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Glasses and glass-ceramics were prepared by melting municipal solid waste (MSW) incinerator fly ash and their corrosion properties were evaluated. Corrosion of both materials proceeded in two different steps. At the initial stage, the corrosion process is a diffusion-controlled process. After approximately 10 h at the initial stage, weight losses increased linearly with time due to the total dissolution of glasses or glass-ceramics. Leaching of heavy metals from glasses and glass-ceramics were well within international environmental regulations. Corrosion proceeded uniformly in fly ash glass while Na2CaSiO4 crystalline phase was preferentially dissolved in the glass-ceramics.

Fly ash from municipal solid wastes (MSW) incinerators in Korea contains a large amount of toxic materials and requires pertinent treatments. However, since fly ash in Korea has a high chlorine concentration, it is difficult to apply cementation and chemical treatment techniques. In this study, we report the vitrification of fly ash along with the properties of the glasses and leaching characteristics of heavy metal ions. Fly ash can be vitrified by melting at 1500 degrees C for 30 min with the addition of >5 wt.% of SiO2. Glasses showed Vickers hardness of 4000-5000 MPa, bending strength of 60-90 MPa and indentation fracture toughness of approximately 0.9 MPa m(1/2). Glasses also showed the excellent resistance against leaching of heavy metal ions with Cd2+ <0.04 ppm, Cr3+ <0.02 ppm, Cu2+ <0.04 ppm and Pb2+ <0.2 ppm. These results indicate that the vitrification technique is effective for the stabilization and recycling of toxic incinerator fly ash.

We report on the elastic properties of xMnO‐Al2O3‐(6‐x)SiO2 manganese aluminosilicate glasses, in which pronounced exchange coupling and antiferromagnetic interaction occurs among the paramagnetic Mn2+ ions. X‐ray absorption reveals a Mn‐O bond length of ∼2.1 Å, and a distance of ∼3 Å between Mn2+ ions in sixfold coordination, further corroborated by electron paramagnetic resonance and dynamic photoluminescence spectroscopy. This indicates the presence of edge‐sharing MnO6 units, in resemblance to edge‐sharing MnO8 in the crystalline Spessartine garnet Mn3Al2[SiO4]3. We argue that these cluster species have a profound effect on material stiffness: the compact structure of manganese aluminosilicate glasses enables a Young's modulus in the 100 GPa range and a Poisson's ratio of about 0.3. This exceeds the compositional trend with cation field strength observed for other aluminosilicate glasses. [ABSTRACT FROM AUTHOR]

Core‐shell structure in Cd‐Zn‐Se quantum dots (QDs) precipitated in the silicate glass matrix by continuous wave laser (λ = 532 nm) were demonstrated using transmission electron microscopy (TEM) and local electrode atom probe (LEAP) tomography. TEM images of the QDs in glasses after 60 min of irradiation at 9 W/cm2 show two portions with different contrasts, and diameters of 5.97 and 22.49 nm, respectively; 3D elemental distribution in these glasses from LEAP tomography shows areas of high Zn concentration near the CdSe QDs. Iso‐concentration images obtained using visualization software show that Cd‐rich clusters were not completely covered by the Zn‐rich shells in the glass after 15 min irradiation that resulted emission due to the surface defects of CdSe QDs. As the irradiation time increased to 60 min, the Zn‐rich cluster gradually surrounded the Cd‐rich core to form shells that eliminated the surface defects. During laser irradiation, CdSe QDs precipitated first due to the high degree of supersaturation of Cd and Se followed by the sequential incorporation of Zn on the Cd‐rich QDs forming shells. [ABSTRACT FROM AUTHOR]

Continuous‐wave laser (λ = 532 nm) was irradiated on Ag+‐exchanged glass surfaces to precipitate PbS quantum dots (QDs) of various diameters. TEM images combined with element mapping results confirmed the formation and size distribution of PbS QDs. Photoluminescence spectra red‐shifted from 1336 nm to 1635 nm with increases in power density and duration of laser irradiation. Three representative irradiation conditions are proposed to realize broadband photoluminescence from one glass rod to cover the 1.3‐1.7 μm communication window. [ABSTRACT FROM AUTHOR]

CdSe QDs with Cd1−xZnxSe shell structures were precipitated inside silicate glasses by continuous‐wave laser irradiation (λ = 532 nm) without any heat‐treatment process. Emission from the surface defects (λ ≈ 620 nm) was quenched significantly and the lifetimes of the band‐edge emission was increased. During the laser irradiation, Zn ions were gradually incorporated into the outer region of CdSe QDs to form Cd1−xZnxSe (0.76 ≤ x ≤ 0.8) alloy shells. [ABSTRACT FROM AUTHOR]

Heavy metal oxide glasses containing GeO[SUB2] were investigated as potential hosts for 1.48 μm fiber-optic amplifiers because of their low phonon energy. Addition of &ges; 10 mol % GeO[SUB2] to 0.57PbO-0.25Bi[SUB2]O[SUB3] - 0.18Ga[SUB2]O[SUB3] (mole fraction) glass provided thermal stability as well as good emission properties. The optimum glass composition for 1.48 mm amplifiers, considering lifetimes and population of the Tm[SUB3+]:[SUP3]H[SUB4] level, was 0.8 (0.57PbO-0.25Bi[SUB2]O[SUB3] - (0.18Ga[SUB2]O[SUB3] - 0.2GeO[SUB2] (mole fraction). As the concentration of codoped Ho[SUP3+] exceeded 0.2 mol %, the population density of the Tm[SUP3+]:[SUP3]H[SUB4] level decreased sharply and the population inversion between the [SUP3]H[SUB4] and [SUP3]F[SUB4] levels in Tm[SUP3+] was achieved. [ABSTRACT FROM AUTHOR]

Low-temperature midinfrared emission properties of Pr[sup 3+]-doped Ge[sub 30]Ga[sub 2]As[sub 6]S[sub 62] and Ge[sub 28]Ga[sub 5]As[sub 12]Se[sub 55] glasses (at. %) were investigated. Emissions centered at 3400 and 4700 nm were clearly observed from sulfide and selenide glasses, respectively, when the specimens were cooled to 20 K. The measured lifetime of the [sup 1]G[sub 4] level in sulfide glass increased from 320 μs at room temperature to 400 μs at 20 K. The intensity and quantum efficiency of the emission from the Pr[sup 3+]:([sup 3]F[sub 3], [sup 3]F[sub 4]) level in selenide glass also increased as the temperature decreased to 120 K. The enhancement resulted from a decrease in nonradiative multiphonon relaxation at low temperatures. The temperature dependence of the multiphonon relaxation rates indicated that the asymmetrical stretching vibration of GeS[sub 4] tetrahedra (375 cm-1) is primarily responsible for the multiphonon relaxation process in sulfide glass. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Spectroscopic properties and room-temperature persistent spectral hole burning mechanisms of Eu[sup 3+] -doped borate glasses were investigated. The depth of the burnt hole increased K. The photoreduction of Eu[sup 3+] to Eu[sup 2+] is a primary mechanism of hole burning and this hypothesis was supported by spectral hole properties, relaxation properties as well as changes in the local structure of Eu[sup 3+] in glasses. [ABSTRACT FROM AUTHOR]

Quantum dot embedded glasses (QDEGs) were prepared by the conventional melt‐quenching method to enhance its color conversion efficiency via optimizing the concentration of ZnS, ZnSe, and CdO within the silicate‐based glass matrix. The QDEG, which contained 0.875 ZnS, 0.625 ZnSe, and 0.75 CdO (in mol%) and was heat treated at 500°C for 10 hours showed promising color conversion with an improved quantum yield of up to 25%. Color coordination of light‐emitting diodes (LEDs) mounted with the QDEGs could be adjusted by tuning heat‐treatment conditions and thickness control of QDEGs. The practical feasibility of the QDEG for a white LED is demonstrated with a reasonable glass thickness for LED packaging process. The formation of Cd‐S‐Se quantum dots within a glass matrix was identified by Raman and HR‐TEM analyses. The effect of ZnSe and CdO on the formation of Cd‐S‐Se quantum dots within silicate glass is also discussed. [ABSTRACT FROM AUTHOR]

Abstract: Fluorescence intensity ratios (FIRs) of the 640 nm and 602 nm emissions from Sm3+ were recorded at various temperatures T to identify the temperature increases ΔT associated with laser‐induced local heating of Ag nanoparticles. The FIRs increased as intensities of the excitation beam from a 532‐nm continuous‐wave laser increased. Estimated T of the irradiated region increased to as high as 586°C when at laser irradiation of 1.5 W on the surface containing Ag nanoparticles. Local heating due to the surface plasmon resonance of Ag nanoparticles is a main reason for the ΔT that eventually leads to precipitation of PbS quantum dots in glasses. [ABSTRACT FROM AUTHOR]

A low sintering temperature glass based on the SiO2-P2O5-ZnO-B2O3-R2O (R=K and Na) system was studied as a matrix for embedding phosphors to fabricate color tunable white LEDs. The proposed system, which uses no heavy-metal elements and can be sintered at 500°C, incorporates thermally weak commercial phosphors such as CaAlSiN3:Eu2+ to produce phosphor-in-glasses (PiGs). Changing the mixing ratio of glass to phosphors affected the photo-luminescence spectra and color coordinates of the PiGs when mounted on a blue LED. The color rendering index (CRI) and color correlated temperature (CCT) of the LEDs were also varied with the mixing ratio, providing color tunable white LEDs. A high CRI, up to 93, as well as highly improved thermal stability were obtained, along with a low sintering temperature compared to other glass systems, suggesting the practical feasibility of the proposed system. [ABSTRACT FROM AUTHOR]

The influence of Nd2O3 addition on the precipitation kinetics of lead chalcogenide (PbS) quantum dots ( QDs) in silicate glasses was investigated. Energy dispersive X-ray spectroscopy ( EDS) indicated that the Nd3+ ions are preferentially located inside the PbS QDs rather than in the glass matrix. Changes in diameter ( D) of PbS QDs exhibited smaller time dependencies (i.e., D≈ t0.270-0.286) than that predicted by the classical Lifshitz-Slyozov-Wagner ( LSW) theory. This is due to the limited concentrations of Pb2+ and S2− ions and the large diffusion distance inside the glass matrix. In addition, extended X-ray absorption fine structure ( EXAFS) results indicated that the formation of PbS QDs was retarded due to the presence of Nd2O3 in the glasses, as the large NdO x polyhedra interrupt the diffusion of Pb2+ and S2− ions. We believe that these Nd3+ ions are primarily located in PbS QDs in the form of Nd-O clusters, and that the PbS QDs are built on top of these clusters. [ABSTRACT FROM AUTHOR]

Fluorescent glass frits were prepared and used to synthesize phosphor-in-fluorescent glass composites (PiFGs) to realize stable white light emitting diodes with high color-rendering properties. Commercial red, green, and blue phosphors were co-sintered and red phosphors were partially replaced by Eu3+ in glass frits. Phosphor-in-glass composites were placed on UV-light emitting diodes ( UV- LEDs) to generate white light. Pure white light with a luminous efficacy=58.4 lm/W, general color rendering index Ra=87 and special color rendering index for strong red R9=73 was realized with glass frits containing 7 mol% Eu2O3 and RGB ratio of 35:20:15. Luminous efficacy, Ra and R9 increased as red phosphors were replaced by red-fluorescent glass frits. [ABSTRACT FROM AUTHOR]

Modulation of the band gap energy and diameter of quantum dots (QDs) formed in glasses is important to achieve the optimized performance for applications as infrared light sources, lasers, saturable absorbers, etc. Absorption and photoluminescence of PbS QDs were extended into mid-infrared wavelength range in glasses containing small amount of lead but oversaturated with sulfur. Dual-band photoluminescence of PbSe QDs was prepared in oxyfluoride glass-ceramics containing BaF2 nanocrystals. By introducing SnO in the glasses, alloyed Pb1-xSnxSe QDs with smaller band gap energies were formed in glasses, and mid-infrared photoluminescence of Pb1-xSnxSe QDs at ~2570 nm in wavelength was achieved. [ABSTRACT FROM AUTHOR]

Abstract: Precipitation of PbS quantum dots (QDs) in silicate glasses controlled by Ag+ ion diffusion was investigated. Ag+ ions penetrated ~0.5μm into the glass when the glass was immersed in the AgNO3 solution at 80°C. Ag nano-particles (NPs) and PbS QDs were formed after heat-treatment at temperatures of 420–460°C for 10h. PbS QDs in Ag+-diffused regions photoluminesced at longer wavelengths than did those in Ag+-free regions. This indicates that PbS QDs thus formed in regions containing Ag NPs were larger than those in Ag+-free regions and this size difference was confirmed from the transmission electron microscope images. PbS QDs can grow at temperature as low as 420°C in Ag+-diffused regions and this implies that PbS QDs form preferentially using Ag NPs as nucleating agents. [Copyright &y& Elsevier]

Silicate glasses containing CdS and Ag2O were made by the melt-quenching method. CdS quantum dots ( QDs) were precipitated inside the glass matrix by heat treatment at 570-590 °C for 10 h, and the influence of Ag on photoluminescence ( PL) of CdS QDs was investigated. The emission located at 478-493 nm in wavelength originated from the direct recombination of electron/hole pairs was quenched due to charger transfer between Ag and CdS QDs. Modification of PL from CdS QDs by Ag provides potentials toward developing the color changing materials for light-emitting diodes ( LEDs). [ABSTRACT FROM AUTHOR]

Abstract: Transparent nano-crystalline glass–ceramics (nano-structured glasses) were prepared from oxy-fluoride precursor glass doped with HoF3 and their luminescence properties were investigated. Visible blue, green and red emissions were observed, and the relative intensity of the green and red emission was strongly dependent on HoF3 concentration. Under 750 nm pumping, the intense green emission due to the photon avalanche process was observed at room temperature from nano-structured glass doped with high (0.5mol%) concentration of HoF3. [Copyright &y& Elsevier]

Emission characteristics and energy transfer in chalcohalide glasses doped with Tm3+ and Tb3+ were investigated and their potential as S-band fiber-optic amplifiers was evaluated. Upon the addition of CsBr into sulfide glass, intensity of the 1.48 μm emission (3H4 → 3F4 transition) from Tm3+ increased. At the same time, the lifetime of the 3H4 level increased to 1.2 ms, approximately eight times longer than the value obtained from sulfide glass. Quantum efficiency of the transition also increased to approximately 90%. Cross relaxation between the 3H4 and 3F4 levels was significant when Tm3+ ion concentration exceeded 0.2 mol%. Population density of the 3F4 level in Tm3+ decreased upon the addition of Tb3+ due to the Tm3+:3F4 → Tb3+:7F0,1,2 energy transfer. Population inversion became possible when Tb3+ concentration reached 0.11 mol%. [Copyright &y& Elsevier]

Addition of CsBr and KBr into Eu3+-doped Ge–Ga–S glasses resulted in persistent spectral hole burning with high quantum efficiency, whereas the addition of alkali chloride did not show any evidence for a hole formation process. The characterization of the phonon side band spectra revealed the site for Eu3+ ions located near the Ga–Br− or Ga–Cl− units. The presence of Br− ions near Eu3+ lowers the energy of the conduction band, thereby enabling the interaction between the 4f electrons and the resultant conduction band. The interaction made the photo-reduction of Eu3+ to Eu2+ possible. However, the higher coupling of phonon energy with Eu3+ together with the higher electronegativity of Cl− ion in CsCl-containing glass compared to its CsBr counterpart, hindered the photo-reduction of Eu3+ into Eu2+. [Copyright &y& Elsevier]

Fluorescence and efficient persistent spectral hole burning of Eu3+ at 77 K were observed in chalcohalide glasses. The depth of the hole was approximately 30% after a burning process of 1 min with 50 mW power, and it was completely erased with Ar+ laser irradiation. The hole survived room temperature heat treatment and showed good thermal stability. The hole-burning mechanism was most probably the photo-reduction of Eu3+→Eu2+. Fluorescence from Eu3+ decreased with increasing temperature and disappeared at the temperature above ∼130 K. [Copyright &y& Elsevier]

Various rare earth (RE) oxides such as Pr 2 O 3 , Dy 2 O 3 , Ho 2 O 3 , and Er 2 O 3 were introduced into Cd–S–Se quantum dot embedded glasses (QDEGs) to investigate their effect on the color conversion properties of the Cd–S–Se QDEGs. The absorption and emission peak wavelengths due to the excitonic transition of the Cd–S–Se QDs were modified by the introduction of RE oxides, implying their influence on QD formation. The photoluminescence of the various QDEGs RE oxides under 450 nm excitation were monitored and compared with the un-doped QDEGs. White LEDs (wLEDs) were also fabricated with the RE-doped QDEGs and their color conversion properties, such as quantum yield (QY), luminous efficacy, correlated color temperature (CCT) and color rendering index (CRI) were examined. Transmission electron microscope (TEM) revealed that the size and spatial distribution of the QDs were improved by the RE-oxides. Their effect on QD formation within the silicate glass was discussed using Raman spectroscopy. • Cd–S–Se quantum dot embedded glasses (QDEG) with various rare earth (RE) ions were fabricated. • RE ions reduced QD size and modified spectral properties of QDEGs. • RE ions improved size and spatial distribution of QDs within glass matrix. • White LED was successfully achieved with RE-doped QDEGs. [ABSTRACT FROM AUTHOR]

1.6 μm emission originated from Pr[sup 3+]: ([sup 3]F[sub 3],[sup 3]F[sub 4])→[sup 3]H[sub 4] transition in Pr[sup 3+]- and Pr[sup 3+]/Er[sup 3+]-doped selenide glasses were investigated under an optical pump of a conventional 1480 nm laser diode. The measured peak wavelength and full width at half maximum of the fluorescent emission were ∼1650 and >100 nm, respectively. A moderate lifetime of the thermally coupled upper manifolds (∼212±5 μs) together with a high stimulated emission cross section of ∼(3±1)x10[sup -20] cm[sup 2] promises to be useful for 1.6 μm band fiber-optic amplifier that can be pumped with an existing high-power laser diode. Codoping of Er[sup 3+] significantly enhanced the emission intensity by way of a nonradiative Er[sup 3+]: [sup 4]I[sub 13/2]→Pr[sup 3+]: ([sup 3]F[sub 3],[sup 3]F[sub 4]) energy transfer. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Irradiation of x-rays has induced room-temperature persistent spectral hole burning (PSHB) in Eu[sup 3+]-doped borate glasses melted under an inert atmosphere. Defects were formed by x-ray irradiation and these defects, especially electron trapping centers near rare-earth ions in glasses, were responsible for the PSHB. Electrons were released from these defects upon irradiation of a burning light. Photoreduction of Eu[sup 3+] to Eu[sup 2+] by trapping these electrons resulted in the formation of persistent spectral holes. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: Optical properties of PbS quantum dots (QDs) precipitated inside the oxide glass matrix were investigated. Photoluminescence (PL) from the PbS QDs showed peak wavelengths located at 1170–1680nm with widths of 150–550nm. Radii of QDs in glasses were 2.3–4.7nm depending upon the thermal treatment. Peak wavelengths of PL bands shifted as much as 70nm as the temperatures and excitation irradiances increased. Calculated effective local temperatures indicated that these shifts of PL spectra were associated with local heating induced by the temperatures and laser beam. [Copyright &y& Elsevier]

Abstract: The local structure of Ge and Ga ions in (1− x)(Ge0.25Ga0.10S0.65)–xCsBr glasses (x =0.00,0.05,0.10 and 0.12) were investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy. CsBr formed [GaS3/2Br]− structural units in glass while Ge ions remained in GeS4/2 tetrahedra, unaffected by CsBr addition. Rare-earth ions can be surrounded by Br ions only when CsBr/Ga ratio in glass became larger than unity. [Copyright &y& Elsevier]

Different types of glasses and glass-ceramics were made using fly ash from sewage sludge incinerators. The optimum nucleation condition was heating at 760 °C for 1 h. Crystallization of the nucleated specimen in the region of 1050–1200 °C resulted in the formation of two crystalline phases, i.e. anorthite and diopside. The relative fractions of these two phases changed with crystallization temperature. Specimens heat-treated for 2 h at 1050 °C consisted mainly of diopside crystals with a minor proportion of anorthite. On the other hand, those heat-treated at 1150 °C were primarily composed of anorthite. Glass-ceramics containing large amounts of diopside (1050 °C/2 h) generally displayed better physical and chemical properties than their anorthite counterparts (1150 °C/3 h) due to the interlocking microstructure of diopside crystals. [Copyright &y& Elsevier]

An optimum glass composition for practical fiber fabrication was investigated for Ge–Ga–As–S–CsBr glasses. Dy3+ was doped into the glasses and its emission properties were examined. The best composition for practical use was 0.7[Ge0.25As0.1S0.65]–0.15GaS3/2–0.15CsBr. This glass also exhibited high resistance against the attack of liquid water. The lifetime and quantum efficiency of the 1.31 μm emission from Dy3+ increased approximately 17 and 4 times, respectively, compared to those obtained from other sulfide glasses. This is due to the formation of [GaS3/2Br]− units. The frequency of the effective phonon which dominates the multiphonon relaxation process decreased from 375 to 245 cm−1 with the addition of CsBr. [Copyright &y& Elsevier]

A new alkali-alumino tellurite glass composition was developed to immobilize highly-volatile technetium (Tc) wastes generated from the pyrochemical processing technology. Tellurite glass can incorporate up to 7 mass% of rhenium (Re, used as a surrogate for Tc) with an average retention of 86%. Normalized elemental releases evaluated by seven-day product consistency test (PCT) satisfied the immobilized low activity waste requirements of United States when concentration of Ca(ReO 4 ) 2 in the glass was <12 mass%. Re ions form Re 7+ and are coordinated with four oxygens to form ReO 4 − tetrahedra. These tetrahedra bond to modifiers such as Ca 2+ or Na + that are further connected to the tellurite glass network by Ca 2+ (or Na + ) – non-bridging oxygen bonds. [ABSTRACT FROM AUTHOR]

• Direct precipitation of CdS quantum dots in glass by ultrafast laser pulses is shown. • Size of CdS nanocrystals increases from periphery to center of laser-induced microdomains. • Laser-written domains exhibit polarization-sensitive optical properties. In this study, we investigated the structure of microdomains directly laser-written in the bulk of glass and containing CdS nanoparticles by transmission electron microscopy. The CdS nanocrystals have a multidisperse size distribution while quantum dots with a minimal size of ∼ 3–4 nm are registered near the edge of a microdomains. The size of CdS nanocrystals sweepingly increases up to ∼340 nm from the periphery to the center of the laser-written microdomain. It has been found that microdomains possess laser polarization-sensitive optical properties providing opportunities for the development of advanced optical data encoding and security tagging. [ABSTRACT FROM AUTHOR]

Abstract: This work presents a detailed study on near-infrared and mid-infrared fluorescence emissions with five sets of Tm3+-doped 75GeS2–15Ga2S3–10CsI chalcohalide glass. They are prepared in normal or water drying process. Based on the diffusion-limited relaxation calculation, a detailed investigation is put forward to obtain efficient near-infrared or mid-infrared fluorescence emissions of Tm3+ on the effect of H2O on the Tm3+ fluorescence. Detailed investigations are given to the interacted energy transferring processes between rare-earth, impurities and vibrating phonons with the appearance of fluorescence quenching, along with Tm3+, H2O concentrations varying and energy gaps forming. The radioactive properties are analyzed using compensated diffusion-limited relaxation calculation method, and the near-IR and mid-IR fluorescence properties are evaluated in detail with experimental and theoretical analysis. [Copyright &y& Elsevier]

Abstract: Spectroscopic properties of Tm3+ in (1− x) (Ge0.25Ga0.10S0.65)–xBr (or CsBr) glasses (x =0.0 and 0.1) were investigated. Emission properties of Tm3+ in 0.9(Ge0.25Ga0.10S0.65)–0.1Br glass were similar to those in Ge0.25Ga0.10S0.65 glass, while there was significant improvement when doped into 0.9(Ge0.25Ga0.10S0.65)–0.1CsBr glass. The lifetime of the Tm3+:3H4 level increased from 0.23 to 1.22msec with 10mol% CsBr addition. The presence of Cs+ facilitated the formation of [GaS3/2Br]− units by donating an electron to the Ga tetrahedron, resulting in the homogeneous distribution of Br. In this way, Tm3+ ions have their local environment made of Br only. When Br ions were added instead of CsBr, [GaS(4−x)/2Br]− units with x >1 were formed and Tm3+ ions were surrounded by both S and Br, producing a high phonon environment. [Copyright &y& Elsevier]

Abstract: From Dy L3-edge extended X-ray absorption fine structure spectroscopic analysis of Dy-doped Ge–As–S glass, we verified that both the coordination number and Dy–S distance are decreased in this representative chalcogenide glass compared to those in the Dy2S3 crystalline counterpart. The strong covalent nature inherent in chemical bonds between the constituent atoms of Ge–As–S glass would be responsible for the enhanced covalency of the Dy–S bonds, which would then be sensitively related to the optical characteristics of the 4f↔4f transitions of Dy3+ as well as the low rare-earth solubility exhibited by the Ge–As–S glass. [Copyright &y& Elsevier]

Abstract: Effects of CsI content on the optical properties of Ge30Ga5Sb5Se60 glasses were evaluated. Linear and non-linear absorption properties of the glasses without Pr3+ were examined in addition to 1.6μm emission properties of the Pr-doped glasses. Blueshift of the UV-side absorption edge was accompanied with increasing CsI concentration, while non-linear absorption coefficients measured at 1.06μm by the Z-scan method remained unaffected. Measured lifetimes of the 1.6μm emission from modified glasses were comparable to those of the unmodified glass. These experimental observations are discussed in connection with a pronounced weak absorption tail appeared in selenide glasses with the addition of CsI. [Copyright &y& Elsevier]

Abstract: The local structures around Tm3+ in Ge0.25Ga0.10S0.65 and 0.90 (Ge0.25Ga0.10S0.65)−0.10CsBr glasses were investigated using Extended X-ray absorption fine structure (EXAFS) spectroscopy. In Ge0.25Ga0.10S0.65 glass, Tm3+ ions are surrounded by approximately seven S ions. Addition of 10mol% CsBr resulted in significant changes in the EXAFS spectrum of Tm3+ ions due to the changes in the local structure surrounding Tm3+ ions. The first-nearest coordination shell around Tm3+ ion is predominantly composed of about six Br ions in 0.90 (Ge0.25Ga0.10S0.65)−0.10CsBr glass. [Copyright &y& Elsevier]

Abstract: The size and spatial distribution of PbS QDs in glasses need to be controlled in order to achieve desired optical characteristics. This paper reports on the use of several rare-earth oxides such as Ho2O3, Er2O3, and La2O3 to control the size of PbS QDs in silicate glasses. Additions of rare-earth oxides result in blue shifts of the absorption bands from 1344nm to 930nm, and the wavelengths of PL bands can be controlled between 1421nm and 1035nm. Additions of up to 0.8mol% of Ho2O3 decreased the diameters of PbS QDs from 4.82nm to 3.02nm. The same tendencies were found for both Er2O3 and La2O3 additions, although the size of PbS QDs increased as the ionic radius of rare-earth ions increased. It is proposed that clusters of RE–O bonds act as nucleating agents for the precipitation of PbS QDs. [Copyright &y& Elsevier]

Abstract: CdSe quantum dots (QDs) were precipitated in silicate glasses under various durations and temperatures of heat-treatment. Absorption and photoluminescence (PL) spectra of the QDs showed the quantum confinement effect from CdSe QDs. When the glass was heat-treated for 10h, estimated average QD sizes increased from 5.2nm when the glass was heat-treated at 490°C and to 6.9nm when it was treated at 500°C. When the glass was heat-treated at 480°C, estimated average QD sizes were 4.9nm after 20h and 5.3nm after 30h. The PL peak position was independent of the excitation wavelengths; this result indicates that the size distribution of CdSe QDs was narrow. [ABSTRACT FROM AUTHOR]