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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]

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]

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]

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]

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]

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]