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The fracture mechanism of a chemically strengthened ultrathin glass (UTG) for the cover window of flexible display devices was investigated under pen loading conditions for the first time to better understand the UTG impact resistance characteristics. High‐speed camera analysis, fracture fragment analysis, and finite element modeling were employed to investigate the fracture mechanism of the UTG under pen drop conditions. A pen‐on‐plate (POP) test was also employed to examine the fracture characteristics under static loading condition, and its results were compared with those of the pen drop test (PDT) to find a correlation between the static and dynamic loading conditions. The correlation found between the POP and PDT tests indicates that a quantitative estimation of contact displacement under PDT can be obtained by measuring the first ring crack size, to more easily determine the impact resistance characteristics of UTG. [ABSTRACT FROM AUTHOR]

Transparent γ-AlON undoped and doped with one of eight rare earth elements were fabricated by hot pressing at 1850 °C. After characterizing the fundamental physical properties of sintered γ-AlON, the photoluminescence spectra of γ-AlON:Sm and γ-AlON:Yb were examined further because only these samples showed a color under visible light because of the absorbance of a certain wavelength. γ-AlON:Sm exhibited a red emission with emission peaks at 688, 701, and 729 nm, while γ-AlON:Yb exhibited a white emission due to the two broad emission peaks at 438 and 575 nm. γ-AlON:Yb revealed a possible application to UV-excited phosphor-converted white-light-emitting diodes because of its emission characteristics. The schematic crystal structure of the rare-earth-doped γ-AlON and the CIE chromaticity diagram were provided to understand the photoluminescence behavior of γ-AlON:Sm and γ-AlON:Yb. [ABSTRACT FROM AUTHOR]

SiO2‐Na2O‐Al2O3‐LaF3 glass‐ceramics doped with Eu2+ were synthesized as an efficient inorganic color converter for 400 nm UV‐LED. When Eu2+ formed within the glass matrix, the obtained glass showed cyan emission under 400 nm excitation, but its emission peak drastically shifted to greenish yellow upon heat treatment. With heat treatment the glass‐ceramic also showed highly increased emission intensity, and the color coordinate of the glass‐ceramic shifted to yellow. When it was mounted on top of a 400 nm UV‐LED, it demonstrated high color conversion efficiency and practical feasibility as an UV‐LED color converter. To vary the color coordination the heat‐treatment conditions and the thickness of the glass‐ceramic were adjusted. The resulting ceramic showed a high quantum yield of up to 78%, which is comparable to conventional ceramic phosphors. The spectral change in the glass‐ceramic is attributed to the formation of nepheline and LaF3 crystalline phases. X‐ray diffractometer (XRD), transmission electron microscope with energy dispervise spectroscopy (TEM‐EDS) and cathode luminescence (CL) were used to investigate the mechanism of Eu2+‐doped nepheline crystal formation, and its effect on the spectral change with heat treatment. [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]

Efficient persistent spectral hole burning in Eu[sup 3+]-doped sulfide glasses was observed with the addition of CsBr or KBr. Holes in these glasses showed high initial growth rates, thermal barrier heights, and low relaxation rates. It was also possible to form independent multiholes on the inhomogeneously broadened absorption spectrum. One-photon absorption of the burning light and corresponding reduction of Eu[sup 3+] into Eu[sup 2+] via interaction with local conduction (or charge transfer) bands are the main processes for hole burning. [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]

A complete inorganic quantum dot color converter for a white LED is achieved using silicate-based quantum-dot-embedded glasses (QDEGs). The white LED exhibits a high CRI of 90 and highly improved thermal stability up to 200 °C, demonstrating its robustness and practicality. The CdSe/CdS core/shell structure within the silicate glass is expected to enhance the colour converting efficiency. [ABSTRACT FROM AUTHOR]

Commercial Ce3+: YAG phosphors were embedded in glass frits. Thermal condition for the viscous sintering of the composite materials was optimized. The phosphor-glass composites had maximum external efficiency of 30% and maximum light extraction efficiency of 39%. Color temperatures of the composites composed of fluorescent glass frits containing Eu3+ and Mn2+ combined with blue LEDs shifted from ~7000 to ~4000 K. [ABSTRACT FROM AUTHOR]

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: The 1.4μm emission properties of Tm3+ ions embedded in tellurite glass containing MoO3 have been investigated in an effort to develop non-crystalline materials for ultra broadband optical amplifier. Spectral lineshape and bandwidth of the 1.4μm emission exhibited a negligible dependence on amount of MoO3, while the measured lifetime of the Tm3+:3H4 state decreased with increase in MoO3 content. Multiphonon relaxation turned out to become stronger with increase in MoO3 amount, which coincided with the further broadened Raman scattering bandwidth of the MoO3-containing tellurite glass. The spectroscopic properties of Tm3+ ions doped in our modified tellurite glasses are discussed in connection with the local structural parameters obtained from Tm L 3-edge EXAFS analysis. [ABSTRACT FROM AUTHOR]

Abstract: Glasses with a P2O5–SnO–MnO ternary system were synthesized and characterized. Glass forming range was determined to be 5–20mol% of MnO when the content of SnO was kept below 50mol%. Various analyses including thermal, optical and structural characterization were performed on (85− x)P2O5–xSnO–15MnO (x =30, 35, 40 and 45 in mol%) and (55− y)P2O5–45SnO–yMnO (y =0, 5, 10 and 15 in mol%) glasses in order to investigate the compositional effect of SnO and MnO on the properties of glass. Glass transition temperature of all the prepared glass samples turned out to be below 350°C, but showed a compositional dependency on SnO and MnO, which was discussed in terms of the structural changes derived from Raman spectroscopy. The visible transparency of both glass series was identified with their high optical bandgap of 3.4–3.7eV and their refractive indices varied between 1.6 and 1.9 depending on the wavelength monitored and composition. Er3+ doped the glasses to examine their potential as a photonic gain medium. Radiative emission properties, Judd–Ofelt analysis and stimulated emission cross-sections also exhibited the influence of SnO and MnO and suggested the preferred concentrations of SnO and MnO as 35mol% and 5mol%, respectively. Modification of the local structure around the Er3+-ion upon the compositional variation was responsible for the phenomena. This is also discussed with the structural contribution of SnO and MnO. [ABSTRACT FROM AUTHOR]

Glass-forming range and electrical conduction properties of V2O5–P2O5–WO3 ternary system were investigated. The glass-forming ability of this system was quite good within a wide compositional area where the P2O5 content ranges from 20 to 80 mol%. This glass exhibited a high dc-conductivity up to 6.71 × 10−4Ω/cm at 473 K. The variation of conductivity (log(σ T)) of the glass with temperature (1/ T) exhibited a linear relationship, which suggests electrical conduction through the small polaron hopping above room temperature. Compositional effect on the conductivity was studied upon varying WO3 and P2O5 concentration. Substitution of V2O5 with P2O5 resulted in a decrease of the conductivity with the increase of activation energy, while substitution of WO3 showed relatively little effect on the activation energy. Structural modification along with the valence state change of vanadium and tungsten ions were discussed in connection with Raman spectroscopy and X-ray photoelectron spectroscopy analysis. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the fluorescence lifetimes of Dy3+: 1.3μm emission in the chalcogenide Ge–As–S glasses with different compositions but identically containing 0.5mol%Ga and 0.5mol% CsBr. The measured lifetimes turn out to be sensitive not only to the concentrations of Ga and CsBr but also to compositional variations in the Ge–As–S host glasses. The lifetime is enhanced conspicuously in glass of the S-sufficient compositions, relative to the stoichiometric GeS2–As2S3 composition, while this effect is not significant in the S-exact and S-deficient compositions. We employ GaK-edge EXAFS analysis to support that the local structural environments of Ga in the modified chalcogenide glasses are closely correlated with the lifetime enhancement effect. [Copyright &y& Elsevier]

Pr3+ singly doped SiO 2 –Na 2 O–Al 2 O 3 –LaF 3 glass ceramics were fabricated as an inorganic color converter with wide color gamut for white light emitting diodes (wLEDs). Under 450 nm LED excitation, the simultaneous photo-luminescence (PL) emissions of green at 502 nm due to the Pr3+:3P 1 →3H 4 transition and red at 613 and 643 nm due to Pr3+:3P 0 →3H 6 and 3P 0 →3F 2 , respectively, were observed. Before heat treatment, the PL intensity of the green and red emissions were limited relative to that of the blue electroluminescence (EL), due to the high transparency of the glass. This was highly improved by the crystallization of the glass with heat treatment. PrF 3 concentration and heat treatment conditions such as temperature and duration time were varied to adjust the relative intensity of blue (EL), green and red (PL). The formation of LaF 3 crystals within the glass ceramic and their effect on the visible spectra are discussed. The glass ceramics were mounted on top of a blue LED to fabricate a wLED, and demonstrate its practical feasibility, with a wide color gamut of up to 120% of the NTSC. • A color converter with Pr3+ -doped oxyfluoride glass ceramic was fabricated. • Balanced RGB emission intensities were obtained after heat treatment. • A white LED was composed and showed color gamut up to 120% of NTSC. • The effect of LaF 3 crystal formation on the visible spectra was discussed. [ABSTRACT FROM AUTHOR]

Abstract: Spectral bandwidth of spontaneous Raman scattering of tellurite glasses was significantly widened upon introduction of MoO3 or WO3. Tellurite glasses modified with MoO3 presented Raman scattering spectra with full width at half maximum of ∼300cm−1 centered at Stokes shift of ∼800cm−1 without much reduction of its relative Raman scattering coefficient. Such enhancements of the Raman scattering characteristics of the modified tellurite glasses, together with their good thermal stability, proposed their high potential as a wideband fiber Raman amplifier for optical communications. Broadening of the Raman scattering bandwidth is discussed in terms of structural changes accompanied. [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]

A phosphor-in-glass (PiG) was fabricated to realize a robust white light emitting diode (wLED) with wide color gamut. β-SiAlON:Eu2+ and CaAlSiN 3 :Eu2+ were employed for the green and red phosphors, respectively. Nd 2 O 3 doped silicate glass was used to reduce the emission bandwidths of the phosphors, utilizing the hypersensitive transition of Nd3+: 4I 9/2 → 4G 5/2 , 2G 7/2. The content of green and red phosphors was varied to produce a white emission. The emission spectra, color coordinates and color gamuts of the wLEDs with the PiGs were examined by varying phosphors and Nd 2 O 3 content. A wLED with 5 mol% Nd 2 O 3 doped glass had an enhanced color gamut up to 88%. The thermal stability of the PiGs was also monitored to demonstrate its practical feasibility as a white light source in display applications. • A white LED was realized with a PiG using β-SiAlON:Eu2+ and CASN:Eu2+. • The color gamut has been enhanced up to 88% by introducing Nd-doped silicate glass. • The PiG showed high thermal stability and its practical feasibility. [ABSTRACT FROM AUTHOR]

Abstract: The effect of CsBr/Ga ratio on the blue upconverted emission from Nd3+/Pr3+ in Ge–Ga–S–CsBr chalcohalide glasses was investigated. When CsBr/Ga was smaller than unity, the energy transfer from Nd3+ to Pr3+ ions was dominant and blue emission centered at ∼495nm (Pr3+:3P0 → 3H4) was observed. On the contrary, the intensity of the upconversion luminescence from Nd3+ increased at the expense of the blue emission when CsBr/Ga ratio exceeded unity. The possible relationship between the composition-dependent blue emission and the local environment of rare earth ions was discussed. [ABSTRACT FROM AUTHOR]

High-refractive index glasses are used to produce glass lenses by the precision optical Glass Mold Press (GMP) process and have been extensively studied because of increased demand for their application in telecommunications, optical lenses, and cameras. Borate glasses containing Ta 2 O 5 , Nb 2 O 5 , La 2 O 3 and Gd 2 O 3 have mainly been used as materials for GMP because of their excellent optical properties and low production cost. This study conducted a systematic investigation of the B 2 O 3 –La 2 O 3 –Ta 2 O 5 –SiO 2 quaternary glass system for precision GMP applications. The glass forming range of the quaternary system was studied using (B 2 O 3 +SiO 2)–La 2 O 3 –Ta 2 O 5 and changes in physical and thermal properties such as refractive index, density and glass transition temperature of the obtained glasses were examined. Compositional dependent structural changes were also inspected by Raman spectroscopy and solid state nuclear magnetic resonance (NMR) analyses, to determine the compositions' effect on thermal and optical properties. [ABSTRACT FROM AUTHOR]

High-refractive index glasses are used to produce glass lenses by the precision optical Glass Mold Press (GMP) process and have been extensively studied because of increased demand for their application in telecommunications, optical lenses, and cameras. Borate glasses containing Ta 2 O 5 , Nb 2 O 5 , La 2 O 3 and Gd 2 O 3 have mainly been used as materials for GMP because of their excellent optical properties and low production cost. This study conducted a systematic investigation of the B 2 O 3 –La 2 O 3 –Ta 2 O 5 –SiO 2 quaternary glass system for precision GMP applications. The glass forming range of the quaternary system was studied using (B 2 O 3 +SiO 2)–La 2 O 3 –Ta 2 O 5 and changes in physical and thermal properties such as refractive index, density and glass transition temperature of the obtained glasses were examined. Compositional dependent structural changes were also inspected by Raman spectroscopy and solid state nuclear magnetic resonance (NMR) analyses, to determine the compositions' effect on thermal and optical properties. [ABSTRACT FROM AUTHOR]

The formation mechanism of Cd–S–Se quantum dots (QDs) with a CdS/CdSe core–shell structure within a silicate glass system was investigated by monitoring the change in the first excitonic absorption peak of CdSe, CdS, and Cd–S–Se QDs as a function of the heat‐treatment (HT) duration. When a silicate glass containing QD formation components for CdSe or CdS single‐phased QDs was heat‐treated, CdSe QDs grew via Ostwald ripening, whereas CdS QDs hardly formed within the given silicate glass matrix. When the glass, including CdO, ZnSe, and ZnS, was utilized for the synthesis of Cd–S–Se QDs within the glass matrix, Cd–S–Se QDs were successfully formed and exhibited similar growth behavior to CdSe QDs during the initial stage of HT. The structural changes in the QD‐embedded glasses during HT were also monitored by Raman spectroscopy and discussed, and a possible formation mechanism of CdSe/CdS core–shell‐structured QDs within silicate glasses is suggested. [ABSTRACT FROM AUTHOR]

Thick‐film phosphor‐in‐glasses (PiGs) were fabricated via a screen‐printing method with various phosphor layer structures, to compose a white light emitting diode (LED). Green (Lu3Al5O12:Ce3+) and red (CaAlSiN3:Eu2+) phosphors were mixed, layered, and patterned on a glass substrate. The chromaticity of each structured PiG was tuned to achieve a white LED by varying phosphor content and thickness. The emission spectra and the related various color conversion properties, including color coordinates, correlated color temperature (CCT), color rendering index (CRI), luminous efficacy (LE) and the color gamut of the mounted PiGs with different phosphor layer structures were examined and compared. Time‐resolved photoluminescence (TRPL) measurements of the white LEDs with various phosphor layer structural designs were also obtained and compared. It was observed that spectral variation depended on the PiG layer structure. A proper PiG layer structural design was discussed for practical applications. [ABSTRACT FROM AUTHOR]

In an effort to enhance transcriptability of quasi-three-dimensional patterns present in silicon stamp onto the surface of ‘bulk’ chalcogenide glass, a buffer layer was introduced during the replication process via imprinting. Dissimilar patterns with diverse depths along the surface normal direction were imprinted with or without the buffer layer, and the resulting patterns on the glass surface were compared with regard to the transcription quality in both the lateral and vertical directions. After assessing the processing conditions appropriate for imprinting bulk As 2 S 3 glass especially in terms of temperature and duration, candidate materials suitable for the buffer layer were screened: Commercially available polydimethylsiloxane was then chosen, and impact of this buffer layer was elucidated. The imprinted patterns turned out to become more uniform over large surface areas when the buffer layer was inserted. This finding confirmed that the use of buffer layer conspicuously enhanced the transcriptability of imprinting process for bulk chalcogenide glass. [ABSTRACT FROM AUTHOR]

An oxyfluoride glass-ceramic containing Eu2+-doped nepheline and LaF 3 crystals was synthesized with varying compositions to modify its color conversion and quantum efficiency under ultra-violet light emitting diode (UV-LED) excitation. Glass composing elements such as SiO 2 , Na 2 O and Al 2 O 3 were exchanged with LaF 3 to influence the formation of nepheline crystals within the glass matrix. Among the various combinations, when Al 2 O 3 was replaced by LaF 3 there was improvement in the observed emission intensity and photo-luminescence quantum yield (PL-QY). The optimum composition of Al 2 O 3 and LaF 3 content was investigated to improve PL-QY. X-ray diffractometer (XRD) was used to monitor structural changes in the crystals within the glass-ceramic. A white LED, with a high color rendering index (CRI) comparable to commercial white LEDs, was successfully demonstrated using the modified glass-ceramic as a color converter in structures of phosphor in silicone and phosphor in glass. • Oxyfluoride glass ceramic containing Eu2+-doped nepheline was fabricated. • PL-QY was improved by the modification of glass ceramic composition. • Phosphor in glass and phosphor in silicone were composed with the glass ceramic. • White LED with high CRI up to 85 was successfully achieved. [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]

Silicate glasses with CdS and CdSe quantum dots ( QDs) were synthesized for application as an inorganic color converter for a 450-nm blue light-emitting diode ( LED). CdO and ZnS (or ZnSe) were added, and heat treatment conditions were changed to control QD formation within the silicate matrix. Absorption spectra and high-resolution transmission electron microscopy confirmed the QD formation. Variations in absorption and photoluminescence ( PL) spectra were observed with CdSe QD-embedded glasses when heat treatment conditions varied, whereas glasses with CdS QDs did not show noticeable variation. QD-embedded glasses were then mounted on top of a 450-nm LED chip to make a color-converted LED, and their electroluminescence and PL spectra as well as CIE color coordinates were investigated. The practical potential of QD-embedded glasses as an inorganic color converter has been observed, and their spectral properties were discussed. [ABSTRACT FROM AUTHOR]

We report the optical and structural studies of Eu3+-doped 1-dimensional CaYAl3O7 nano-fiber phosphor. CaYAl3O7:Eu3+ phosphors were synthesized by electrospinning technique and the pristine nano-fibers were annealed at 900°C to form well crystallized uniform fibers. Under ultraviolet excitation, the CaYAl3O7:Eu3+ exhibited red emission, due to transitions in the 4f states of Eu3+. In order to explore the difference between the quantum efficiency of nano-fiber and bulk CaYAl3O7:Eu3+ phosphor, detailed structural and optical analyses were carried out. The structural analysis of the CaYAl3O7:Eu3+ nano-fibers indicates that the structural environment surrounding the dopant Eu3+ ion was more unstable in nano-fiber when compared to a bulk sample. Decay curves for both the samples when fitted with double exponential decay model indicate that the nano-fiber has shorter decay time, arising from the larger contribution from the non-radiative decay, due to defect levels introduced in the host lattice. [ABSTRACT FROM AUTHOR]

Abstract: A full-color-emitting phosphor, CaYAl3O7:Pr3+,Ce3+ was synthesized through conventional solid-state reaction. The structural properties of the phosphor were analyzed by Rietveld refinement, maximum entropy method, and luminescent properties were analyzed by co-activating with different rare earth ions. Photoluminescence spectra on excitation with 450nm source were dominated by green band at 490nm originating from 3P0→3H4 transition of Pr3+ ions and less intense band at 617nm due to 1D2→3H4 transition. On codoping with Ce3+, phosphor exhibits an additional broad band originating from 5d1→4f1 (2F7/2 and 2F5/2) of Ce3+, centered at around 540nm due to efficient energy transfer from Pr3+ levels to Ce3+ levels. With this emission property we recommend CaYAl3O7:Pr3+,Ce3+ as potential single-phase full-color-emitting phosphor for solid-state lighting applications. [Copyright &y& Elsevier]

Thulium (Tm3+)-doped boro-tellurite glasses were prepared by melt-quenching technique and their optical, photo-luminescence (PL), and time-resolved spectroscopic behaviors were studied. The Judd-Ofelt (J-O) parameters were calculated from the absorption spectra and evaluated the radiative factors for emission transitions. The PL and up-conversion (UC) emission spectra were measured under the excitation wavelengths of 473, and 793 nm diode lasers, respectively. The emission peak of 3H 4 →3H 6 (793 nm) and up-conversion 3F 2,3 → 3H 6 (696 nm) transitions shifted to higher wavelengths with the increment of Tm 2 O 3 concentration, while the 1G 4 →3F 4 (650 nm), 3H 4 →3F 4 (1466 nm) and 3F 4 →3H 6 (1821 nm) transitions showed no change in peak positions, under 473 nm laser excitation. The time-resolved spectroscopic measurements are recorded and analysed for all transitions. Under 793 nm laser, NIR emission spectra (1200–2200 nm) and spectroscopic characteristics were measured to discuss the energy transfer mechanisms. The strong transitions of 3H 4 →3F 6 (1466 nm) and 3F 4 →3H 6 (1821 nm) were observed and corresponding emission cross-section and gain factors have been evaluated and discussed for the application of the S-band communication window. • Tm3+ concentration-dependent borotellurite glasses were synthesized. • Structural and optical characteristics were studied and discussed. • Judd-Ofelt intensity parameters were evaluated and compared. • Photoluminescence and upconversion emission features were investigated. • The present glass showed high NIR emission cross-section at 1.8 μm. [ABSTRACT FROM AUTHOR]

Silicate based alumino-sodium (SAS) glasses were fabricated with various alkali (Li 2 O and K 2 O) and alkaline-earth metal (MgO and CaO) oxides to study their influence on chemical strengthening characteristics such as surface compression stress (CS) and depth of layer (DOL) after ion exchange of Na+ with K +. Introducing Li 2 O instead of Na 2 O decreased DOL while increasing CS up to 5.0 mol. % of Li 2 O. In contrast, replacing Na 2 O content with K 2 O increased DOL while decreasing CS. When alkaline-earth oxides such as MgO and CaO were substituted for Na 2 O, both CS and DOL decreased. Micro-Raman spectroscopy was used to study structural changes induced by alkali and alkaline-earth oxides and their impact on ion exchange properties. The inter-diffusion coefficients of K + ions were predicted by employing the Boltzmann-Matano equation to support the chemical strengthening effect of various alkali and alkaline-earth elements in SAS glasses. [ABSTRACT FROM AUTHOR]

A method is reported that uses visible continuous-wave laser to directly fabricate micropatterns in glasses containing silver ( Ag) nanoparticles. Ag nanoparticles were formed in the glass using thermal treatment. Upon laser irradiation, Ag nanoparticles with their surface plasmon in resonance with the laser beam were partially melted and decreased in size due to the temperature increase induced by the excited Ag nanoparticles. Three-dimensional patterns were achieved by scanning the laser beam through the thickness of the glass. [ABSTRACT FROM AUTHOR]

Abstract: Absorption and emission spectra for the 3H4↔(3F2, 3H6) transition of Pr3+ ions embedded in Ge–Sb–Se glasses turned out to change systematically upon the introduction of a small amout of Ga. Clear blueshift of the absorption peak wavelengths together with the decrease of absorption cross-section was evident in these glasses containing Ga. We believe that the Ga addition into the conventional covalent selenide glasses makes chemical bonds between rare earth atoms and Se atoms more ionic due to preferential location of the GaSe4 tetrahedra at the second coordination shell of a rare earth atom. Taking into consideration the hypersensitive nature of the Pr3+: 3H4↔3F2 transition, the observed blueshift may manifest the enhanced ionicity of the chemical bonds between Pr and Se in the current Ga-containing glasses. [Copyright &y& Elsevier]

Abstract: LaPO4:Er3+and LaPO4:Er3+/LaPO4 core/shell nanoparticles were synthesized in a high-boiling mixture solution of tributyl phosphate, trihexylamine and diphenylether. LaPO4:Er3+ nanoparticles of a spherical shape with a mean diameter of 5.0nm were formed, while LaPO4:Er3+/LaPO4 core/shell nanoparticles resulted in an increase of the average size of nanoparticles (9.0nm). The homogeneous inorganic–organic nanohybrid materials including LaPO4:Er3+ and LaPO4:Er3+/LaPO4 core/shell nanoparticles were prepared by dispersing the nanoparticles into the silica-based resin, which was synthesized by non-hydrolytic sol–gel method from (3-glycidyloxypropyl) trimethoxysilane (GPS), diphenylsilanediol (DPSD) and phenyltrimethoxysilane (PTS). The highly visible transparent films of crack-free thick thickness were fabricated by a single step spin-coating from the nanohybrid materials. The films containing LaPO4:Er3+/LaPO4 core/shell particles showed the enhanced emission intensity and lifetime compared to those with LaPO4:Er3+. [Copyright &y& Elsevier]

Abstract: It has been experimentally demonstrated that the indium tin oxide can be doped with rare earth element through the conventional sol–gel technique. Erbium in its trivalent state replaces the indium site in the indium tin oxide lattice. Homogeneously distributed and optically activated Er3+ ions then allow a strong photoluminescence emission at ∼1.5μm. Reduced particle size and the existence of Sn are believed to affect the local structural environments of doped Er3+ ions, thus contributing to the radiative emission properties: Large spectral bandwidth without concentration quenching is useful for practical applications. [Copyright &y& Elsevier]

Lifetime of excited electronic states inside the 4f configuration of rare-earth elements embedded in covalent chalcogenide glasses turns out to be sensitive to medium-range structural phase transition of the host glasses. We have measured lifetimes of 1.6 μm emission originating from Pr3+: (3F3, 3F4)→3H4 transition in amorphous Ge–Sb–Se alloys. The longest lifetime is measured at around the mean coordination number of ∼2.67, which arises coincidently from structural changes of the host glasses from two-dimensional layers to three-dimensional networks. [Copyright &y& Elsevier]

Cd‐S‐Se quantum dot embedded glasses (QDEGs) with dual‐band emissions of green and red were synthesized by assembling two QDEGs, to obtain a color converter for white LEDs (wLEDs) with a wide color gamut and long‐term stability. Each QDEG, possessing different sizes of QD, was prepared by adjusting heat‐treatment conditions. They were then bonded to each other by an additional heat treatment to fabricate a pattern structured QDEG (pQDEG). The fabrication conditions of the pQDEGs, such as their heat‐treatment condition and thickness, were varied to improve the color gamut. pQDEG‐based WLEDs were demonstrated and their optical properties such as color coordinates, luminous efficiency, and color rendering index (CRI) were monitored. The effect of pQDEG fabrication conditions on the resultant emission spectra and color gamut were discussed. [ABSTRACT FROM AUTHOR]

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]

Silicate glasses based on SiO 2 –B 2 O 3 -BaO-WO 3 (SBBW) are synthesized with varying added Al 2 O 3 content, and their thermal and structural properties are examined as a sealing material for reversible solid oxide fuel cells (RSOCs). When up to 17.5 mol%, Al 2 O 3 is added, glass stability is improved at the expense of viscosity at sealing temperature. The glass transition temperature (T g), coefficient of thermal expansion (CTE) and flow at sealing temperature are investigated while varying Al 2 O 3 content, to find the proper composition for RSOC sealing. The structural changes in the glasses resulting from the Al 2 O 3 are inspected using Raman spectroscopy and an X-ray diffractometer. The adhesion characteristics of the glasses are examined by applying the glasses between NiO-yittria stabilized zirconia (NiO-YSZ) and Crofer22APU. A RSOC stack with 15 cells is prepared with glass containing 10 mol% of Al 2 O 3 as a sealing material, and the practical feasibility of the glass is successfully demonstrated. The open circuit voltage is monitored while cycling the RSOC stack between water electrolysis mode and fuel cell mode. [ABSTRACT FROM AUTHOR]

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]

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]

Nd3+-doped silicate glass (Nd-glass) was employed as a color filter for a white LED based on red and green phosphor (RG-LED), to manipulate the photoluminescence spectral shape and thus to provide a wider color gamut. The hypersensitive transition of Nd3+:4I9/2→4G5/2,2G7/2 was adjusted via glass composition and Nd concentration, and improved absorbance as well as reduced the absorption bandwidth. The effective absorption of the Nd-glass at ~580 nm reduced the spectral linewidth of the green and red emissions, improving the color reproduction range. The color gamut of the RG-LED was improved from 75.3% to 81.6% NTSC by the introduction of Nd-glass as a color filter. Reliability under high operating current and high temperature were also examined and discussed. [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]

Phosphor-in-glass (PiG) thick film was fabricated on a borosilicate glass substrate using a conventional screen printing method and employing phosphosilicate glass to allow low-temperature sintering. The vehicle content and sintering temperature were optimized to form a thick film with a thickness of ~50 μm. Commercial yellow (Y3Al5O12:Ce3+) and red (CaAlSiN3:Eu2+) phosphors were successfully incorporated within the glass matrix and then sintered at 550°C. Color-tunable white LEDs were achieved using the PiG thick films as a color converter by varying the glass to phosphor (GtP) ratio. The high luminous efficacy of up to ~120 lm/W and high color rendering index of up to 89 in combination with the thermal quenching property prove the practical feasibility of the PiG thick films for high-power/high-brightness LED applications. [ABSTRACT FROM AUTHOR]

Phosphor in glasses (PiGs) were fabricated for color tunable white LEDs using glass of the SiO 2 -B 2 O 3 -ZnO-Na 2 O system, which can be sintered at 550 °C. CaAlSiN 3 :Eu 2 + (CASN:Eu 2 + ) red phosphor was added without its thermal degradation, and a mixture with Y 3 Al 5 O 12 :Ce 3 + (YAG:Ce 3 + ) yellow phosphor demonstrated color tunable white LEDs when mounted on a blue LED. Variation of the glass to phosphor and phosphor to phosphor mixing ratio achieved a highly improved color rendering index (CRI), of up to 93. Thermal quenching property was also improved, reaching 98% of its original intensity even at 200 °C; the value depended on the phosphor content. Thermal conductivity values elucidate the improvement. [ABSTRACT FROM AUTHOR]

BaF 2 –Al 2 O 3 –B 2 O 3 –SiO 2 glasses and glass-ceramics doped with Eu3+-Tb3+ were fabricated as an inorganic color converter for white LEDs. The BaF 2 –Al 2 O 3 –B 2 O 3 glass composition was modified by adding SiO 2 , and thermal and mechanical stability improved with increasing SiO 2 content while maintaining a quantum yield (QY) as high as 91%. To realize white color coordinates, Tm3+ was additionally introduced at varying contents, and Eu3+ content was also controlled. Excellent chromatic properties, such as a pure white color coordinates (x = 0.33, y = 0.33) with a co-related color temperature of 5772K, and a color rendering index (CRI) of 91 under 370 nm excitation, were successfully achieved. After the glass was heat-treated at 600 °C to fabricate a glass ceramic, the glass-ceramics were mounted on top of a 370 nm UV-LED, successfully demonstrating a white LED with nearly pure white color coordinates and a high CRI of 86. The increased emission intensity in the glass-ceramic was attributed to the formation of BaF 2 crystals which were investigated by X-ray diffractometer (XRD) and a transmission electron microscope with energy dispersive spectroscopy (TEM-EDS). • Glass composition was modified to improve mechanical and thermal properties. • Tm3+ ions were additionally doped for blue emission under UV light. • Tb-Eu-Tm contents were adjusted to make a white color coordinate. • Emission intensity was improved with heat treatment at 600 °C for 10hrs due to form the BaF 2 crystal. • White color coordinate (0.36, 0.36) was successfully achieved with high CRI of 85 under 370 nm UV LED chip. [ABSTRACT FROM AUTHOR]

SiO 2 –Na 2 O–Al 2 O 3 –LaF 3 glasses were doped with various rare earth ions to find the proper active ions for blue LED (λ = 455 nm) color conversion. Based on photo-luminescence (PL) spectra, a combination of Dy 3+ and Ho 3+ was selected and their visible spectroscopic properties were investigated for possible candidate of white color conversion of a blue LED. Concentrations of Dy 3+ and Ho 3+ were varied to find the proper combination, and 2 mol% DyF 3 and 1 mol% HoF 3 co-doped glass showed reasonable visible emissions. When the glasses were heat treated, emission intensities from both ions were clearly increased by the formation of LaF 3 nano-crystals, which were identified by X-ray diffraction and TEM analyses. Emission peak at ~ 525 nm newly appeared due to nano-crystal formation and the related local phonon energy change nearby Dy 3 + ion. Energy transfer between Dy 3 + and Ho 3 + was also observed and discussed. Photo-luminescence excitation (PLE) spectra were measured and also discussed. [ABSTRACT FROM AUTHOR]

Sulfur-based chalcogenide Li–Ge–Ga–S powders for use in solid electrolyte of Li + ion batteries have been successfully synthesized via a low-temperature solution-based process. Their Li + ion conductivity turns out to be ~ 7 × 10 − 4 S/cm at room temperature which is quite comparable with that of melt-quenched or mechanically-alloyed analogues. It is revealed that their microstructure becomes amorphized appropriately at a specific Ga/Ge ratio where the ionic conductivity is maximized. A structural model is proposed, which emphasizes correlations between gallium and lithium inside the amorphous structures. [ABSTRACT FROM AUTHOR]

SiO 2 –Na 2 O–Al 2 O 3 –LaF 3 glasses doped with Eu 2+ and Eu 3+ were synthesized to realize an inorganic color converter for white LED using 400 nm UV LED. Among various rare earth ions, Eu 2+ and Eu 3+ showed prominent emission under 400 nm LED excitation. Carbon and EuF 3 content were varied to control the ratio of Eu 2+ and Eu 3+ during the melting process. When the ratio of Eu 2+ and Eu 3+ within the glass matrix was properly controlled, color coordinates of the photoluminescence spectra could be adjusted to make white colors under 400 nm LED excitation. The emission intensity was increased with subsequent heat treatment which led to the formation of LaF 3 nano-crystals. However, almost no conversion was observed when the glasses were actually mounted on UV-LED to make a white LED. Heavy crystallization of the oxyfluoride glasses was thus investigated to improve its scattering of the light source and color conversion efficiency, and its practical feasibility as an inorganic UV-LED color converter was demonstrated. [ABSTRACT FROM AUTHOR]