Composition Of Glass Matrix Research Articles

Photo‐Thermo‐Refractive Glasses: Effects of Dopants on Their Ultraviolet Absorption Spectra

Data accumulated on the UV spectra of photo‐thermo‐refractive glasses known to be a new class of photo‐sensitive materials for nanophotonics is discussed. The paper is aimed to providing specialists in the applied photonics with a complete self‐consistent block of the latest information on the UV spectral manifestations of various oxidation states of dopants and on the redox balance between these states. For all oscillators related to the oxidation states of dopants such as cerium, silver, and antimony, the spectroscopic parameters are computed and analyzed. Intercomparison of the data is conducted in terms of the redox reactions between particular oxidation states of dopants. The effects of bromine in the matrix glass composition on the parameter magnitudes for the Ag+ and Ce4+ states are demonstrated and the origin of the effects is discussed. The roles of atomary silver and antimony in the Sb3+ state as strong reducers with respect to cerium in the Ce4+ state are analyzed. Estimates for the molar fractions of Ce3+ and Ce4+ states in the glasses with various dopant combinations are discussed. A possibility to reconstruct the absorption spectrum of commercial photo‐thermo‐refractive glass using data obtained on the parameter magnitudes for the oxidation states of dopants is shown.

Phase-equilibrium geobarometers for silicic rocks based on rhyolite-MELTS—Part 3: Application to the Peach Spring Tuff (Arizona–California–Nevada, USA)

Establishing the depths of magma accumulation is critical to understanding how magmas evolve and erupt, but developing methods to constrain these pressures is challenging. We apply the new rhyolite-MELTS phase-equilibria geobarometer—based on the equilibrium between melt, quartz, and two feldspars—to matrix glass compositions from Peach Spring Tuff (Arizona–California–Nevada, USA) high-silica rhyolite. We compare the results to those from amphibole geothermobarometry, projection of glass compositions onto the haplogranitic ternary, and glass SiO2 geobarometry. Quartz + 2 feldspar rhyolite-MELTS pressures span a relatively small range (185–230 MPa), consistent with nearly homogeneous crystal compositions, and are similar to estimates based on projection onto the haplogranitic ternary (250 ± 50 MPa) and on glass SiO2 (255–275 MPa). Amphibole geothermobarometry gives much wider pressure ranges (temperature-independent: ~65–300 MPa; temperature-dependent: ~75–295 MPa; amphibole-only: ~80–950 MPa); average Anderson and Smith (Am Mineral 80:549–559, 1995) + Blundy and Holland (Contrib Miner Petrol 104:208–224, 1990) or Holland and Blundy (Contrib Miner Petrol 116:433–447, 1994—Thermometer A, B) pressures are most similar to phase-equilibria results (~220, 210, 190 MPa, respectively). Crystallization temperatures determined previously with rhyolite-MELTS (742 °C), Zr-in-sphene (769 ± 20 °C), and zircon saturation (770–780 °C) geothermometry are similar, but temperatures from amphibole geothermometry (~450–955 °C) are notably different; the average Anderson and Smith + Holland and Blundy (1994—Thermometer B; ~710 °C) temperature is most consistent with previous estimates. The rhyolite-MELTS geobarometer effectively culls glass compositions affected by alteration or analytical issues; Peach Spring glass compositions that yield pressure estimates reveal a tight range of plausible Na2O and K2O contents, suggesting that low Na2O and high K2O contents of many Peach Spring samples are due to alteration. Use of altered whole-pumice compositions in rhyolite-MELTS simulations is likely the cause of the incorrect crystallization sequence reported previously for Peach Spring compositions. Using the rhyolite-MELTS geobarometer, we estimate a more realistic composition for Peach Spring Tuff high-silica rhyolite, and the calculated composition finds close matches with some analyzed rocks and results in the expected sequence of crystallization.

Tunable luminescence of Dy3+ single-doped and Dy3+/Tm3+ co-doped tungsten borate glasses

RE3+ (RE3+=Tm3+, Dy3+) ion single and co-doped tungsten borate glasses for white light emitting diodes (LEDs) were prepared by melt quenching method. Emission and excitation spectra of the glasses were measured. The color of luminescence can be tuned by changing the composition of glass matrix or the concentrations of Tm3+ and Dy3+ ions. White light emission can be achieved from 0.5Dy3+ single-doped 15WO3–25La2O3–60B2O3 and 0.4Tm3+/1.5Dy3+ co-doped 50WO3–25La2O3–25B2O3 glasses. In addition, energy transfers between Tm3+ and Dy3+ were also analyzed. The Dy3+/Tm3+ co-doped tungsten borate glasses may be potential candidates for white LED application.

Polarized luminescence of erbium and thulium ions in glasses

The partially polarized luminescence of erbium- and thulium-doped glasses exited by the linearly polarized laser radiation was observed. The dependence of the polarization degree on the RE ions concentration and on the glass matrix composition were investigated. For erbium- and thulium-doped glasses, the maximum polarization degree was shown to reach ∼0.1% and ∼1%, respectively. The polarized luminescence properties of RE-doped glasses were explained based on the model of an optical oscillator.

Tb/Eu共掺锌硼磷酸盐白光发光玻璃的制备及其发光性能

Tb /Eu co-doped zinc borophosphate glasses were successfully synthesized by melt quenching method.The effect of glass matrix composition and rare erath ions concentration were discussed.The structural and luminescent properties were characterized by Fourier transform infrared(FT-IR) spectra,absorption spectra,photoluminescence(PL) spectra,fluorescence lifetimes and colorimetric analysis.Eu3+ ions were partly reduced to Eu2+ during the synthesization in air.Under380 nm excitation,white light emission was observed composited by emission at 612 nm and 590 nm for Eu3+,544 nm and 488 nm for Tb3+,and 430 nm for Eu2+.The FT-IR spectra showed that the structure of glass matrix changed when B2O3 content increased,which affected the Eu2+/Eu3+ ratio in glass samples.The spectra results show that Eu2+ ions are donors which can transfer energy to Eu3+ and Tb3+.Lifetime analysis proved that Tb3+ions can transfer energy to Eu3+through nonradiative transition.The luminescence intensity and emission color can be efficiently controlled by changing glass composition and rare earth ion concentration.Optimized white light with CIE(0.318 7,0.286 1) and correlated color temperature at 6 480 K was obtained when the mole fractions of Eu and Tb were both 1.5%.

Luminescence of silver molecular clusters in photo-thermo-refractive glasses

The luminescence spectra of silver molecular clusters in photo-thermo-refractive glasses are investigated in detail before and after the UV irradiation and also after the heat treatment of the samples. In the initial photo-thermo-refractive glass sample, silver is shown to occur in the form of Ag+ ions and positively charged molecular clusters. After the UV irradiation with the wavelength corresponding to the Ce3+ ion absorption, these species are assumed to pass partially to the neutral state, thus forming the Ag0 atoms and neutral molecular clusters such as Ag2, Ag3, and Ag4 that exhibit an intense luminescence in the visible. A subsequent heat treatment at temperatures below the glass transition one results in an increase in the intensity of the luminescence due to an increase in the concentration of neutral molecular clusters. Also investigated are the influence of halogens such as Cl and Br in glass matrix composition on the luminescence of silver molecular clusters in photo-thermorefractive glasses and the effect of temperature on the luminescence spectra of photo-thermorefractive glasses.

The Effect of Cerium Reduction on Light Emission in Cerium-containing 20Y2O3-25Al2O3-55SiO2 Glass

The effect of cerium concentration and the addition of Sb2O3 on the light emission of cerium-contained glass were investigated. The glass matrix composition was 20Y2O3-25Al2O3-55SiO2, the CeO2 concentration ranged from 0.05 to 0.5 mol%, and Sb2O3 was added at concentrations of 0.02 to 0.1 mol%. The Ce3+ and Ce4+ absorption bands were observed at approximately 330 nm and 240 nm, respectively. A broad emission band at 400 nm, due to the 4f-5d transition of the Ce3+ ion, was observed under illumination by a UV light at 330 nm. The photoluminescence intensity of Ce3+ had a maximum value at a CeO2 concentration of 0.1 mol%. Adding Sb2O3 decreased the Ce4+ absorption intensity and enhanced the light emission intensity of Ce3+ by about 45%.

A method for estimating the activity of titania in magmatic liquids from the compositions of coexisting rhombohedral and cubic iron–titanium oxides

A method is described for estimating the activity of titania (TiO2) in a magmatic liquid from the compositions of coexisting cubic oxide (spinel) and rhombohedral oxide (ilmenite). These estimates are derived from the thermodynamic models of Ghiorso and Evans (Am J Sci 308:957–1039, 2008; see also Sack and Ghiorso in Contrib Mineral Petrol 106:474–505, 1991a; Am Mineral 76:827-847, 1991b) and may be computed self consistently along with temperature and oxygen fugacity for an assumed pressure. The method is applied to a collection of 729 naturally occurring oxide pairs from rhyolites and dacites. For this suite of oxides, values of titania activity relative to rutile saturation range from 0.3 to 0.9. Genetically related groups of oxide pairs display activity–temperature trends with negative slopes at higher activities (0.6–0.9) or positive slopes at lower activities (0.3–0.7). Thermodynamic analysis supports the assumption of two-oxide, liquid equilibrium for the former group, but suggests that such an interpretation for oxide sequences with positive activity–temperature trends may be problematic. Application of the estimation method to oxide pairs from the Shiveluch Volcano and the Bishop Tuff reveals that the former are consistent with having equilibrated with known matrix glass compositions, whereas the latter pairs are inconsistent with equilibration with pre-eruptive liquids trapped in quartz inclusions.

Contrasting compositional trends of rocks and olivine-hosted melt inclusions from Cerro Negro volcano (Central America): implications for decompression-driven fractionation of hydrous magmas

Melt inclusions in olivine Fo83–72 from tephras of 1867, 1971 and 1992 eruptions of Cerro Negro volcano represent a series of basaltic to andesitic melts of narrow range of MgO (5.6–8 wt %) formed by ~46 wt % fractional crystallization of olivine (~6 wt %), plagioclase (~27 wt %), pyroxene (~13 wt %) and magnetite (<1 wt %) from primitive basaltic melt (average SiO2 = 49 wt %, MgO = 7.6 wt %, H2O = 6 wt %) as it ascended to the surface from the depth of about 14 km. The crystallization occurred at increasing liquidus temperature from 1,050 to 1,090 °C in the pressure range from 400 to 50 MPa and was induced by release of mixed H2O–CO2 fluid from the melt at decreasing pressure. Matrix glass compositions fall at the high-Si end of the melt inclusion trend and represent the final stage of melt crystallization during and after eruption. The bulk compositions of erupted Cerro Negro magmas (tephras and lavas) range from high- to low-MgO (3–10 wt %) basalts, which form a compositional array crossing the trend of melt inclusions so that virtually no rock from Cerro Negro has composition akin to true melt represented by the inclusions. The variations of the bulk magma (rocks) and melt (melt inclusions) compositions can be generated in a dyke connecting a deep primitive magma reservoir with the Cerro Negro edifice. While the melt inclusions represent the compositional trend of instantaneous melts along the magma pathway at decreasing pressure and H2O content, occurrence of low-Mg to high-Mg basalts reflects the process of phenocryst re-distribution in progressively evolving melt. The crystallization scenario is anticipated to operate everywhere in dykes feeding basaltic volcanoes and can explain the predominance of plagioclase-rich high-Al basalts in island arc as well as typical compositional variations of magmas during single eruptions.

Crystallization Properties of Ge-Se-Bi Thermoelectric Glasses

In the present work, a series of glass samples in Ge-Se-Bi system are prepared. XRD analysis is made on samples for identifying the type of precipitated crystals from glass matrices. Effects of glass matrix composition on crystallization behaviors are discussed. Results show that Ge and Bi content of glasses in the Ge-Se-Bi system are closely related to the precipitation of pure Bi2Se3 thermoelectric crystal phase. The optimal glass-ceramic composition is presented.

Spectroscopic studies of gamma irradiated Nd doped phosphate glasses

Ultra violet-visible (UV-Vis) and Fourier transform infrared (FT-IR) spectra of Nd doped phosphate glasses have been studied before and after gamma irradiation in order to understand the changes in the optical properties of glasses as well as to find the characteristics frequencies of the vibrational modes of chemical bonds, which decide the structural and spectral changes. UV, Vis, IR absorption and photoluminescence spectra of these glasses show changes depending on the composition of glass matrix. These changes are correlated on the basis of oxygen (O) and neodymium (Nd) concentration ratio obtained from energy dispersive X-ray spectroscopic (EDX) measurement. Gamma irradiation shows decrease in transmission below 700 nm for all the Nd 3+ absorption lines from all the samples. Differential absorption spectra (UV-vis) of the samples before and after gamma irradiation show generation of some new bands below 700 nm along with dips (decrease) in the spectrum at the location of main Nd 3+ absorption lines. This is attributed to the generation of different types of defects in the glass matrix along with possibility of change in the valence state of Nd 3+ to Nd 2+. IR absorption spectra of these glasses are found dominated mainly by the characteristics phosphate groups and water (OH) present in the glass network. The effects of gamma irradiation on IR absorption are observed in the form of bond breaking and possible re-arrangement of bonding. EDX and X-ray photoelectron spectroscopic (XPS) measurements indicate decrease in the relative concentration of oxygen in the glass samples after γ-irradiation.

Eruptive history and magmatic evolution of the 1.9 kyr Plinian dacitic Chiltepe Tephra from Apoyeque volcano in west-central Nicaragua

The youngest dacitic Plinian eruption in west-central Nicaragua, forming the 18 km3 Chiltepe Tephra (CT), occurred about nineteen hundred years ago at Apoyeque stratovolcano, which dominates the Chiltepe volcanic complex 15 km north of the capital Managua, where the CT is 2 m thick. We have traced the CT from its proximal facies at the crater rim, through the medial facies in the lowlands around Apoyeque, and to the distal facies up to 550 km offshore in the Pacific. While medial and distal facies consist of widespread Plinian fall deposits, the proximal facies reveals the complexity of this eruption, which we divide into four phases (I–IV). Interaction of rising magma with a pre-existing crater lake generated the phreatomagmatic opening phase I of the eruption, which produced ash fall with accretionary lapilli. Phase II marked a rapid change to persistent magmatic activity that yielded several large Plinian eruptions, declining through a period of unstable eruption conditions, followed by a short hiatus. Phase III began with unstable conditions, probably as a result of eastward migration and widening of the vent, leading to a second period of Plinian eruptions with three major events reaching magma discharge rates five times larger than those of phase II. Phase III again declined through unstable eruption conditions before magmatic activity terminated. Numerous explosions in the shallow hydrothermal system during the final phase IV resulted in the formation of a phreatic tuff ring on the rim of Apoyeque crater. The white, highly-vesicular, dacitic CT pumice contains plagioclase (An45–68), orthopyroxene, clinopyroxene, and minor hornblende, apatite and titanomagnetite phenocrysts. A very subordinate fraction of gray pumice has the highest crystal content, the least evolved bulk-rock, but the most evolved matrix-glass composition. The CT dacite has two unusual compositional features: (1) all white dacite has the same melt (matrix-glass) composition such that variations in bulk-rock compositions (64–68 wt% SiO2) simply reflect different phenocryst contents of 10–35%, interpreted as the result of gradual phenocryst settling in the magma chamber. (2) Abundant olivine crystals with a bimodal distribution in Mg# (modes at Mg# = 0.75 and Mg# = 0.8) are dispersed throughout the erupted dacite. These are clearly out of equilibrium with the dacitic melt and are interpreted as xenocrysts derived from the basaltic Nejapa-Miraflores volcanic lineament that intersects the Chiltepe volcanic complex and was contemporaneously active. Thermobarometric estimates place the dacitic CT magma reservoir in the upper crust (<250 MPa), with a temperature of about 890°C and about 5 wt% water dissolved in the melt. Comparing water and chlorine contents with respective solubility models suggests that volatile degassing began in the magma reservoir and triggered the CT eruption. From the vertical compositional variation pattern of the CT we deduce that the conduit tapped the magma chamber not at the top but from the side, at some deeper level, and that subsequent magma withdrawal was governed by both variations in discharge rate and possible upward migration and/or widening of the conduit entrance.

中国古代玻璃的拉曼光谱及质子激发X射线荧光发射无损鉴定

Nondestructive Raman spectroscopy and external-beam proton-induced X-ray emission (PIXE) technique to analyze eight ancient glasses unearthed from the provinces of Henan, Hubei, and Jiangsu, which allowes for a good characterization of the glass matrix and chemical compositions, is carried out. The results indicate that all the eight glass samples could be typically divided into three systems: faience (sample No. SZWG-4), PbO-BaO-SiO2 (sample Nos. NYWKI-5-1, HNWKII-88, and HNWKII-84), and Na2OCaO-SiO2 (sample Nos. HBWKI-16, HBWKI-17, HBWKI-18, and SZWG-1). Additional relationships between the Raman spectra and parameters, such as residues of raw materials and opacifying agent, are also discussed by respectively comparing them with similar glass samples excavated from other historical sites.

Growth and Characterization of Novel System of Nanoparticles Embedded in Phosphate Glass Matrix

We present a study of growth of a novel system of CdTe nanoparticles embedded in sodium/lithium-mixed phosphate glass matrix in a strong quantum confinement regime. The prepared systems are characterized by differential thermal analysis, X-ray diffraction, TEM, optical absorption, infrared and Raman Spectroscopy. We have investigated the effect of glass matrix composition and annealing time on the growing of the CdTe semiconductor nanoparticles. We found that the decrease in Na2O content and addition of ZnO to the glass composition is strongly affecting the nanoparticles formation and capping surface of the nanoparticls. On the other hand, we have calculated the size of nanoparticles by effective mass approximation (EMA) and empirical method based on tight binding approximation and found that the calculation based on tight binding approximation are very plausible than that one calculated by EMA.

Luminescence behaviors of the Eu 2+ ions in the GeS 2-Ga 2S 3-CsCl chalcohalide glasses

In the paper, we report the luminescence behaviors of Eu 2+-doped chalcohalide glasses. Composition of glass matrix is 37.5GeS 2-22.5Ga 2S 3-40CsCl (mol%) with the concentration of Eu 2+ in the range of 0.1–0.25 (mol%). The optimal Eu 2+ doping concentration was 0.15 mol% at which the glass exhibited an enhanced emission peaking at 434 nm with a full width at half maximum (FWHM) about 80 nm with the excitation at 395 nm.

Vesiculation and Microlite Crystallization Induced by Decompression: a Case Study of the 1991–1995 Mt Unzen Eruption (Japan)

Isothermal decompression experiments were performed to simulate magma ascent at Unzen volcano from the depths of magma storage to shallow crustal levels, corresponding to pressure decrease from 300 to 50MPa. A partially crystallized synthetic rhyodacitic magma (representing equilibrium conditions at 8508C and 300MPa) was used as a starting material; this has a composition identical to the groundmass of Unzen rocks erupted in 1991^1995. Decompression rates were varied from 0·0002 to 20MPa s . Experiments conducted with decompression rates 0·1MPa s 1 were decompressed continuously; a multi-step decompression approach was used at decompression rates 0·1MPa s . The experiments were fluid-saturated, either containing only water as a fluid component (H2O-bearing) or containing a water and carbon dioxide mixture (H2OþCO2; initial mole fraction of H2O in the fluid 0·6).The experimental products of the H2O-bearing experiments consist of amphibole, pyroxenes, oxides and glass. Plagioclase microlites nucleated and grew only in experiments with the two lowest decompression rates of 0·0005 and 0·0002MPa s . The length of those plagioclases is up to 200^250 mm, which is consistent with the size of plagioclase microlites observed in the natural samples.The experimental products of the H2OþCO2-bearing system are composed of pyroxenes, oxides, glass and plagioclase. Plagioclase microlites in the H2OþCO2-system were already present in the starting assemblage and grew to a maximum size of 80 mm. Equilibrium concentrations of water in the residual glasses at the final pressure of 50MPa are reached at decompression rates 1MPa s 1 for the H2OþCO2-bearing system and 0·1MPa s 1 for the H2O-bearing system. The bubble number density (BND) values range from 10 to 10 mm 3 in the H2O-bearing system and from 10 4·6 to 10 mm 3 in the H2OþCO2-bearing systems. In both systems, BND values decrease with decreasing decompression rate from 20 to 0·01MPa s , and increase with decreasing decompression rates50·01MPa s , which is interpreted to reflect predominant bubble growth and bubble nucleation, respectively.The onset of crystallization, observed from changes in the chemical composition of the residual melt, occurs at decompression rates 50·1MPa s . At the lowest decompression rate (0·0002MPa s ) the chemical composition of the residual melt in the H2OþCO2-bearing system becomes similar to the natural matrix glass composition. There is no significant variation of the microlite number density (MND) value as a function of the decompression rate. The MND values for plagioclases-only range from 10 to 10 mm , whereas the MND values for the other phases range from 10 to 10 mm . Our experimental MNDPl values are in the range of those from natural samples (10^10 mm ).We show that the size of microlites nucleating and crystallizing during decompression (plagioclase in our experimental dataset) is useful to constrain magma ascent rates at the onset of the crystallization of the corresponding phase. Based on the size of plagioclase microlites and on the composition of the residual melts, the average magma ascent rates of Unzen magmas in the pressure range 200 to 50MPa is estimated to be 10^50 m h .

A melt inclusion study of the Toba Tuffs, Sumatra, Indonesia

The Toba Caldera in Northern Sumatra, Indonesia is the site of Earth's largest Quaternary volcanic eruption. This eruption, dated at 74 ka, produced the 2800 km 3 Youngest Toba Tuff (YTT) and ash-fall. Quartz-bearing silicic pumices ranging from 68 to 77 wt.% SiO 2 indicate that the YTT magma was zoned compositionally and mineralogically. Prior to the YTT eruption, two other silicic quartz-bearing tuffs known as the Middle Toba Tuff (MTT) and the Oldest Toba Tuff (OTT) were erupted from Toba at 0.501 Ma and 0.840 Ma respectively. Although the volatile contents of the Toba magmas are poorly constrained, aerosols generated by the YTT eruption are generally thought to have caused a global volcanic winter. An evaluation of the pre-eruptive dissolved gas contents of the YTT magma is fundamental to understanding the global effects of this eruption. We used melt inclusions in quartz crystals to determine the dissolved H 2O, CO 2, S, Cl, and F contents of the YTT, MTT, and OTT magmas. Quartz crystals selected from pumice blocks and welded tuffs that spanned the compositional ranges of the three units were chosen for study. Major and trace element analyses of melt inclusions were also conducted to characterize melt evolution and provide context to the volatile data. Melt inclusions from the YTT, MTT, and OTT are rhyolitic in composition (73–77 wt.% SiO 2) and have overlapping, indistinguishable major element trends. Inclusions from the large eruptions (YTT and OTT) have similar geochemical relationships where the most evolved melt inclusions occur in the least silicic bulk rock samples and are more evolved than their matrix glasses. In contrast, the least evolved melt inclusions occur in the most silicic samples and either overlap with, or are less evolved than their matrix glasses. These patterns can be explained if quartz crystals in the least silicic magmas were inherited from more evolved melt, while those in the most silicic melt formed in-situ. Several lines of evidence suggest that crystal settling of early-formed quartz crystals in long-lived magma bodies was an important process in the YTT and OTT magmas. Trace element data from the YTT melt inclusions have wide ranges (Rb = 250–830 ppm, Ba = < 10–485 ppm) and mostly support these models; however, incompatible trace elements are enriched 2–3× over their matrix glass compositions in all samples. In the smaller MTT, melt inclusions overlapped with the compositional range of the bulk rock samples and are consistent with in-situ crystallization. FTIR analyses indicate that the YTT, MTT, and OTT melts contained about 4.0–5.5, 2.0–5.5, and 2.0–5.5 wt.% H 2O respectively. CO 2 contents in all units are generally < 100 ppm and Cl is < 2000 ppm. Water gradients occur in all 3 tuffs, Cl gradients are evident only in the YTT, and the least silicic samples from all units had no detectable CO 2. Sulfur contents in melt inclusions are low in all samples (< 32 ppm) and overlap with matrix glass S contents. Applying broad degassing constraints, about 10 14 g of H 2SO 4 aerosols were likely loaded into the atmosphere during the YTT eruption, 2 orders of magnitude less than previous petrologic estimates. Considerably more Cl and F, about 10 15 g of each, may have been part of the YTT aerosol cloud.

Crystallization Behavior of a New Transparent Glass-Ceramics

In this article we present a new kind of large grain transparent glass-ceramics obtained by the method of crystal growth from a homogenous glass, the simultaneous variation of the glass matrix and crystalline compositions during the crystallization results in the high transparency of this kind of large grain, high crystalline volume glass-ceramics, which have suitable refractive indexes between respective phases. The nucleation and crystallization behaviors of this kind of glass-ceramics have been investigated. The optimum heat treatment schedule for the glass was determined by means of DSC, XRD and SEM. The desirable optical property, such as laser characteristics etc, of this new kind of glass-ceramics can be further developed by doping with transition metals or rare-earths.

Afterglow luminance property of phosphorescent phosphor SrAl2O4:Eu2+,Dy3+-glass composites

The effect of mixing ratio, firing temperature and matrix glass composition on afterglow luminance property of SrAl 2 O 4 : Eu 2+ ,Dy 3+ -glass composites were investigated. As a result, the brightness showed a maximum at 35 mass % of the mixing ratio of the phosphor for the glass and 780°C of the firing temperature. And it was increased with decreasing the Na 2 O content of the matrix glass. From the backscattered electron and the EDX analysis, it is thought that the intermediate layers generated between the phosphors and the Na 2 O-poor matrix glass work as antireflective and the phosphor particles in the composite emit phosphorescent light more efficiently. As higher the basicity parameter, B, the intermediate layer was clearer, which means that the reactivity at the phosphor/glass boundaries was lower, and the narrow reaction layers was formed.

Conditions of Magma Storage, Degassing and Ascent at Stromboli: New Insights into the Volcano Plumbing System with Inferences on the Eruptive Dynamics

Stromboli is known for its persistent degassing and rhythmic strombolian activity occasionally punctuated by paroxysmal eruptions. The basaltic pumice and scoria emitted during paroxysms and strombolian activity, respectively, differ in their textures, crystal contents and glass matrix compositions, which testify to distinct conditions of crystallization, degassing and magma ascent. We present here an extensive dataset on major elements and volatiles (CO2, H2O, S and Cl) in olivine-hosted melt inclusions and embayments from pyroclasts emplaced during explosive eruptions of variable magnitude. Magma saturation pressures were assessed from the dissolved amounts of H2 Oa nd CO2 taking into account the melt composition evolution. Both pressures and melt inclusion compositions indicate that (1) Ca-basaltic melts entrapped in high-Mg olivines (Fo89^90) generate Stromboli basalts through crystal fractionation, and (2) the Stromboli plumbing system can be imaged as a succession of magma ponding zones connected by dikes. The 7^10 km interval, where magmas are stored and differentiate, is periodically recharged by new magma batches, possibly ranging from Ca-basalts to basalts, with a CO2-rich gas phase.These deep recharges promote the formation of bubbly basalt blobs, which are able to intrude the shallow plumbing system (2^4 km), where CO2 gas fluxing enhances H2O loss, crystallization and generation of crystal-rich, dense, degassed magma. Chlorine partitioning into the H2O^CO2-bearing gas phase accounts for its efficient degassing (� 69%) under the open-system conditions of strombolian activity. Paroxysms, however, are generated through predominantly closed-system ascent of basaltic magma batches from the deep storage zone. In this situation crystallization is negligible and sulfur exsolution starts at � 170 MPa. Chlorine remains dissolved in the melt until lower pressures, only 16% being lost upon eruption. Finally, we propose a continuum in explosive eruption energy, from strombolian activity to large paroxysmal events, ultimately controlled by variable pressurization of the deep feeding system associated with magma and gas recharges.