Search

The toxicity of heavy‐metal Pb and instability of lead‐based halide perovskite nanomaterials are main factors to impede their practical applications in the fields of solar cells, LEDs and scintillators. In this paper, all inorganic lead‐free cesium manganese halide nanocrystals are synthesized in glass for the first time. Red photoluminescence with broad PL band, negligible self‐absorption and a high photoluminescence quantum yield of 41.8% is obtained. In addition, modulating halide component can change the Mn2+ ions coordination environment to obtain tunable photoluminescence from red to green. More importantly, cesium manganese halide nanocrystals embedded glasses exhibit outstanding long‐term stabilities. Theses cesium manganese halide nanocrystals embedded glasses are also highly stable against high energy irradiation and exhibit highly efficient radioluminescence, making them promising for high‐resolution X‐ray imaging. These results demonstrate that cesium manganese halide nanocrystals embedded glasses are promising eco‐friendly candidates for applications in light‐emitting diodes and scintillators. [ABSTRACT FROM AUTHOR]

Embedding CsPbX 3 (X Cl, Br, I) perovskite nanocrystals (PNCs) into glasses can significantly improve the chemical and thermal properties, and show promising applications in photonic fields. Spatially controlled precipitation of PNCs in glasses is necessary for the fabrication of structured devices. Here, we report that spatially controlled precipitation of CsPbX 3 PNCs in the surface layer of glasses through ion-exchange in molten cesium nitrate salt. Spatial distribution and average diameter of CsPbX 3 PNCs are mainly determined by the distribution of Cs+ and halide ions, and composition of CsPbX 3 PNCs is mainly determined by the composition of host glass. Through ion-exchange, CsPbCl 3−x Br x and CsPbBr 3−x I x PNCs with tunable compositions are precipitated in the surface layer of glasses, and efficient photoluminescence spanning from blue to cyan, green, yellow, orange, and red is realized. Our results demonstrate that ion-exchange is promising to fabricate planar and linear waveguides and various microstructures based on CsPbX 3 PNCs embedded glasses. • CsPbX 3 NCs formed in surface layer of glasses through ion-exchange. • Spatial distribution of CsPbX 3 NCs can be determined by distribution of Cs+. • Composition of CsPbX 3 NCs is mainly determined by composition of the host glass. • The CsPbX 3 NCs in glass surface show efficient and tunable PL in visible region. • Ion-exchange glasses containing CsPbX 3 NCs exhibit clearly planar waveguide effect. [ABSTRACT FROM AUTHOR]

Functional nanoparticles (NPs) hold immense promise in diverse fields due to their unique biological, chemical, and physical properties associated with size or morphology. Microfluidic technologies featuring precise fluid manipulation have become versatile toolkits for manufacturing NPs in a highly controlled manner with low batch-to-batch variability. In this review, we present the fundamentals of microfluidic fabrication strategies, including mixing-, droplet-, and multiple field-based microfluidic methods. We highlight the formation of functional NPs using these microfluidic reactors, with an emphasis on lipid NPs, polymer NPs, lipid-polymer hybrid NPs, supramolecular NPs, metal and metal-oxide NPs, metal–organic framework NPs, covalent organic framework NPs, quantum dots, perovskite nanocrystals, biomimetic NPs, etc. we discuss future directions in microfluidic fabrication for accelerated development of functional NPs, such as device parallelization for large-scale NP production, highly efficient optimization of NP formulations, and AI-guided design of multi-step microfluidic reactors. [ABSTRACT FROM AUTHOR]

Cesium lead halide (CsPbX3, X = Cl, Br, and I) perovskite nanocrystals (NCs) exhibit efficient anti‐Stokes photoluminescence (ASPL) upon sub‐gap single‐photon excitation, which has great potential for all‐solid‐state laser cooling. However, the mechanism responsible for the ASPL still remains elusive. Here, ASPL properties of CsPb(BrI)3 NCs and CsPbI3 NCs in inorganic solid matrix are investigated. Excitation wavelength‐ and power‐dependent ASPL demonstrates that it is a phonon‐assisted single‐photon process. Femtosecond transient absorption spectra show that ASPL is mediated by the Urbach tail states, where localized excitons are generated upon sub‐gap excitation. Through electron–phonon coupling, these localized excitons change into free exciton to generate the exciton bleaching, and then thermally dissociate into free carriers accompanied by band edge bleaching, leading to the efficient ASPL. Such a two‐step up‐conversion process is further confirmed by the carrier temperature extracted from the band edge bleaching band. This work deepens the understanding of ASPL in CsPbX3 NCs, and is valuable for the development of materials for solid‐state laser cooling. [ABSTRACT FROM AUTHOR]

Inorganic perovskite quantum dots (QDs) and nanocrystals (NCs) have attracted much attention in recent years because of their high photoluminescence (PL) quantum yield (QY), narrow full width at half-maximum, and wide tunability across the whole visible range. In this work, space- and size-controlled precipitation of CsPbBr3 perovskite NCs was realized through a femtosecond laser-direct-writing method. Precipitation of CsPbBr3 NCs in glasses was confirmed by energy-dispersive spectroscopy, transmission electron microscopy analysis, and PL. Growth of CsPbBr3 perovskite NCs in glasses was modulated by femtosecond laser irradiation parameters such as the repetition rate, pulse energy, and scanning rate, and PL in the range spanning from blue to green was achieved. With the well-designed arrangement of CsPbBr3 NCs and the reduction of self-absorption emission, a solar concentrator fabricated by femtosecond laser irradiation can realize spectral conversion and enhance the quantum efficiency of solar cells. [ABSTRACT FROM AUTHOR]

Potential of oxide glass‐ceramics containing defect‐fluorite nanocrystals as host matrix for rare‐earth ions for efficient spectral conversion is investigated. The oxide glass‐ceramics embedded with defect fluorite pyrochlore (Eu,Yb)2TiO5 nanocrystals are prepared through melt‐quenching and subsequent heat‐treatment. It turns out that part of Eu3+ and Yb3+ ions are incorporated into the oxide nanocrystals, and Eu3+ ions remained in the glassy phase are reduced into Eu2+ ions. Blue emission from Eu2+ ions, red emission from Eu3+ ions, and near‐infrared emission from Yb3+ ions are generated and modulated by excitation wavelength. These features make oxide glass‐ceramics containing defect‐fluorite (Eu,Yb)2TiO5 nanocrystals promising as host for rare‐earth ions for efficient spectral conversion. [ABSTRACT FROM AUTHOR]

Diamond thin films with a broad range of microstructures from a ultrananocrystalline diamond (UNCD) form developed at Argonne National Laboratory to a microcrystalline diamond (MCD) form have been grown with different hydrogen percentages in the Ar/CH4 gas mixture used in the microwave plasma enhanced chemical vapor deposition (CVD) process. The dielectric properties of the CVD diamond thin films have been studied using impedance and dc measurements on metal-diamond-metal test structures. Close correlations have been observed between the hydrogen content in the bulk of the diamond films, measured by elastic recoil detection (ERD), and their electrical conductivity and capacitance-frequency (C-f) behaviors. Addition of hydrogen gas in the Ar/CH4 gas mixture used to grow the diamond films appears to have two main effects depending on the film microstructure, namely, (a) in the UNCD films, hydrogen incorporates into the atomically abrupt grain boundaries satisfying sp2 carbon dangling bonds, resulting in increased resistivity, and (b) in MCD, atomic hydrogen produced in the plasma etches preferentially the graphitic phase codepositing with the diamond phase, resulting in the statistical survival and growth of large diamond grains and dominance of the diamond phase, and thus having significant impact on the dielectric properties of these films. [ABSTRACT FROM AUTHOR]

Abstract ZnO and ZnO/Zn 2 SiO 4 thin films doped with 3% Eu3+ ions were prepared through sol-gel dip-coating and subsequently thermal annealing in the range of 600–900 °C. Effects of zinc and silica concentration on the structure and optical properties of these thin film specimens were investigated using thermogravimetric differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and emission spectroscopy. Transparent thin films containing ZnO nanocrystals and Zn 2 SiO 4 nanocrystals were fabricated. It was found that Eu3+ ions were mainly resided in the amorphous matrix or the surface of the nanocrystals, instead of being incorporated into the nanocrystals. As a result, these composites showed intense red emission from Eu3+ ions upon 394 nm light emission, and violet emission at ~380 nm upon 266 nm light excitation. Highlights • Composite thin films containing ZnO nanocrystals and Zn2SiO4 nanocrystals were prepared. • Eu3+ ions were not incorporated into crystalline phases. • Dual band emissions at 615 nm from Eu3+ ions and 380 nm from ZnO nanocrystals were observed. [ABSTRACT FROM AUTHOR]

Cooling rate has large effect on the structures and properties of glasses, which may change the chemical, physical, and mechanical properties of glasses, and their crystallization behaviors. In this work, effect of cooling rate on the crystallization and optical properties of glasses, which have been utilized to precipitate semiconductor nanocrystals, are investigated using sodium zinc silicate glasses as typical example. Cooling rate strongly affects the structural connectivity of the glasses, and as a result, Na 8 Al 4 Si 4 O 18 nanocrystals are formed as predominant crystalline phases in glasses with larger cooling rate, and ZnS nanocrystals are formed in glasses with smaller cooling rate. Results reported illustrate that it is important to control the cooling rate of the glass in order to modulate the crystallization and optical properties of semiconductor nanocrystals embedded in glasses. [ABSTRACT FROM AUTHOR]

Ho 3+ /Y 3+ co-doped BaF 2 nanocrystals were precipitated in oxyfluoride glasses through conventional melt-quenching and subsequent thermal treatment. X-ray diffraction patterns, transmission electron microscope images and absorption spectra confirmed the incorporation of Ho 3+ /Y 3+ ions into BaF 2 nanocrystals in glass-ceramics. With the gradual substitution of Ho 3+ ions by Y 3+ ions, concentration dependent energy transfer between excited Ho 3+ ions were suppressed and relative emission intensity at 1.2 μm band was enhanced. The maximum emission cross-section calculated was 0.60 × 10 −20 cm 2 in BH1-GC specimen, indicating that Ho 3+ /Y 3+ co-doped glass-ceramics have a great potential for the development of 1.2 μm band gain medium. [ABSTRACT FROM AUTHOR]

ABSTRACT The interactions between nanoparticles and cells or tissues are frequently mediated by different biomolecules adsorbed onto the surface of nanoparticles. In this study, several methoxy poly(ethylene glycol)-poly(ε-caprolactone) (mPEG-PCL) copolymers with various mPEG/PCL ratios were synthesized and used to produce three types of mPEG-PCL nanoparticles. The protein-adsorption behavior of nanoparticles was assessed using fetal-bovine-serum (FBS) as a model protein. The cell uptake of nanoparticles at different nanoparticle doses as well as various culture periods was examined by measuring their endocytosis rate related to Hela cells cultured in FBS-free and FBS-contained media. The blood clearance of nanoparticles was evaluated using Kunming mice to see the differences in circulation durations of nanoparticles. Results suggest that that FBS is able to significantly regulate the cell uptake of nanoparticles in vitro, and on the other hand, the size and mPEG/PCL molar ratio of mPEG/PCL nanoparticles are closely correlated to their blood clearance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42884. [ABSTRACT FROM AUTHOR]

ZnSe and ZnS nanocrystals (NCs) were precipitated in glasses through heat-treatment. High resolution transmission electron microscope image confirmed that ZnSe NCs were formed in the silicate glasses, and the X-ray diffraction patterns confirmed that ZnS NCs were precipitated in the borosilicate glasses. Absorption shoulders of the ZnSe NCs and ZnS NCs appeared at ~ 2.76 eV and ~ 3.78 eV, corresponding to the bandgap energies of bulk ZnSe and ZnS crystals, respectively. Instead of the intrinsic emissions, broad-band visible photoluminescence from the surface defects or color centers in the glasses was observed from these ZnSe or ZnS NCs. [ABSTRACT FROM AUTHOR]

Er3+ ions-doped germano-gallate oxyfluoride glass-ceramic containing BaF2 nanocrystals was prepared through conventional melt quenching and subsequent thermal treatment method. X-ray diffraction patterns and transmission electron microscope images confirmed the formation of BaF2 nanocrystals in glass-ceramics. Preferential incorporation of Er3+ ions into the BaF2 nanocrystals were confirmed by the absorption spectra and emission spectra, and enhanced upconversion emission and infrared emission were observed. Relatively high transmittance in the mid-infrared region indicated great potential of this germano-gallate oxyfluoride glass-ceramics as host materials for the efficient mid-infrared emission from rare-earth ions. [ABSTRACT FROM AUTHOR]

Infrared emission properties of oxyfluoride glasses with nominal compositions of 55SiO 2 –10Al 2 O 3 –(35 − x − y)PbF 2 –xErF 3 –yYF 3 (in mol%) with x = 0.1, 0.2, 0.3, or 0.5 and y = 0, or 1.0, were investigated. YF 3 was doped into the glasses to overcome the concentration quenching and achieve efficient infrared emission from Er 3 + doped oxyfluoride glass-ceramics. It was found that introduction of YF 3 can efficiently promote the formation of Er 3 + -doped fluoride nanocrystals even when the doping concentration of ErF 3 was low. With the doping of YF 3 , infrared emission was significantly enhanced and strong infrared emissions at 980 nm and 2730 nm bands were observed. Prolongation of lifetimes of Er 3 + : 4 I 13/2 and 4 I 11/2 energy levels showed that concentration quenching of the infrared emissions was greatly suppressed. These results indicate that oxyfluoride glass-ceramics co-doped with Y 3 + have potentials for efficient infrared applications. [ABSTRACT FROM AUTHOR]

Distribution and roles of rare earth ions in fluoride nanocrystals and lead chalcogenide quantum dots formed in glasses are reported. High-resolution transmission electron microscopic analysis and electron energy loss spectroscopic ( EELS) analysis showed that oxyfluoride glasses initially form crystals with high Er3+ content such as PbErF5 during heating and gradually form crystals with low Er3+ concentration. Amount of PbErF5 crystals depended upon the initial concentration of Er3+ ions in the parent glasses. EELS analysis also showed that Nd3+ ions were formed inside PbS quantum dots, supporting the proposition of the formation of Nd-O clusters. [ABSTRACT FROM AUTHOR]

The treatment of Alzheimer's disease (AD) has been hampered by a lack of sensitive and specific non-invasive diagnostic methods. Quantum dots (QD) are nano-crystals with unique photo-physical properties that bypass some of the limitations of conventional dyes and imaging tools. This study is aimed to evaluate the fluorescence properties of a QD probe conjugated with an anti-Aβ antibody (QD-Aβ-Ab). Healthy mice and mice bearing mutated human APP695swe and APP717 V- F transgenes received intracerebroventricular injection of the probe for subsequent imaging. Immunohistochemistry revealed that Aβ was distributed in the hippocampus CA1 area in the APP transgenic mice. Fluorescence microscopy demonstrated that fluorescence was mainly observed in the hippocampus area, the cerebral cortex, sagittal septum and striatum of APP transgenic mice. In vivo imaging of mice receiving the QD-Aβ-Ab probe showed that healthy mice exhibited a narrow range of fluorescence and lower fluorescence intensity compared with APP transgenic mice. The mean fluorescence intensity of brain tissues of healthy C57BL mice was 12.3784 ± 3.9826, which was significantly lower than that of 10- and 16-month-old APP transgenic mice (45.03 ± 2.66 and 46.69 ± 3.22, respectively; P < 0.05). In this study we present the first direct evidence that QD-Aβ-Ab conjugate probes can track in vivo state of Aβ accumulation in mice and the findings suggest that such probes may be of potential use for early molecular diagnostic imaging of AD. [ABSTRACT FROM AUTHOR]

Abstract: Er3+-doped lead fluoride nanocrystals (NCs) were precipitated in glasses by heat treatment at 490°C, and the distribution of Er3+ ions inside the NCs was investigated using electron energy loss spectroscopy. Nucleation started with the formation of 2–4-nm-diameter NCs highly enriched in Er3+. With further heat treatment, NCs with inhomogeneous Er3+ distribution grew. Crystal structure in individual fluoride NCs changed from tetragonal to cubic due to the variation in Er3+ concentration. [Copyright &y& Elsevier]

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: Optical properties and photoluminescence of PbS quantum dots (QDs) embedded in glasses were investigated. Formation and radius of PbS QDs were carefully controlled though heat-treatment and modification of host glass composition. Heat-treatment conditions for precipitation of 3–10nm radius QDs for the tunable photoluminescence in the 1–2μm wavelength range were identified. Glasses doped with PbS QDs provide potential as robust materials for broadband fiber-optic amplifiers. [Copyright &y& Elsevier]

The construction of highly efficient photocatalysts for generating high-purity hydrogen (H 2) through a sustainable water decomposition system is a feasible option to replace conventional non-renewable energy resources. Here, we report a simple chemical reduction approach to embed Cu–Pt alloy nanocrystals on the C 3 N 5 (CN) matrix, creating a Schottky heterojunction. The structural morphology, crystal phase, light-harvesting capacity, and photo-electrochemical properties of as-prepared heterostructures were investigated. The uniformly anchored Cu–Pt alloy nanocrystals improve the photocatalytic H 2 evolution (PHE) activity by promoting the separation and transfer of photogenerated carriers and inhibiting recombination. Meanwhile, the alloyed nanocrystals strengthen the absorption of incident light energy, inducing photothermal energy. This improves the charge carrier separation and promotes the surface reaction kinetics. The PHE performance of as-developed catalysts could be adjusted by optimizing the molar ratio of Cu/Pt ions. Among them, the optimal Cu 1 Pt 3 /CN photocatalyst yields a higher PHE performance (672.85 μmol g−1 h−1). Notably, the Cu 1 Pt 3 /CN catalyst also reveals an enhanced photocatalytic activity for H 2 evolution in natural seawater. The possible PHE mechanism in CuPt/CN heterostructures is discussed toward the role of CuPt alloy deposition in boosting photocatalytic efficiency. Cu–Pt alloy nanoparticles/C 3 N 5 nanosheets composites exhibited excellent solar photocatalytic hydrogen evolution ability due to high charge carrier separation efficiency and outstanding inhibition ability for the separation of electron hole pairs. [Display omitted] • Electronic structure of C 3 N 5 was regulated by Cu – Pt alloy loading. • Cu – Pt/C 3 N 5 composites were prepared for PHE. • Cu 1 Pt 3 /CN exhibited the better PHE performance in natural seawater. • The PHE mechanism of Cu 1 Pt 3 /CN was proposed. [ABSTRACT FROM AUTHOR]

Abstract: PbSe quantum dots (QDs) were synthesized in borosilicate glass and their optical properties were investigated. The typical quantum confinement effects were clearly observed from the absorption when the average radii of the QDs changed from 1.7 to 3.1nm. Photoluminescence from PbSe QDs was achieved in 1.1–2.2μm wavelength region that covers the entire fiber-optic telecommunication window. Borosilicate glasses containing controlled size of PbSe QDs provide potentials for the fiber-optic amplifiers. [Copyright &y& Elsevier]

Introducing of impurity ions into semiconductor nanocrystals can improve their photoluminescence quantum efficiency through energy transfer and enhance their applicability towards light-emitting devices. In this work, Mn doped CsPbCl 3 and CsPbCl 3-x Br x perovskite nanocrystals were prepared in glass through melt-quenching and subsequent thermal treatment. Both Mn doping concentration and thermal treatment conditions affected the growth and resultant band edge emission of perovskite nanocrystals, enabling tunable photoluminescence ranging from UV to blue. In addition to UV-blue band edge emission from these Mn-doped perovskite nanocrystals, red emission from Mn ions was activated through efficient energy transfer from perovskite nanocrystals. Intensity ratio between the band edge emission of perovskite nanocrystals and red emission of Mn ions was also tunable by varying the Mn doping concentration and heat-treatment conditions, covering a wider color gamut. Along with the good chemical and mechanical properties of glass matrix, these Mn-doped cesium lead halide perovskite nanocrystal embedded glasses have potentials for applications in light emitting devices. • Mn doped CsPbCl 3 and CsPbCl 3-x Br x perovskite nanocrystals were prepared in glass. • Mn2+ emission was enhanced through efficient energy transfer from perovskite nanocrystals. • Intensity ratio between exciton emission and Mn2+ emission was tunable. [ABSTRACT FROM AUTHOR]

As a wide band gap semiconductor, alkaline-earth metal sulfides (AES) with low phonon energy, high laser damage threshold, and high transmittance in infrared, have wide application prospects in bioimaging, spectral conversion, and solid-state lighting. However, AES nanocrystals (NCs) suffer from the weak chemical-stability and low mechanical-stability, and can be easily oxidized in humidity and oxygen. Incorporation of AES NCs into inorganic glass is expected to overcome those inherent limitations. In this work, a new type of oxysulfide glass-ceramics containing CaS, SrS, BaS, Sr x Ba 1−x S, and Ca x Sr 1−x S NCs is developed, and average diameters of these AES NCs are tuned in the range of 3–18 nm. Precipitation of AES NCs not only improves the mechanical properties of glass, but also maintains high transmittance (˃60%) in the spectral range of 1–4.3 µm. Results reported in this work offer a new pathway for developing novel oxysulfide glass-ceramics for multi-functional optical devices. [ABSTRACT FROM AUTHOR]

Cesium lead halide (CsPbX3) nanocrystals have great potential for photovoltaic and optoelectronic applications, but they are sensitive to oxygen, moisture, and light irradiation. Embedding these CsPbX3 nanocrystals into all‐inorganic amorphous solid matrices such as glass is expected to improve their stability. In this work, CsPbX3 nanocrystals are precipitated in boro‐germanate glasses with tunable composition, absorption, and photoluminescence. Quantum efficiency of CsPbBr3 nanocrystals in glass can be as high as ≈80% and ≈20% for CsPb(Cl/Br)3 and CsPb(Br/I)3 nanocrystals, respectively. Thermo‐ and photostabilities of CsPbX3 nanocrystals in glass are greatly improved due to the inert nature of glasses, and intense laser irradiation‐induced damage to CsPbX3 nanocrystals is recoverable through thermal annealing. With CsPbBr3 nanocrystal‐embedded glass slices, a green light‐emitting device with a luminous efficiency of ≈120 lm W−1 and an external quantum yield of ≈30% is achieved. A white‐light‐emitting device consisting of CsPbBr3 nanocrystals and CsPb(Br/I)3 nanocrystal–embedded glass slices shows luminous efficiency in the range of 50–60 lm W−1 and external quantum yield of 20–25%. The thermo‐ and photostabilities along with the chemical stability of CsPbX3 nanocrystal–embedded glasses are promising materials for photoluminescence related applications. [ABSTRACT FROM AUTHOR]

Topotactic anion exchange has been developed to tune the composition and band gap energies of cesium lead halide (CsPbX3) perovskite nanocrystals (NCs). However, current anion exchange methods either require harsh conditions or take a long time to realize substantial substitution. Here, we present a method to modulate the composition of colloidal CsPbBr3 NCs through ultrasonication-assisted anion exchange with CsX (X = Cl, I) solution. Efficient anion exchange of CsPbBr3 NCs with Cl− or I− is realized with substitution ratio up to 93% and preservation of the pristine shape and structure of CsPbBr3 NCs. This anion exchange results in tunable emission, covering the whole visible spectral range, with relatively high photoluminescence quantum yield, narrow emission bandwidths, and good stability. This work provides a facile and efficient way to engineer the properties of halide perovskite NCs and has great potential for large-scale production of compositionally diverse perovskite NCs. [ABSTRACT FROM AUTHOR]

Ion-exchange has been widely employed to modify the composition and structure of glasses. In this work, Cs–K ion-exchange was carried out to facilitate the precipitation of cesium lead halide perovskite nanocrystals in the surface layer of glasses. Both Cs 4 PbBr 6 and CsPbBr 3 perovskite nanocrystals and KBr nanocrystals can be precipitated through ion-exchange in nitrate salt. Content of Cs 4 PbBr 6 and CsPbBr 3 perovskite nanocrystals is strongly dependent on the composition of nitrate salt, ion-exchange conditions, and post-thermal annealing. High concentration of Cs in nitrate salt, long ion-exchange duration, and post-thermal annealing are effective to promote the formation of CsPbBr 3 perovskite nanocrystals. Results reported is valuable for the developing of cesium lead halide perovskite nanocrystals embedded glass for light converters. [ABSTRACT FROM AUTHOR]

• High transparent and colorless Zn 2 TiO 4 glass-ceramics are prepared. • Zn 2 TiO 4 glass-ceramics show effective photo-catalytic properties. • Zn 2 TiO 4 glass-ceramics possess high mechanical and chemical stability. • The photo-catalytic properties of Zn 2 TiO 4 glass-ceramics are recyclable. Photo-catalytic active glass-ceramics have good application prospects in addressing environmental problems and offer advantages over traditional photo-catalyst. Photo-catalytic properties of glass-ceramics mainly depends on the presence of photo-catalytic active nanocrystals embedded inside. Zn 2 TiO 4 , as a stable intermediate phase of TiO 2 -ZnO system, has comparative photo-catalytic activities with traditional photo-catalyst TiO 2 and ZnO. In this work, colorless and highly transparent glass-ceramics containing Zn 2 TiO 4 nanocrystals are successfully prepared, and effects of crystallization on microstructure, mechanical, photo-catalytic and recyclable properties are investigated. These Zn 2 TiO 4 nanocrystals embedded glass-ceramics are found to be photo-catalytically active and efficient in photo-degradation of organic dyes. These results show that glass-ceramics containing photo-catalytic nanocrystals are promising for degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

Transparent glass-ceramics have particular properties compared with their precursor glasses, and have promising potential applications in many fields. Titanium-relative phases are frequently employed as nucleation agents for crystallization of glass-ceramics, and rarely been precipitated as functional nanocrystalline phases in glass-ceramics. In this work, transparent glass-ceramics containing Zn 2 TiO 4 and/or α-Zn 2 SiO 4 nanocrystals are investigated. It turns out that Vickers hardness of these glass-ceramics increases with the precipitation of Zn 2 TiO 4 and α-Zn 2 SiO 4 nanocrystals. Despite the blocking effect of nanocrystals precipitated in the glass-ceramics, structural and compositional modification of the residual glass induced by the precipitation of these nanocrystalline phases facilitates the K-Na ion-exchange, leading to the enhanced depth of layer and further improved Vickers hardness of the glass-ceramics. [ABSTRACT FROM AUTHOR]

CsPbBr 3 perovskite nanocrystals (NCs) have been recognized as promising candidates for optoelectronic applications. However, the poor stability of CsPbBr 3 NCs under humid and thermal conditions, which has a substantial influence on their photostability, hinders their long-term utilization. Embedding these CsPbBr 3 NCs in glass is expected to improve their stability. In this work, Sr2+- doped CsPbBr 3 NCs are precipitated in boro-germanosilicate glasses and the PL bands were tuned by changing heat-treatments and Sr2+ doping concentrations covering the wavelength range of 507–524 nm. The maximum PL quantum efficiency of Sr2+-doped CsPbBr 3 glass is 74.2% with the Sr2+/Pb2+ ratio of 3:7 at 480 °C/10 h. And the PLQY of this sample further increased to 81.7% after 60 days storage. The Sr2+ -doped CsPbBr 3 NCs also exhibits better thermal stability than the undoped CsPbBr 3 NCs because the Sr2+ ions passivated surface defects and reduced non-radiative transitions. The good thermal and water resistance of Sr2+ -doped CsPbBr 3 NCs allow the potential applications in high-performance optical devices. [ABSTRACT FROM AUTHOR]

Nd 3 + and Tm 3 + , doped oxy-fluoride glasses and glass ceramics were prepared by conventional melt-quenching and subsequent heat-treatment, respectively. β-PbF 2 nanocrystals with diameter 50 –100 nm formed in the glass matrix after heat treatment. The Stark splitting in absorption peaks, enhanced photoluminescence and prolonged lifetimes that β-PbF 2 nanocrystal formation increased the luminescence of rare earth ions. Both Nd 3 + and Tm 3 + ions were incorporated into nanocrystals that were enriched in lead and fluorine, and deficient in oxygen. [ABSTRACT FROM AUTHOR]

In this work, PbSe QDs were precipitated in oxyfluoride glass-ceramics containing BaF2 nanocrystals. Tunable and broad absorption and photoluminescence from PbSe QDs doped glass-ceramics were observed in the near-infrared wavelength range. When the glasses were heat-treated at temperatures below 560°C using one-step heat-treatment schedule, single photoluminescence band was observed from each sample. Upon high temperature (560°C or 570°C) one-step or two-step heat-treatment, dual-band photoluminescence was observed. These two photoluminescence bands in each spectrum were separated by a gap of ~110–150meV, and as a result, effective full width at half maximum as large as ~500nm was recorded. [ABSTRACT FROM AUTHOR]

• Glass-ceramics containing ZnAl 2 O 4 and β-quartz solid solution nanocrystals were prepared. • Compared with the specimen with simultaneous precipitation of ZnAl 2 O 4 and β-quartz solid solution nanocrystals, glass-ceramics with sequential crystallization of ZnAl 2 O 4 and β-quartz solid solution nanocrystals show smaller grain size and more uniform structure and higher transparency. • Ion-exchange depth of layer increased significantly with the crystallization, which was related to the reduction in content of zinc and five coordinated aluminum in the residual glass matrix. • It was found that ionexchange process took place at the boundaries between nanocrystals and glass matrix, which was also considered to be responsible for the enhanced depth of layer. Crystallization of glass has significant effects on glass structure and the resultant ion-exchange behaviors. In this work, transparent glass-ceramics (GCs) with sequential crystallization of ZnAl 2 O 4 and β-quartz solid solution nanocrystals (NCs) were prepared, and effects of the crystallization on microstructure and ion-exchange properties were investigated. Compared with the specimen with simultaneous precipitation of ZnAl 2 O 4 and β-quartz solid solution NCs, GCs with sequential crystallization of ZnAl 2 O 4 and β-quartz solid solution NCs show smaller grain size and more uniform structure and higher transparency. Ion-exchange depth of layer (DOL) increases significantly with the crystallization of the specimens due to the reduction in content of zinc and five coordinated aluminum in the residual glass matrix. High residual compressive stress and Vickers hardness can be obtained after ion-exchange in KNO 3 molten salt. [ABSTRACT FROM AUTHOR]

Controlled nanocrystallization of glasses is prerequisite for developing transparent glass-ceramics with functionalities that determined by precipitated nanocrystals and residual glassy matrix. However, simultaneously control of nanocrystal phase and size in glasses has not yet been achieved. Herein, we introduce a modified chalcogenide flux protocol to precisely design metal halide (MX) nanocrystals in glassy matrices. The size and amount variation of MX nanocrystals were quantified with thorough microscopic analysis, demonstrating the growth of MX nanocrystals occurs with the depletion of smaller ones. We reveal an Ostwald-ripening controlled nanocrystallization mechanism for simultaneously controlling over the crystal phases and crystal growth of MX precipitates in chalcogenide glassy matrices. These results not only show a new fact for understanding the nature of glass formation and crystallization, but also provide a simple and convenient route to robust glass-ceramic materials embedded with a variety of MX nanocrystals for novel photonic applications. [ABSTRACT FROM AUTHOR]

The interactive figure to visualize this research results. [Display omitted] • Revealing the passivation mechanism of excess Br on CsPbBr 3 NCs in glasses. • Investigating the photo-induced structural and optical changes of CsPbBr 3 NCs in glasses. • Demonstrating the fatal effect of photodamage on laser application of CsPbBr 3 NCs. • Guiding the regulating photostability through Br concentration for application on light-emitting diodes and information storage. Cesium lead halide perovskite nanocrystals have particular optoelectronic properties and important applications in various fields. Embedding cesium lead halide perovskite nanocrystals into glass matrices have improved their thermal and chemical stabilities. However, these cesium lead halide perovskite nanocrystals in glasses are still sensitive to intense light irradiation, limiting their wide applications. In this work, fs laser irradiation on the structural and optical properties of cesium lead bromide (CsPbBr 3) perovskite nanocrystals (PNCs) is investigated. It turns out that fs laser irradiation does not change the structural skeletons and band gap energies of CsPbBr 3 PNCs in glasses, but induces surface Br vacancies. In-situ transient absorption spectral analysis reveals one <10 ps trapping process of photo-generated carriers after fs laser irradiation, and confirms that Br vacancies are induced by Br migration driven by photo-generated carriers. In addition, CsPbBr 3 PNCs with high PL QY in glasses through Br passivation can be more easily damaged by fs laser, making it difficult to achieve stable stimulated emission towards laser application. These results shine light on the effect of halogen contents on the photo-stability of cesium lead halide PNCs and the regulation of cesium lead halide PNCs embedded glasses for photo-electronic applications. [ABSTRACT FROM AUTHOR]

In this work, effect of the Yb 2 O 3 doping on the structure and spectroscopic properties of zinc aluminate nanocrystals formed in the glasses were investigated. Zinc aluminate nanocrystals were precipitated in the glasses through heat-treatment. X-ray diffraction, transmission electron microscopy and absorption spectroscopy were utilized to characterize the structural and spectroscopic properties. It was found that pure ZnAl 2 O 4 spinel nanocrystals were formed in the glasses without Yb 2 O 3 doping. As the doping concentration of Yb 2 O 3 increased, Yb 3 + ions were incorporated into the zinc aluminate nanocrystals and gradually changed the structure of space group of zinc aluminate from Fd 3 − m to F432. Both elemental mapping and absorption spectroscopy confirmed the incorporation of Yb 3 + ions into the nanocrystals formed in the glasses. [ABSTRACT FROM AUTHOR]

This paper reported on preparation technique, fluidity mechanism and significant characteristics of covalent nanocrystals-decorated solvent-free graphene oxide liquids (CN-GOLs), which were achieved through the introduction of nanocrystals onto the surface of graphene oxide (GO), and then by surface chemical engineering of the nanocrystals-decorated graphene oxide (N-GO) with organosilanes as corona and polyether amine as canopy. Structural characterization, rheology behavior and significant characteristics of CN-GOLs were investigated by Fourier transform infrared spectroscopy, Transmission electron microscopy and Rheometer, as well as X-ray photoelectron spectroscopy and Vibrating sample magnetometer, respectively. Subsequently, a slipping and fluidity model was carefully established to better understand the fluidity mechanism of CN-GOLs. Both of experiment results and fluidity mechanism demonstrated that the introduction of nanocrystals onto the surface of GO was a facile and efficient method to synthesize CN-GOLs with lower price and simpler procedures. Most importantly, such a preparation technique could be further extended to the fabrication of other types of CN-GOLs with attractive properties for specific applications, such as filler phase for resin-matrix composites. [ABSTRACT FROM AUTHOR]

• PLQY of CsPbBr 3 NCs embedded glass are boosted to over 90%. • Green LEDs based on CsPbBr 3 NCs embedded glasses show EQE of 33.72%. • WLEDs based on CsPbBr 3 NCss in glass and red phosphor show LE of 166.88 lm/W. • Color gamut of the white LED is found to be 132.5% of NTSC and 99.2% of Rec. 2020. All inorganic cesium lead halide perovskite nanocrystals have great potential for electrically pumped or optically pumped light emitting diodes. External quantum efficiency of electrically pumped perovskite nanocrystals-based light emitting diodes are strongly affected by the imbalanced charge injection, electric field induced ion diffusion and joule heating. External quantum efficiency of optically pumped perovskite nanocrystals-based light emitting diodes are also affected by their photo-stability and photoluminescence quantum efficiency. Here, highly efficient light-emitting diodes are realized by employing CsPbBr 3 nanocrystals embedded glasses as color converter. It is found that increase in molar ratio between bromine and lead in glasses results in the passivation of bromine vacancies of CsPbBr 3 nanocrystals, and significantly improves photoluminescence quantum efficiency and photo-stability of CsPbBr 3 nanocrystals embedded glasses. With these CsPbBr 3 nanocrystals embedded glasses as color converter, highly efficient green light-emitting diodes with external quantum efficiency of 33.72% and white light-emitting diodes with external quantum efficiency of 43.27% are realized. These results demonstrate that cesium lead halide perovskite nanocrystals embedded glasses are promising for optically pumped light-emitting diodes. [ABSTRACT FROM AUTHOR]

Pb 1-x Sr x Se quantum dots (QDs) were prepared in Li 2 O-Al 2 O 3 -SiO 2 (LAS) glass-ceramics with 0–2.0 mol% SrO by conventional melt-quenching method. The near-infrared photoluminescence and photodarkening properties of Pb 1-x Sr x Se QDs in LAS glass-ceramics were studied. Upon the heat treatments of 490–550 °C for 10 h, there are LiAlO 2 nanocrystals and PbSe QDs co-existed in the glassy matrix without SrO, and 1024–1745 nm near infrared emission from PbSe QDs were realized. With the increasing of SrO concentration from 0 to 2 mol%, the absorption wavelengths blue-shifted from 1738 to 1380 nm at 540 °C, the PL peak wavelengths blue-shifted from 1788 to 1538 nm at 540 °C. The blue-shifts are attributed to the increasing bandgap by incorporation of Sr2+ ions into PbSe crystalline lattice. Pb 1-x Sr x Se QDs display better photoinduced anti-darkening properties than pure PbSe QDs with the increasing of pumping power, and the Pb 1-x Sr x Se QDs embedded in the LAS glass with 2.0 mol% SrO shows the highest photoluminescence quantum yield of ∼36.9%. [Display omitted] [ABSTRACT FROM AUTHOR]

Luminescent solar concentrators (LSCs) have important application in building integrated photovoltaic. CsPbX 3 (X = Cl, Br, I) perovskite nanocrystals possessing tunable band gap energies, large absorption coefficients, narrow band photoluminescence (PL), and high photoluminescence quantum yield (PL QY), have great potential application in LSCs. However, instability of perovskite nanocrystals in ambient environment still limits their practical application. Herein, as a proof-of-concept experiment, CsPbBr 3 nanocrystal-embedded glass sheets with various geometric factors are investigated as LSCs. Due to the wide absorption spectral range, high PL QY, and narrow PL, optical efficiency of 6.17% (2 × 2 cm2) is achieved from LSCs based on CsPbBr 3 nanocrystal-embedded glass sheets. Importantly, the stability tests show that the glass matrix can effectively protect CsPbBr 3 nanocrystals from eroding of ambient environment. These results show that CsPbBr 3 nanocrystal-embedded glasses are promising materials for LSCs. [Display omitted] • CsPbBr 3 nanocrystal-embedded glasses with PL QY exceeding 80% was prepared. • The glass matrix shows extraordinary stability. • Luminescent solar concentrators based on CsPbBr 3 nanocrystal-embedded glasses are reported. • Optical efficiency of 6.17% (2 × 2 cm2) is realized from LSC. [ABSTRACT FROM AUTHOR]

Abstract: Chalcohalide glass with a composition of 65GeS2–25Ga2S3–10CsI (in mol%) doped with 0.6wt% Tm3+ ions was prepared by conventional melt–quench method. By heat treating the precursor glass at 20°C above its glass transition temperature T g for different durations, IR transparent glass ceramics were obtained. X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that Ga2S3 crystallites were precipitated after heat treatment and their grain sizes were in nano-scale and increased with the elongation of heat treated time. Mid-IR luminescence properties of the glass and transparent glass ceramic samples were investigated. The emissions at 2.3 and 3.8μm corresponding to optical transitions of 3 H 4 → 3 H 5 and 3 H 5 → 3 F 4 of Tm3+ ions were significantly enhanced by the presence of Ga2S3 nanocrystals and reached a maximum after 8hours treatment. [Copyright &y& Elsevier]

Abstract: Superparamagnetic iron oxide nanocrystals (SPION) and their colloidal solutions of magnetic nanoparticles (ferrofluid) appear to contribute to the magnetite imaging applications. Here we present an aqueous ferrofluid in physiological pH and its cell tracking potential. In situ coating method was adapted to synthesize N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC)-coated SPION. Characterization results reveal their features as follows: (1) z-average diameter of 274.1±1.934nm; (2) polydispersity index (PDI) of 0.135±0.029; (3) zeta potential of 11.4±0.410mV; (4) iron concentration of 5.4mg Fe/ml; (5) stable in both water and normal saline; (6) uptake by a variety of cell lines and (7) little cytotoxicity. Finally, islet grafting experiments demonstrated the potential usefulness of this product as a MRI contrast agent for cell tracking. [Copyright &y& Elsevier]

Abstract: Nanocrystalline Fe–40Al–5Cr powders were synthesized by mechanical alloying (MA) of the Fe, Al elemental powders and the Fe–20Cr prealloyed powders. Structural evolutions, morphologies, composition homogenization and ordering transformation of the Fe–40Al–5Cr powders during MA and subsequently heat treatment were studied. In the early stage of MA (<15h), solid solutions of Fe(Al) and Fe–Cr(Al) form through Al diffusing into Fe and Fe–20Cr, respectively. Layered Fe(Al)/Fe–Cr(Al) laminae are the typical structure of the milled powders. On prolonging the milling time from 15 to 70h, the layered laminae disappear, and the milled powders turn to be dense, fine and spherical. Meanwhile, the composition homogenization of the milled powders is also gradually accomplished. After the Fe–40Al–5Cr powders milled for 70h, nanocrystalline Fe(Al, Cr) powders form with a homogeneous composition. During heating the milled powders from room temperature to 600°C, the ordering transformation from Fe(Al, Cr) to B2-FeAl(Cr) occurs. The Cr content in the Fe–40Al–5Cr powders was found to hinder the composition homogenization and ordering transformation of the powders during MA and subsequent heat treatment. [Copyright &y& Elsevier]

● Multicomponent nanocrystalline W‒Cu based composite was fabricated by an in-situ reaction strategy. ● Hardness and wear resistance were remarkably enhanced compared to conventional binary coarse-grained counterpart. ● Mechanisms of wear resistance consist of nanostructure, strain gradients and crystallographic relationship at interfaces. As compared to the conventional binary coarse-grained W‒Cu composite, the multicomponent nanocrystalline W‒Cu based composite fabricated by a specially designed in-situ reaction process exhibits fourfold hardness and twofold wear resistance. The enhancements of the properties are attributed to the refined nanostructure, strain gradients induced by the Cr and WC hard nanoparticles, and well-aligned crystallographic orientation relationship and atomic correspondence at phase and grain boundaries in the composite even at the severe deformation state. ga1 An in-situ reaction strategy to synthesize W‒Cu based nanocomposite co-doped with Cr and WC was proposed, and the resultant multicomponent nanocrystalline bulk has a homogeneous distribution of various phases. As compared to the conventional coarse-grained W‒Cu composite, the prepared nanocrystalline W‒Cu based composite exhibits fourfold hardness and twofold wear resistance. The enhancement of the wear resistance is attributed to the restricted formation and delamination of the mechanically mixed layer and the increased strain gradient induced by the hard phases on the worn surface. The formation of the refined nanostructure with well-aligned crystallographic orientation relationship results in significant hardening of the worn surface. The present work opens up new opportunities to achieve superior hardness and wear resistance of metal matrix composites based on design and fabrication of multicomponent nanostructures. [ABSTRACT FROM AUTHOR]

• Pyrochlore structured nanocrystals were precipitated in glass. • Rare-earth ions were efficiently incorporated into pyrochlore nanocrystals. • Efficient visible and near-infrared emission was observed. Pyrochlore structured nanocrystals could have large solubility of rare-earth ions, making them promising for application in various light emitting materials and immobilization of radioactive nuclear waste. In this work, rare-earth doped pyrochlore structured nanocrystals were precipitated in glasses using melt-quenching and subsequent thermal treatment. Lu3+ along with Yb3+ and Er3+ ions were doped into the glasses, and Yb3+ and Er3+ were employed as probes to illustrate the incorporation of rare-earth ions into pyrochlore nanocrystals. X-ray diffraction patterns and transmission electron microscopy showed the precipitation of pyrochlore nanocrystals with average diameters of 13–15 nm upon thermal treatment. Energy dispersive spectroscopy, absorption spectra, visible and near-infrared emission spectra all confirmed the incorporation of rare-earth ions into these pyrochlore structured nanocrystals. [ABSTRACT FROM AUTHOR]

Fe:Co:ZnSe nanocrystals with different co-doping ratios of Fe2+/Co2+ ions were fabricated by hydrothermal synthesis. The facile method used in the present work avoids the mid-infrared quench effect induced by the organic molecular introduced in the past preparation process. These nanocrystals are spherical in shape and exhibit a cubic sphalerite structure with an average grain size of about 15 nm. Through the energy conversion between Co2+ and Fe2+ ions, mid-infrared fluorescences at 3.3 μm and 4.4 μm were detected under 1550 nm laser excitation at room temperature. The fluorescence band of 4.4 μm in the Fe:Co:ZnSe nanocrystals is thought to be an overlapping emission involving the peak centered at 4648 nm corresponding to the Co2+:4T 1 (F) → 4T 2 (F) energy transition and the peak centered at 4273 nm corresponding to Fe2+:5T 2 (D) → 5E (D) energy transition. These high-quality optically active nanomaterials show potential applications in mid-infrared devices such as composite fiber-amplifiers and lasers materials. • A serial Fe:Co:ZnSe nanocrystals were synthesized via hydrothermal method without organic ligand. • The emission at 4273 nm was detected in the Fe:Co:ZnSe nanocrystals at room temperature. • The 0.6 mol % Fe 3 mol % Co: ZnSe nanocrystals exhibit the strongest fluorescence. [ABSTRACT FROM AUTHOR]