Recently, adopting carbon coating has drawn considerable attention for increasing the electrical conductivity and enhancing the stability of the electrode materials as elastic buffer supports upon cycling to improve the electrochemical performance. [27][28][29][30][31] Even through the volume changes may be effectively controlled by flexible substrates, this strategy is still limi ted in improving specific capacity and rate performance. Nanoengineering of ultrafine nanostructure (ultrafine nanoparticles or ultrafine nanosized subunits) has become the most powerful mean to tackle above challenge because they can increase the electrodeelectrolyte contact area, lower the absolute volume change, and shorten the distance for lithium-ion diffusion within the particles. [32,33] For instance, 3D mesoporous Co 3 O 4 networks composed of small Co 3 O 4 nanoparticles (5-10 nm) synthesized by Naiqin Zhao exhibit high specific capacity (1033 mA h g −1 at 0.1 A g −1 ) and remarkable rate capability. [34] Furthermore, robust and favorable ultrafine secondary nanoparticles would effectively accommodate the severe volume variation upon cycling and prevent self-aggregation of the ultrafine nanoscale subunits, thus leading to improved capacity retention and rate capability. For example, polydopamine-coated SnO 2 nanocrystals comprising SnO 2 nanoparticles (diameter ≈ 5 nm) developed by Lin and co-workers display excellent rate capability. [35] Nevertheless, the existing synthetic methods can only fabricate the ultrafine nanoparticles with exposed or mosaic structure which have disadvantages of inevitable aggregation and unstable nanostructure during long-term cycling; moreover, they are unsuitable for large-scale production. Hence, it is a great challenge to design and synthesize ultrafine carbon coating TMO subunit through a facile and one-pot method on a large scale.Along these lines, we develop a facile and novel one-pot approach for the first time to synthesize a series of highly uniform pomegranate-like TMO@nitrogen-doped carbon nanoclusters (TMO@N-C NCs) with a large scale production, which are organized by numerous of ultrafine TMO@N-C subunits (diameter ≈ 4 nm). This approach has been demonstrated to synthesize various pomegranate-like TMO@N-C NCs, including simple oxides such as Fe 3 O 4 , Mn 3 O 4 , NiO, and ZnO. Taking pomegranate-like Fe 3 O 4 @N-C NCs as an example, the pomegranate-like Fe 3 O 4 @N-C NCs with this unique nanostructure show excellent cycle stability and superior rate capacity Uniform pomegranate-like nanoclusters (NCs) organized by ultrafine transition metal oxide@nitrogen-doped carbon (TMO@N-C) subunits (diameter ≈ 4 nm) are prepared on a large scale for the first time through a facile, novel, and one-pot approach. Taking pomegranate-like Fe 3 O 4 @N-C NCs as an example, this unique structure provides short Li + /electron diffusion pathways for electrochemical reactions, structural stability during cycling, and high electrical conductivity, leading to superior electrochemical performance. The resulting...

Selective doping of Ni2+ in octahedral sites provided by nanocrystals embedded in glass-ceramics (GCs) is crucial to the enhancement of broadband near-infrared (NIR) emission. In this work, a NIR emission with a full-width-at-half-maximum (FWHM) of 288 nm is first reported from ZnGa2O4: Ni2+ nano-spinels embedded GCs with excellent transparency. A comparison is made of the NIR luminescence properties of Ni2+ doped GCs containing ZnGa2O4, germanium-substituted ZnGa2O4 nano-spinels (Zn1+xGa2−2xGexO4), and Zn2GeO4/Li2Ge4O9 composite nanocrystals that are free of Ga3+. The results show that ZnGa2O4: Ni2+ GCs exhibit a significantly enhanced NIR emission. The incorporation of the nucleating agent TiO2 is favored in terms of the increased luminescence intensity and prolonged lifetime. The possible causes for the enhancement effect are identified from the crystal structure/defects viewpoint. The newly developed GCs incorporate good reproducibility to allow for a tolerance of thermal treatment temperature and hence hold great potential of fiberization via the recently proposed “melt-in-tube” method. They can be considered as promising candidates for broadband fiber amplifiers.

Selective doping of optically active ions into the nanocrystalline phase(s) of glass ceramics is of interest for photoluminescence (PL) applications to control the energy transfer (ET) processes between dopants on the nanometer length scale. Here, the focus is on explaining the essential knowledge of the distribution of two groups of active ions: transition metal (Ni2+ and Cr3+) and rare earth (Yb3+ and Er3+) ions, which are doped into i) single‐phase Ga2O3 and ii) dual‐phase Ga2O3 and YF3 nanocrystals (NCs). These NCs are obtained by thermally crystallizing ternary silicate‐ and quinary fluorosilicate‐based glasses, respectively. It is found that the two types of active ions can successfully be doped into Ga2O3 NCs, resulting in enhanced ET between the dopants because of the small separation distance of, e.g., <10 Å, whereas ET is significantly suppressed when Ga2O3 and YF3 NCs are coprecipitated. In this case, the studied rare earth ions have a high propensity for being selectively doped in YF3 NCs. The studied transition‐metal ions can always be found in Ga2O3 NCs irrespective of the presence of the fluoride phase. The selective doping and the ET between the two types of active ions can be controlled simultaneously on annealing. This may allow for the achievement of diverse PL properties, such as ultrabroadband near‐infrared and upconversion‐mediated Stokes emissions.

The partitioning of rare earth ions (REs: Yb3+, Er3+, Eu3+ and Nd3+) in γ-Ga2O3 nanocrystals (NCs) precipitated in a nanostructured silicate glass ceramic is revealed, and the enrichment of REs in the NCs (bulk doping) rather than on the interfaces between the NCs and the surrounding glassy phase (surface doping) is differentiated.

Defects present ubiquitously in glasses exert a strong influence on the optical qualities and performances of glass, a phenomenon that has not been well studied to date.

An ultrabroadband near-infrared (NIR) emission of Ni 2+ is demonstrated in a highly transparent nano-glass ceramic (nano-GC) containing Ga 2 O 3 nanocrystals with 808 nm excitation of Nd 3+. It is also shown that by adding Yb 3+ as an energy transfer (ET) bridge, the Ni 2+ emission could be substantially enhanced. The dopant distribution was studied using advanced analytical transmission electron microscopy. This, together with optical transmission measurements, steady-state and time-resolved emission spectra, is utilized to understand the underlying ET mechanisms between Nd 3+ , Yb 3+ , and Ni 2+. The feasibility of this device as a viable source is demonstrated using dual-laser pumping at 808 and 980 nm for the greatest Ni 2+ emission enhancement reported to date. The Nd 3+ /Yb 3+ /Ni 2+ triply doped nano-GC offers a promising gain medium for broadband and tunable NIR fiber amplifiers.

Ni2+/Yb3+/Er3+/Tm3+ codoped transparent glass‐ceramics (GCs) containing both hexagonal β‐YF3 and spinel‐like γ‐Ga2O3 dual‐phase nanoparticles (NCs) are synthesized by melt‐quenching and subsequent heating procedures. Two techniques of transmission electron microscopy (TEM) nanoanalytics and optical spectroscopy are conjugated to understand the distribution of the rare‐earth ions (REs) and transition metals (TMs) in the nanostructured GCs. It is found that the REs are located predominantly in β‐YF3, whereas the TMs in γ‐Ga2O3 NCs. As a result, energy transfer (ET) between the REs and TMs is considerably suppressed due to the large spatial separation (> 3 nm), but it is enhanced between the REs partitioned in the β‐YF3 NCs. This has important implications for intended and demanding photoluminescence functions. For example, an ultrabroadband near‐infrared (NIR) emission in the wavelength region of 1000‐2000 nm covering the entire telecommunications window is observed for the first time. Meanwhile, intense upconversion (UC) emissions covering the 3 primary colors and locating in the first biological window can be also recorded under excitation by a single pump source at 980 nm.

research to applied industrial and social applications including but certainly not limited to window glasses, windscreens, kitchen cooktops, microscope and telescope lens, and optics, and so on, owing to such unmatched and outstanding properties as ease of large-scale and complex shape production as well as chemical and mechanical durability. [1] However, glasses, usually made by the traditional melt-quenching method viz., cooling a viscous liquid fast enough to avoid crystallization (known as supercooling), [2] are seriously constrained to those that entail an acceptable degree of glass-forming ability unless otherwise being made under extremely harsh conditions (e.g., superfast cooling or high-energy irradiation, etc.) that are not readily available to ordinary glass-making labs and factories. [3] This leads to a significantly limited range of available constituents and functions of the obtained glasses. For example, spectroscopic features of active dopants (e.g., rare-earth (REs) ions, transition, and main group metals) are closely associated with their chemical states and the surrounding chemical environments provided by the glass host; hence, it is possible to induce new photoluminescence (PL) functions such as ultrabroadband and enhanced up-/down-conversion emissions via proper doping, post thermal, and magnetic treatments or A new method is reported to achieve the manufacture of glass of arbitrary ratio of SiO 2 /P 2 O 5 which cannot be made by conventional melt-quenching method. The new method is termed "melt-in-melt" which encapsulates the key step in the glass manufacturing process, i.e. one molten glass is poured into another molten glass with a stirring at high temperatures. Because of near unlimited possibilities in designing new glass compositions, there is a correspondingly great degree of freedom in the topological engineering of the glass structure, which in turn strongly influences the photoluminescence (PL) properties of active dopants. As a proof concept, bismuth and erbium are selected as the indicator dopants for emphasizing the real advantages of the new method as an effective means to tailoring the PL properties of the doped glasses. The micro structure and element distribution within the fabricated glasses are comprehensively characterized by high-resolution scanning electron microscopy, micro-Raman and high-performance X-ray fluorescence spectroscopy. Phase separation occurring at both nano-and meso-scale is observed. Apart from the developed glasses being themselves promising broadband emission phosphors, the new glass-making method may extend the possible applications of glass for important photonic applications (e.g. optical sensing, lighting, display, optical amplification and lasing etc.).