forming batches. In a first step, an improved approach to the heat capacities of multi-component glass melts by the combination of a thermochemical model and the Adam-Gibbs equation is presented. Then, the heat demand of dolomite decomposition is reinvestigated. Finally, a proposition is made for the modelling of the batch-to-melt reaction path, yielding Information on both calcoric and rheological properties.
Characterization of Solid Weathering Products Formed in Polluted Atmospheres on Crystal Glass
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Rebroš, M.; Jamnický, M.; Kadlečíková, M.
The weathering of two different manufactured crystal glasses was studied. The glass samples were exposed to various polluted atmospheric environments with high relative humidity and at cyclic temperature changes. The chemical composition and the structure of solid weathering products were studied by means of scanning electron microscopy with energy dispersive X-ray microanalysis, Raman microscopy and partially X-ray diffraction. Several crystalline compounds created on sample surfaces such as various sulphates and carbonates were identified.
Bubling - Intensifying Mean of Glass Melting Process and its Mathematical Modeling
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Novák, J.; Kasa, S.
The method of 3D numerical modeling by means of the CDF program Fluent has been used to study the influence of bubbling on temperature and velocity fields in a gas heated melting furnace. Bubbling presence in the furnace has proved its intensifying influence on a melting process, which was manifested by positive influencing of glass melt temperature (higher heating up ). The same positive influence of bubbling has been noticed also in case of a glass melt flow. Bubbling in the furnace has resulted in the increase of glass melt velocity and, consequently, in speeding up the reactions between non-homogeneities and the melt, as well as in quicker glass melt refining. A double-row arrangement of bubbling nozzles has appeared to be more advantageous, as it lead to the global heating up in the furnace increased by several tens degrees ( 3 0 - 6 0 ° C ) and to the increase of velocity by about 30%.
Effect of Storage Terms and Conditions on Quality of Al-Na Silica Fiber Glass
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Setina, J.; Akishins, V.; Veveris, G.; Patmalnieks, A.
The surface of glass marbles for fiber after long term storage and experimental simulation of corrosion in solution has been studied. The corrosion products affect the structure and properties of fiber by remelting of glass marbles. The morphology and compositional profiles of glass marbles depending on the time and temperature of exposure were determined. The optimal proportion of sodium and aluminum oxides in glass and the suitable time of storage are established.
Structure and properties of alkali and alkali lead oxynitride phosphate glasses
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Muñoz, F.; Pascual, L.; Durán, A.; Montagne, L.; Berjoan, R.; Marchand, R.
The development ofmicroelectronics towards lower processing temperatures needs a parallel development of lower temperatures sealing materials. Due to particular thermal properties, such as high thermal expansion coefficient, A ,and low glass transition and dilatometric softening temperatures, Tg and Ts, phosphate glasses are of interest for application as low-temperature sealing glasses. An efficient method to significantly improve the accompanying poor chemical durability of these glasses is a partial anionic Substitution of nitrogen(Ν³¯)for oxygen (O²¯), which induces crosslinking between chains through covalent P-N bonds. New Li_(0.25)Na_(0.25)Pb_(0.25)PO_(3-3x/2)N_x phosphorus oxynitride glass compositions (0 < X ≤ 0.69) have been elaborated by thermal treatment of corresponding oxide base glasses in an hydrous ammonia atmosphere, at temperatures ranging from 600 to 750°C and for times up to 30h. The introduction of nitrogenin the glass network induces also a linear decrease in α, and a linear increase in Tg andTs, however without changing them too much. A structural study has been carried out using nuclearmagnetic resonance and x-ray photoelectron spectroscopies. ³¹P MAS NMR shows that the glass network is built up of PO₄, PO₃N and PO₂N₂ tetrahedral units. PO₄-PO₄, PO₄-PO₃N and PO₃N-PO₂N₂ connections, evidenced by ³¹P-MAS NMR, are homogeneously distributed within the glass network. XPS at the Nis core level indicates that nitrogen atoms substitute for both bridging and non-bridging oxygen atoms, as two-coordinated -N= (Nd) or three-coordinated -N< (Nt) species. A higher amount of Nd-type than Nt-type atoms is found for the highest nitrogen contents. ²³Na and ²⁰⁷Pb NMR results show that the nitrogen-oxygen substitution does not affect oxygen atoms coordinating modifier cations. The role played by lead in these "LINaPbPON" glasses is deduced from a comparison with the nitridation study in "LINaPON" and "NaPON" systems. The presence of Pb²⁺ cations has clearly an influence on the nitridation mechanism. They behave essentially as modifier cations, however they show with the nitrogen enrichment an increased network forming character.
Cathodic Behaviour of the Molybdenum Electrode in Glass Melt
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Matěj, J.; Čierna, V.; Hulínský, V.; Maryška, M.; Hurníková, J.
[no abstract available]
Thermal behaviour of the mixed (M₂O-PbO)-B₂O₃-P₂O₅ glasses
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Mošner, P.; Koudelka, L.
[no abstract available]
High temperature investigation of soda-lime-silicate glasses doped with manganese and chromium
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Kido, Ladislav; Müller, Matthias; Rüssel, Christian
[no abstract available]
Molecular dynamics of the oxynitride glasses
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Macháček, J.; Liška, M.; Gedeon, O.
Parameterisations of pair-potential functions were developed by means of ab-initio energy hyper-surface mapping of AI₂O₃, SiO₂*Si₃N₄, and AIN crystals. Molecular dynamics simulation was then performed for the 19.1Si₃N₄*80.9Al₂O₃ melt. The poor glass forming ability was confirmed by the phase separation, observed in simulated structure.
Verification of Released Energy in the Models Furnaces by Means of Thermo Vision
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Lisý, A.; Hamáček, L.
The distribution of released electric energy has been investigated on the two dimensional mathematical model of a full electric melting tank. The power fields were calculated for two chosen variants of electrode connection to the supply source. The physical model of heating system made from an electro-conductive foil and the method of monitoring released energy between electrodes by a thermo vision camera were used for verification of the calculated results.
The Effect of Stirrers at low Re Numbers
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Kasa, S.; Novotný, F.
During glass melt homogenisation, the stirrers are often required to show not only the homogenisation, but also a pumping effect. This effect can be achieved by means of two mechanisms. The first one is paddle uplift, applied for plane wings, airscrews, ventilation fans and turbines. This devices operates at high values of the Re number, usually 10⁵ - 10⁶ . Fig.1. The second phenomenon that can be used for pumping is a shearing force, appearing as a consequence of a drawing force which appears due to the movement of planes in a viscous liquid. Worms, extruders and feeders of various media, e.g. plastics, work on this principle. In liquids of high viscosity and with very slow movements resulting from this, inertia becomes negligible. The liquid moves only according to resultants of forces affecting at the moment. This flow is called creeping flow, or flow in Stokes' area. Worm pumps operate in this range. The mechanism of screw effect can be seen in Fig. 2. This devices operates at very low Re number e.g. for the transport of plastics polymers Re=0.006.
Forming Behavior and the Structure of Glasses
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Clare, Alexis G.; King, Wesley A.; LaCourse, William C.
The effect of forming on arsenic selenide glass fiber drawn under extreme conditions are discussed in detail. Differential Scanning Calorimetry (DSC) data are correlated with previously published time-of-flight (TOF) neutron scattering, nuclear quadrupole resonance (NOR) data to argue that the structure of As₂Se₃ glass pulled under extreme conditions is oriented and that some of the extreme structures imposed in the arsenic selenide fibers relax at room temperature. A model is proposed for the sequence of events suggesting a regime of interchain breakage followed by reformation followed by intrachain breakage. Also evident are unexpected small ring structures as a result of low temperature healing process.
Fundamental research on twofold phase formation of apatite solid-solutions and leucite in glass-ceramics
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) van 't Hoen, Christian; Höland, Wolfram; Rheinberger, Volker
In this study the phase formation of apatites in the multi-component SiO₂-Al₂O₃-Na₂O-K₂O-GaO/SrO-P₂O₅-F system was investigated. Based on a special composition GaO was partially and completely substituted by SrO. Room and high temperature X-ray diffraction (RT- and HT-XRD) and scanning electron microscopy (SEM) were used to characterize the phase formation. The results of this study showed a formation of two different apatite solid-solutions, Sr_(7.3)Ca_(2.7)(PO₄)₆F₂ and Sr₆Ca₄(PO₄)₆F₂ and Sr-apatite Sr₅(PO₄)₃F. Leucite formation is based on surface crystallization. The conclusion is a twofold volume and surface nucleation and crystallization mechanism.
Effect of an addition of TiO₂ on the thermal stability of Li₂O.SiO₂ glasses -application of various criteria
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Jóna, E.; Nemčeková, K.; Šimon, P.; Plško, A.; Ondrušová, D.
To compare the thermal stability of Li₂O.2SiO₂ and Li₂O.2SiO₂.0.1TiO₂ glasses, various criteria have been used. Not only characteristic temperatures, values of activation energy (E) and enthalpy changes (ΔΗ), but also the combined criteria E/RT and k_f(T) = A exp [(-E/RT) (T_p-T_f)/T_f] (T_p is the maximum peak temperature, T_f is the inflection point temperature on the differential thermal analysis curves) have been taken into account. The results indicate that order of the thermal stability against of different glass systems crystallization depends not only on their composition but also on the mechanism of crystallization which is connected with the used parameter.
Modeling, simulation and control of glass feeding
(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Havel, P.; Horáček, P.
This paper presents a nontraditional modeling approach to a glass production process in order to facilitate control design. A real distributed-parameter system (glass feeder) is simplified to a lumped-parameter system and then bond graphs are used to develop a model whose parameters are identified from physical insight and historical records. The adopted modeling approach yields a reduced-order nonlinear model, which is much less computationally demanding than CFD models. Moreover, it is valid in a wider range of temperatures compared to black-box linear models often used in control design. As an example, an LQ controller based on a linearized model is designed and validated on the nonlinear model.

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