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By combining the spectroscopic quality of a crystalline phase with the outstanding thermal and chemical stability of the matrix glass, nanocrystal‐in‐glass composites (NGCs) exhibit excellent optical properties. However, strong interfacial diffusion occurs during high‐temperature encapsulation, leading to the erosion of the nanocrystals and detrimental effects on the final performance. The control of interfacial diffusion has so far relied on intuition and experience, with the underlying physical mechanisms remaining largely unknown. In this study, through atomistic simulations and experimental verification, we have developed atomic models of NGCs, revealing the dynamic characteristics of the interface and elucidating how the glass structure can regulate the interface diffusion. Finally, we demonstrate how a tunable interface can be achieved through compositional adjustments of the glass matrix. [ABSTRACT FROM AUTHOR]

Glass ceramics may exhibit enhanced functionalities compared to the glass and crystal counterparts due to the synergistic effect with the "1+1 > 2" feature in a cooperative manner. Nonlinear optical property is expected to be next breakthrough in presenting synergistic effect in glass ceramics. In this article, we give a comprehensive review of the recent progress of the development in nonlinear glass ceramics with unique photonic domain structure, emphasizing their synergistic effect in nonlinear response. The applications in photonics of the nonlinear glass ceramics are also described. Finally, we also present the opportunities and challenges for further exploring synergistic effect in nonlinear response in glass ceramics. [ABSTRACT FROM AUTHOR]

Broadband near‐infrared (NIR) photonic materials have wide applications. Although extensive studies on rare‐earth, transition‐metal, and even semiconductor‐activated materials have enabled the development of a rich NIR material pool, developing broadband and efficient photonic candidates covering the NIR I and II regions from 750 to 1500 nm has been met with limited success. Here, it is reported that a subnano Te cluster with a characteristic configuration different from that of the ion state may fill the aforementioned gap. Further, a strategy is proposed for the in situ generation and stabilization of Te clusters by tuning the cluster evolution in glass. A novel active photonic glass embedded with a Te cluster is fabricated; it exhibits intense and broadband short‐wave NIR luminescence with a central wavelength at 1030 nm and a bandwidth exceeding 330 nm. Interestingly, the glass exhibited a full visible‐spectrum conversion ability from 300 to 800 nm. The application of this unique broadband excitation feature for night vision and tissue penetration is demonstrated using a smartphone as the excitation source. These findings demonstrate a fundamental principle of cluster design in glass for creating new properties and provide a new direction for developing novel cluster‐derived functional composite materials. [ABSTRACT FROM AUTHOR]

High‐brightness phosphor‐converted solid‐state light (SSL) sources based on blue light‐emitting diodes (LEDs) or laser diodes (LDs) will enable versatile optical applications other than general illumination. However, luminescence ceramics/crystals are too expensive for widespread use, while phosphor‐in‐glass converters suffer from low conversion efficiency at high‐power‐density excitation and poor chemical and thermal stabilities of low‐melting glasses. Herein, an ultrathin interface (<50 nm) is reported in Lu3Al5O12:Ce3+ phosphor‐in‐silica‐glass (LuAG:Ce‐PiSG) despite being sintered at 1250 °C, endowing them with high internal quantum efficiency (>95%) and excellent stabilities. Combined experimental results and first‐principles calculations reveal that the large formation energy of SiAl point defects makes the undesired interfacial reaction between aluminate garnets and silica glass intrinsically suppressed. Phosphor‐converted LEDs/LDs fabricated by LuAG:Ce‐PiSG exhibit high luminous efficiency (195 lm W−1 @ 20 mA) and high brightness (1914 lm @ 13.4 W mm−2), approaching the performances of their ceramic counterparts. The results not only provide a way to balance the brightness and the price for SSL sources but also unleash the potential of silica glass as an inorganic matrix for emerging optical applications. [ABSTRACT FROM AUTHOR]

The information burst in modern society poses new challenges to information preservation technology, both in storage efficiency, capacity, and security. Multi‐dimensional optical data storage based on the femtosecond laser direct writing technique is a promising way to face these challenges. Herein, a new optical storage method based on femtosecond laser‐induced local darkening of CdSe quantum dots doped glass is reported. Photoluminescence image and spectrum indicate that highly luminescent well‐crystallized CdSe quantum dots can be amorphized by a single femtosecond laser pulse and reconstructed by thermal treatment, resulting in reversible luminescence modulation, in which the luminous efficacy of CdSe quantum dots in glass matrix was well recovered after each cycle of writing and erasing. Complicated patterns written inside the glass and multi‐layer information are also successfully inscribed and well demonstrated. Data bit could be written by just one 380 fs single pulse with pulse energy as low as 100 nJ. The present work provides a potential way for three‐dimensional optical information storage and data encryption with low power consumption, fast writing speed, large capacity, and high security. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) are newly emergent broadband light sources for miniaturizing optical systems like spectrometers. However, traditional converters with NIR phosphors encapsulated by organic resins suffer from low external quantum efficiency (EQE), strong thermal quenching as well as low thermal conductivity, thus limiting the device efficiency and output power. Through pressureless crystallization from the designed aluminosilicate glasses, here broadband Near‐infrared (NIR) emitting translucent ceramics are developed with high EQE (59.5%) and excellent thermal stability (<10% intensity loss and negligible variation of emission profile at 150 °C) to serve as all‐inorganic visible‐to‐NIR converters. A high‐performance NIR phosphor‐converted light emitting diodes is further demonstrated with a record NIR photoelectric efficiency (output power) of 21.2% (62.6 mW) at 100 mA and a luminescence saturation threshold up to 184 W cm−2. The results can substantially expand the applications of pc‐LEDs, and may open up new opportunity to design efficient broadband emitting materials. [ABSTRACT FROM AUTHOR]

The diverse optoelectronics systems can provide interesting design inspiration for photonics devices, ranging from optical modulators to light‐emitting displays. With the increasing applications and requirements of optical interconnect in complex environments, an essential operation is increasingly being pursued to exploit the consolidation of various merits of basic components. Here, an optical gain from monodisperse CsPbBr3 quantum dots crystallized in a selected transparent glass is revealed. The threshold of amplified spontaneous emission increases from 7.4 to 100.4 µJ cm−2 with the temperature from 78 K to room temperature, accompanied with a high gain coefficient of 627.9 cm−1. A small fluctuation of the lifetime (≈10.5%) with temperature and the photostability (>12 h) with the excitation of femtosecond laser indicates the robustness of the crystallized CsPbBr3 quantum dots in the transparent glass. These demonstrations present a deep understanding of the optical gain in the composite of metal halide perovskites and transparent glass and pave a path for the potential applications of CsPbBr3‐based glass–ceramics as a gain medium for coherent light sources including laser/incoherent diode, fiber laser as well as optical amplifier chips. [ABSTRACT FROM AUTHOR]

Laser‐driven (LD) lighting is emerging as the next‐generation high‐power solid‐state lighting technology. All‐inorganic color converters with high quantum efficiency (QE), small thermal quenching, high thermal conductivity, and high thermal and chemical stabilities are crucial to coping with the enormous heat generated in LD lighting. Although luminescent translucent ceramics are the most promising class of color converters, only green/yellow‐emitting ones with satisfactory performance are developed before. Here, a far‐red‐emitting composite ceramics Y3Al5O12 (YAG)–Al2O3:Cr3+ with near‐unity internal QE and zero‐thermal quenching are prepared via pressureless glass crystallization, where the inside light scattering is finely tuned by simply manipulating the temperature to induce controllable grain growth. The commonly used inert matrix Al2O3 here becomes an optically active component as YAG, thus alleviating the undesired concentration quenching while maintaining strong light absorption. Therefore, a high‐power LD far‐red lighting source with luminescence saturation threshold up to 21.4 W mm−2 is demonstrated, which may find broad applications in plant growth lighting, solar simulators, and phototherapy. [ABSTRACT FROM AUTHOR]

Tetra‐valent manganese (Mn4+) has been regarded as an efficient non‐rare‐earth red‐light emitting ion, which has stimulated continued search of robust hosts and efficient synthetic methods to stabilize Mn4+ centers with strong photoluminescence. In this work, we demonstrate a facile synthetic method for Mn4+ doped glass‐ceramic (GC) based on crystallization‐induced oxidation state change in an oxide glass. The parent glass with a formula of LiNaGe4O9 is fabricated by melt‐quenching and crystallization is induced by thermal treatment in air. Oxidation of Mn2+ in glass to Mn4+ in the GC is confirmed by both optical spectroscopy and electron paramagnetic resonance (EPR) measurements. After thermal treatment, the characteristic reddish photoluminescence (PL) of Mn2+ in the glass centered at 611 nm disappears and a strong photoluminescence peak at 660 nm attributed to Mn4+ is observed. The conversion to Mn4+ after crystallization in the examined system may have strong implications for synthesis of Mn4+ doped phosphors which always requires rigorous control of the redox equilibrium during synthesis. [ABSTRACT FROM AUTHOR]

Broadband and tunable near-infrared (NIR) emission of Ni2+ doped glass–ceramics (GCs) is highly attractive due to their potential to address the challenge of broadband optical amplification in the optical communication band. However, optical activity of Ni2+ in different glass matrix as well as nucleation and crystallization processes in relevant glasses have not been understood fully. Here, broadband NIR photoluminescence was realized through precipitation of LiGa5O8:Ni2+ nanocrystals (NCs) within an alkali gallium-silicate glass matrix by melt-quenching and successive heat treatment. Upon exciting by a 980 nm laser diode, we observed NIR photoluminescence band centered at ~ 1310 nm with full width at half maximum of wider than 300 nm, which was originated from 3T2g(3F) → 3A2g(3F) electronic transition of octahedral coordinated Ni2+ in LiGa5O8 NCs embedded in the GCs. Controlled precipitation of NCs, LiGa5O8:Ni2+ and Ga2O3:Ni2+ were achieved by tailoring the composition of alkali gallium-silicate glass matrix. ab initio molecular dynamics simulation was carried out to clarify the formation of nanophases in the glass system. We confirmed that optical properties of transparent GCs containing Ni2+ NCs can be realized by changing molar percentages of Ga2O3. Our results offer a new insight into the precipitation of NCs in oxide glasses and Ni2+ doped GCs, which may be applicable in the photonic fields, such as optical amplifier and laser. [ABSTRACT FROM AUTHOR]

Monolithic luminescent glass‐ceramic is highly desirable for solid‐state lighting as it is stable and robust, while in practical light‐emitting devices only a thin luminescent layer is used for more efficient excitation and light extraction. In this paper, Mn2+‐doped glass and glass‐ceramic with the composition of 60SiO2‐8Na2O–20ZnO–12Ga2O3 were fabricated by the conventional melt‐quenching technique. We observe that the crystallization of α‐Zn2SiO4 nanocrystals takes place on the glass surface with controllable thickness after heat treatment. The glass samples show typical red emission peaking at λ = 620 nm that can be ascribed to the spin‐forbidden 4T1g(G) → 6A1g(S) transition of Mn2+ (d5) located in the octahedral coordination site of the glass host. After surface crystallization this red emission is retained and a new green emission at 528 nm is observed through the control of the crystallization temperature and duration, thus offering tunable emission characteristics promising for the lighting application. This change in the visible emission is interpreted in terms of the change of coordination state of Mn2+ from octahedral in a glass matrix to tetrahedral in the surface precipitated α‐Zn2SiO4 crystals. [ABSTRACT FROM AUTHOR]

Abstract: It is well recognized that a widely wavelength‐tunable mid‐infrared (MIR) fiber laser plays an important role in the development of compact and efficient coherent sources in the MIR range. Herein, the optimizing Er/Ho ratio for enhancement of broadband tunable MIR emission covering 2.6‐2.95 μm in the Er3+/Ho3+‐codoped transparent borosilicate glass‐ceramic (GC) fibers containing NaYF4 nanocrystals under 980 nm excitation was investigated. Specifically, the obtained GC fibers with controllable crystallization and well fsd‐maintained structures were prepared by the novel melt‐in‐tube approach. Owing to the effective energy transfer between Er3+ and Ho3+ after crystallization, the 2.7 μm MIR emission was obviously enhanced and the emission region showed a notable extension from 2.6‐2.82 μm to 2.6‐2.95 μm after the addition of Ho3+. Importantly, we conducted a theoretical simulation and calculation related to the MIR laser performance, signifying that the GC fiber may be a promising candidate for MIR fiber laser. Furthermore, the melt‐in‐tube approach will provide a versatile strategy for the preparation of diverse optical functional GC fibers. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we report upconversion (UC) luminescence enhancement in LaBGeO5:Yb3+, Er3+ glass‐ceramics (GCs), surface crystallized glass‐ceramics (SCGCs) and ceramics compared with the as‐melt glass fabricated by the conventional melt‐quenching technique. Based on structural investigations, we find that the nucleation and crystallization of trigonal stillwellite LaBGeO5:Yb3+, Er3+ nanocrystals occur first at the glass surface before the following volume crystallization. The local site symmetry around rare earth (RE) ions which was evaluated using the Eu3+ ions as a probe together with Judd‐Ofelt theory calculations exhibits a clear increase with the devitrification of the glass. Consequently, complete crystallization of the glass leads to largest enhancement in the UC emissions of the LaBGeO5:Yb3+, Er3+ ceramics. We ascribe the enhancement of UC luminescence in the LaBGeO5:Yb3+, Er3+ GCs, SCGCs, and ceramics to the structural ordering and the improvement of site symmetry surrounding RE ions that minimizes the rate of nonradiative relaxation process. [ABSTRACT FROM AUTHOR]

Cooperative upconversion luminescence (CUCL) occurs in spectral regions in which single ions do not have energy levels. However, all results reported so far are concentrated on luminescence properties from Yb3+ ions-doped various hosts. Here, we report the observation of nonlinear negative transmittance (NNT) at continuous-wavelength (CW) 980-nm laser diodes (LDs) pumping in silicate oxyfluoride glass ceramics (GCs)-containing CaF2:Yb3+ nanocrystals. The unique optical nonlinearity is analyzed based on energy-level transitions, dynamic evolution, rate equation, and power transmission equation, which can be explained as the cooperative optical absorption for the intense CUCL of Yb3+ ions. The NNT in the CaF2:Yb3+ nanocrystals-embedded GCs can be tailored with the power of a CW 980-nm LDs, which possesses potential for the development of future optical limiters and switches. [ABSTRACT FROM AUTHOR]

Glass-ceramic fibers containing Cr3+-doped ZnAl2O4 nanocrystals were fabricated by the melt-in-tube method and successive heat treatment. The obtained fibers were characterized by electro-probe micro-analyzer, X-ray diffraction, Raman spectrum and high-resolution transmission electron microscopy. In our process, fibers were precursor at the drawing temperature where the fiber core glass was melted while the clad was softened. No obvious element interdiffusion between the core and the clad section or crystallization was observed in precursor fiber. After heat treatment, ZnAl2O4 nanocrystals with diameters ranging from 1.0 to 6.3 nm were precipitated in the fiber core. In comparison to precursor fiber, the glass-ceramic fiber exhibits broadband emission from Cr3+ when excited at 532 nm, making Cr3+-doped glass-ceramic fiber a promising material for broadband tunable fiber laser. Furthermore, the melt-in-tube method demonstrated here may open a new gate toward the fabrication of novel glass-ceramic fibers. [ABSTRACT FROM AUTHOR]

Four Cr4+-activated transparent glass-ceramics containing different species of silicate nano-crystals ( Zn2 SiO4, Mg2 SiO4, Li2 ZnSiO4, and Li2 MgSiO4) were successfully prepared. Absorption spectra, photoluminescence spectra, lifetime decay curves, and quantum yield of these transparent glass-ceramics were measured. According to the crystal field strength of Cr4+-incorporated tetrahedral sites, the broadband near-infrared (NIR) luminescence of Cr4+ can be tailored from 1130 to 1350 nm and the lifetime of Cr4+ luminescence can be prolonged from 6 to 100 μs. Quantum yield in the transparent glass-ceramics containing Li2 ZnSiO4 nano-crystals reached at 17%, which is the highest value of NIR luminescence in transition-metal-activated glass materials. [ABSTRACT FROM AUTHOR]

Abstract: Transparent strontium titanium silicate glass–ceramics (GCs) containing Ni2+-doped SrTiO3 nanocrystals were synthesized by heat treatment method. Absorption spectra confirmed that the coordination environment of Ni2+ ions was changed from the trigonal bipyramid fivefold sites in as-cast glasses to the octahedral sites in the GCs. Upon 980nm laser excitation, the GCs exhibited broadband near-infrared emissions covering 1.1–1.7μm wavelength region with the full width at half maximum (FWHM) of more than 290nm and fluorescent lifetime of up to 735μs, which originated from the 3T2g (3F)→ 3A2g (3F) transition of octahedral Ni2+ ions in the SrTiO3 nanocrystals. This kind of Ni2+-doped transparent GCs have potential applications in super-broadband optical amplifiers and tunable lasers. [Copyright &y& Elsevier]

In the last decade, revolutions in photonic material design and large-area nanostructure fabrication have given researchers and technologists tools to enable a new era of ultrahigh-efficiency photovoltaics. Quantum cutting has received much attention as a potential approach to enhance the photovoltaic conversion efficiency of solar cell in the recent decades. In this article, we review the phenomena, mechanisms, and design of the quantum cutting processes, focusing on the promising applications of the transparent glasses and glass ceramic materials as the down-converter of solar spectrum. We discuss the gaps between the current theoretical analysis and the practical applications of the quantum-cutting materials. To concave the negative effects of using the quantum-cutting materials as a down-converter on the front surface of the solar cell, much attention should be given to the choice of material and improvement of the material properties as well as the integration of photonic nanostructures and circuits on the solar cell. [ABSTRACT FROM AUTHOR]

We report on the preparation of Ga/Al nanoalloys embedded glass-ceramic by heat treatment as well as femtosecond laser irradiation. The Ga/Al nanoalloys embedded glass-ceramic exhibits intense extinction in the visible region, as well as superior optical nonlinearities. The third-order nonlinear optical properties of the glass-ceramics were investigated by employing Z-scan technique. The maximum nonlinear extinction coefficient β and nonlinear refraction γ value reached 1.14 × 10−11 m/W and 2.01 × 10−17 m2/W, respectively. Three-dimensional Ga/Al nanoalloys embedded structures were also achieved in glass by scanning the focused femtosecond laser beam. These results may find applications for the fabrication of ultrafast optical switches and diffractive optical elements. [ABSTRACT FROM AUTHOR]

Furthermore, a high-power laser-driven far-red lighting source with high luminescence saturation is demonstrated. Far-Red-Emitting Ceramics: Near-Unity and Zero-Thermal-Quenching Far-Red-Emitting Composite Ceramics via Pressureless Glass Crystallization (Laser Photonics Rev. 15(7)/2021) In article number 2100060, Wenge Xiao, Guojun Zheng, Jianrong Qiu, and co-workers prepared far-red-emitting composite ceramics with near-unity internal quantum efficiency and zero-thermal quenching via pressureless glass crystallization, where the inside light scattering is finely tuned by controlling grain growth and the undesired concentration quenching is alleviated to achieve strong light absorption. [Extracted from the article]

Optical fibers have been formed by replacing precursor glass core with precursor ceramic core, in which drawing process, the precursor ceramic melted to fill the space of the core region while the clad glass was softened. Nd3+ doped LaNbO 4 nanocrystals were precipitated in the core after heat treatment. X-ray diffraction, Raman spectra, high-resolution transmission electron microscopy, electron paramagnetic resonance, optical microscope, and photoluminescence were used to characterize the obtained fiber. No crystallization, cracking, bubble, or undissolved substance is observed in the core region of precursor fiber. Nd3+ doped LaNbO 4 nanocrystals are precipitated in the core region after thermal treatment. Under the pumping source of 808 nm, three emission bands located at ∼887 nm, ∼1064 nm, and ∼1337 nm are observed, which makes this GC fiber a promising material for the NIR fiber amplifier. [ABSTRACT FROM AUTHOR]

We report on the conversion of near-ultraviolet radiation of 250–350 nm into near-infrared emission of 970–1100 nm in Yb3+-doped transparent glass ceramics containing Ba2TiSi2O8 nanocrystals due to the energy transfer from the silicon–oxygen-related defects to Yb3+ ions. Efficient Yb3+ emission (2F5/2→2F7/2) was detected under the excitation of defects absorption at 314 nm. The occurrence of energy transfer is proven by both steady state and time-resolved emission spectra, respectively, at 15 K. The Yb2O3 concentration dependent energy transfer efficiency has also been evaluated, and the maximum value is 65% for 8 mol % Yb2O3 doped glass ceramic. These materials are promising for the enhancement of photovoltaic conversion efficiency of silicon solar cells via spectra modification. [ABSTRACT FROM AUTHOR]

Transparent nanoceramics embedded with highly dense crystalline domains are promising for applications in missile guidance, infrared night vision, and laser and nuclear radiation detection. Unfortunately, current nanoceramics are strictly constrained by the stringent construction procedures such as super‐high pressure and containerless processing. Here, a pressureless crystallization engineering strategy in glass for elaboration of transparent nanoceramics and fibers is proposed and experimentally demonstrated. By intentional creation of a sharp contrast between nucleation and growth rates, the crystal growth rate during glass crystallization can be significantly suppressed. Importantly, this unique phase‐transition habit enables the achievement of transparent nanoceramics and even smooth fibers with extremely tiny crystalline size (≈20 nm) and high crystallinity (≈97%) under atmospheric pressure. This allows the generation of an attractive nonlinear optical response such as dynamic optical filtering and luminescence in the mid‐infrared waveband of 4300–4950 nm. These findings highlight that the strategy to switch the phase‐transition habit of glass into the unconventional crystallization regime may provide new opportunities for the creation of next‐generation nanoceramics and fibers. [ABSTRACT FROM AUTHOR]

Boron-mullites are potential candidate crystal phases for broadband near-infrared (NIR) luminescence in the mullite series due to their higher complexity in crystal structure and abundant [AlO 6 ] units for accommodating transition metal ions as luminescence activators. In this work, the effect of ZrO 2 and TiO 2 on the microstructure and NIR luminescent properties of mullite type Cr3+:Al 4 B 2 O 9 glass ceramics were analyzed in detail. Through characterizations including XRD, SEM, TEM and NMR, the oriented growth of strip-shaped grains in ZrO 2 doped glass ceramic samples has been verified. The proportion of [AlO 6 ] units is strongly correlated with NIR spectra, suggesting that the strategy for modulation the NIR luminescence through oriented growth can be generalized as a universal method for manipulation of the optical properties for transition metal ion activated crystals with the mullite type structure. [ABSTRACT FROM AUTHOR]

Multi-component silicate glass is an ideal matrix for fabricating glass-ceramics because of its excellent physical-chemical stability and high optical transmittance. In this paper, a series of Cr3+ doped multi-component silicate glasses were designed for the preparation of glass-ceramics that crystalizes mullite-type Cr3+:Al 4 B 2 O 9 nanocrystals. When excited at 450 nm, the obtained GCs exhibit a broadband NIR luminescence band covering a spectral region from 650 to 1200 nm. Two different crystallographic sites of Cr3+ in Al 4 B 2 O 9 nanocrystal are considered to account for the observed broadband luminescence. Due to the controllable size and uniformly dispersion of precipitated nanoparticles, this boroaluminosilicate glass-ceramic could find potential applications as monolithic near-infrared light sources in solid-state light emitting devices. [ABSTRACT FROM AUTHOR]

A phase-separated glass is designed to modulate the coordination environments of activators for achieving tunable luminescence in wide wavelength ranges. The luminescent properties and microstructures of Mn2+ doped glasses are carefully investigated. It is found that the luminescence center of Mn2+ is modulated to 620, 588 and 702 nm via the controllable precipitation of K 2 SiF 6 , KZnF 3 and ZnF 2 crystals from the glass networks, respectively. The emissions of Mn2+-Mn2+ dimers centered at 800 nm are also observed when Mn2+ ions are confined in the fluoride crystal coordination environments. The phase-separated glass possesses great potential for providing diverse coordination environments for Mn2+ and is beneficial for the formation of Mn2+-Mn2+ dimers. This glass not only provides a highly promising development of optical gain material for tunable fiber lasers, but the modulation strategy based on phase-separated networks also offers excellent opportunities for manufacturing a wide range of photonic materials featuring multiple-wavelength luminescence. [ABSTRACT FROM AUTHOR]

In current work, transparent fluorosilicate glass-ceramics (GCs) containing NaYF 4 :Er 3+ nanocrystals were successfully prepared by controlled heat treatment process. The thermal properties and crystallization characteristic temperatures were determined by the differential scanning calorimetry (DSC). The X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to confirm the formation of NaYF 4 nanocrystals in glass matrix. Energy dispersive spectrometer (EDS) results and Judd-Ofelt (J-O) parameters analysis demonstrated the incorporation of Er 3+ into NaYF 4 nanocrystals. Intense 2.7 μm luminescence was observed in Er 3+ -doped GCs upon excitation with a 980 nm laser diode (LD). Furthermore, the effect of different alkali metals (Li + , Na + , K + ) on crystallization characteristics and luminescent properties has been studied in detail, which indicates Li + is the most favorable option for mid-infrared luminescence properties compared with Na + and K + . The excellent spectroscopic characteristics suggest that the obtained GCs may be promising materials for mid-infrared fiber lasers. [ABSTRACT FROM AUTHOR]

Divalent europium ions have been widely used as activators in phosphor materials for many applications, which are commonly obtained from the reduction of trivalent europium raw materials. In this work, barium aluminates are chosen as host materials for studying the change of the Eu valence state in glassy and crystal matrices. Eu-doped barium aluminates glass-ceramics are fabricated by containerless processing and subsequent heat treatment. The structural characteristics are observed and the change of Eu valence state is examined. Possible mechanisms of reduction from Eu 3+ to Eu 2+ are discussed. [ABSTRACT FROM AUTHOR]

Transparent nanocrystal-in-glass composite (NGC) comprising functional nanocrystals in transparent inorganic glass creates a new bridging from nano/microscale structure to multifunctional macroscale devices with advanced optical properties. In this review, we outline the key scientific advances in the development of transparent NGC, from the perspectives of fundamental design principles, new synthetic strategies and their substantial progress in advanced optical applications. To generate desired transparent NGC materials, we start with the design principles to describe the transformation process from nano/micro to macro, providing an in-depth insight into the structure-property relationship and the underlying problem in particle binding and network reconstruction in the composite materials. Emerging techniques based on the "top-down" or "bottom-up" strategies have advanced the ability to fabricate nanocomposites with controllable composition, phases, fraction, morphology, spatial distribution, and orientation. We also provide an overview of recent advances in optical applications, including solid-state lighting, high-performance lasers, optical data storage, and fluorescence sensing. The remaining scientific challenges, for example, the important trade-off between functional performance and chemical compatibility when bridging the nanocrystals to transparent NGC and their devices, are also highlighted. Addressing these questions will provide a clear pathway to design and manufacture multifunctional inorganic materials based on these NGC materials. [ABSTRACT FROM AUTHOR]

Abstract: Tm3+–Yb3+ co-doped transparent oxyfluoride glass ceramics were prepared through thermal treatment of the as-prepared glasses. The precipitation of nanocrystals and the incorporation of Tm3+ and Yb3+ into the nanocrystals were confirmed by X-ray diffraction and absorption spectra. Based on the Judd–Ofelt theory, the J–O parameters Ω λ (λ =2, 4, 6), spontaneous radiative transition rates, radiative lifetimes and fluorescence branching ratios of Tm3+ in both as-prepared glasses and glass ceramics were calculated. Intense mid-IR emission and upconversion luminescence in the Tm3+ and Yb3+ co-doped glass ceramics were observed under 980nm excitation. Especially, compared with that of the as-prepared glasses, mid-IR luminescence intensity of Tm3+ in the glass ceramics was greatly enhanced. Desirable spectroscopic characteristics suggest that these oxyfluoride glass ceramics may be promising mid-IR laser active medium. [ABSTRACT FROM AUTHOR]

Abstract: Long lasting phosphorescence has been observed in oxygen-deficient zinc–boron-germanosilicate glass–ceramics after 254nm ultraviolet lights irradiation at room temperature. Electron spin resonance (ESR) spectrum confirms the presence of two paramagnetic centers. And the ESR signal shows a synchronized decay process with afterglow intensity after removing the excitation light, suggesting the afterglow is associated with the paramagnetic centers which are generated during the irradiation. Based on the approximate t −1 decay law of the phosphorescence intensity, the long lasting phosphorescence is attributed to thermal assisted tunneling recombination between pairs of distant electrons and Ge-related oxygen-deficient centers. [Copyright &y& Elsevier]

Abstract: Photoluminescence properties of Sm3+, Dy3+, and Tm3+-doped transparent oxyfluoride silicate glass ceramics containing CaF2 nanocrystals were reported. Emission bands of 4G5/2 → 6H5/2 (562nm), 4G5/2 → 6H7/2 (598nm), 4G5/2 → 6H9/2 (645nm) and 4G5/2 → 6H11/2 (706nm) for the Sm3+: glass and glass ceramic, with an excitation at 6H5/2 → 4F7/2 (402nm) have been recorded. Of them, 4G5/2 → 6H7/2 (598nm) has shown a bright orange emission. With regard to the Dy3+: glass, a bright fluorescent yellow emission at 575nm (4F9/2 → 6H13/2) and blue emission at 481nm (4F9/2 → 6H15/2) have been observed, apart from 662nm (4F9/2 → 6H11/2) emission transition with an excitation at 386nm (6H15/2 → 4I13/2 + 4F7/2) wavelength. Emission bands of 1G4 → 3F4 (650nm) and 1G4 → 3H5 (795nm) transitions for the Tm3+: glass and glass ceramic, with an excitation at 3H6 → 1G4 (467nm) have been observed. Of them, 1G4 → 3F4 (650nm) has shown bright red emission. Decay lifetime measurements were also carried out for all the observed Sm3+, Dy3+, and Tm3+-doped glass and glass ceramic emission bands. [Copyright &y& Elsevier]

Abstract: We report on highly efficient broadband near-infrared photoluminescence (PL) in Ni2+-doped glass ceramics (GCs) films fabricated by annealing Si/Ni2+-doped glass superlattices (SNGS). Over two orders of magnitude enhancement of PL can be achieved in comparison with that from the annealed glass film. The PL lifetime of the annealed SNGS is several milliseconds, which is much longer than those of bulk GCs. The strong PL enhancement results from the formation of high-quality cordierite nanocrystals because the Si layers act as Si source for the crystal growth. This technique can be extended to fabricate other types of high-quality GCs films. [Copyright &y& Elsevier]

Abstract: In this paper, we present the photoluminescence properties of Pr3+-, Sm3+- and Dy3+-doped germanate glasses and glass ceramics. From the X-ray diffraction measurement, the host glass structure was determined. These glasses have shown strong absorption bands in the near-infrared (NIR) region. Compared to Pr3+-, Sm3+- and Dy3+-doped glasses, their respective glass ceramics have shown stronger emissions due to the Ba2TiGe2O8 crystalline phase. For Pr3+-doped glass and glass ceramic, emission bands centered at 530nm (3P0→3H5), 614nm (3P0→3H6), 647nm (3P0→3F2) and 686nm (3P0→3F3) have been observed with 485nm (3H4→3P0) excitation wavelength. Of them, 647nm (3P0→3F2) has shown bright red emission. Emission bands of 4G5/2→6H5/2 (565nm), 4G5/2→6H7/2 (602nm) and 4G5/2→6H9/2 (648nm) for the Sm3+:glass and glass ceramic, with excitation at 6H5/2→4F7/2 (405nm) have been recorded. Of them, 4G5/2→6H7/2 (602nm) has shown a bright orange emission. With regard to the Dy3+:glass and glass ceramic, a bright fluorescent yellow emission at 577nm (4F9/2→6H13/2) has been observed, apart from 4F9/2→6H11/2 (667nm) emission transition with an excitation at 454nm (6H15/2→4I15/2) wavelength. The stimulated emission cross-sections of all the emission bands of Pr3+, Sm3+ and Dy3+:glasses and glass ceramics have been computed based on their measured full-width at half-maxima (FWHM, Δλ) and lifetimes (τ m). [Copyright &y& Elsevier]