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Fluoride glass is considered as an excellent optical material owing to its ultralow phonon energy (578 cm−1). However, its high thermal expansion coefficient (15.87 × 10−6/K) and deformability severely limit applications under service environments with high temperature, high humidity, and high‐power irradiation. To overcome these limitations, we developed a ZBLAN‐based fluoride glass ceramics (CZBLAN GCs) contained the negative thermal expansion material‐CaZrF6 crystals by phase‐separation engineering. The ability to control the precipitation of the desired crystal phase was achieved by adequate compositional design for phase separation, yielding improved or new properties in the development of fluoride GCs. With the successful precipitation of very uniformly dispersed single CaZrF6 crystals in the glass phase (up to ∼40% crystallinity), a significantly lower thermal expansion coefficient (3.66 × 10−6/K) in the fluoride system was achieved. Moreover, enhanced fluorescence properties of Eu‐doped CZBLAN GCs were observed compared with those of Eu‐doped ZBLAN glass owing to the lower phonon energy in GCs. [ABSTRACT FROM AUTHOR]

For transparent low melting inorganic glass, which is relevant for sealing and additional applications, Pb‐containing glasses have reached the lowest melting point and best comprehensive performance. Considering potential toxicity and regulatory limitations, there is urgent need to develop Pb‐free ultra‐low melting point glass. Herein, we systemically investigated the structure and luminescence evolution of the Pb‐free ultra‐low melting quaternary tin fluorophosphate glasses (NaF‐SnF2‐SnO‐P2O5), in which varied NaF content was tuned to affect the properties of glass. With NaF content increases, the Sn‐O and P‐O bonds have been gradually transformed to Sn‐F and P‐F bonds, and the phosphrous tetrahedron PO4 has been converted to PO3F. The weaken bonding results in the decrease of the ultra‐low melting point to 329°C when NaF increased to 15 a.t.%, 29oC lower than the ternary glass. The blue shifts of both absorption and photoluminescence spectra were observed due to the higher ionic character of glass structure with NaF increases. As reported previously in the ternary tin fluorophosphate glass, the quaternary glass system also shows a phosphorescence behavior (∼1 s) due to the existence of oxygen vacancies. Additionally, the changes in oxygen vacancy defects correlate with the NaF content, thus affecting the decay time as well. The ultra‐low melting point luminescent quaternary tin fluorophosphate glasses (NaF‐SnF2‐SnO‐P2O5) may be relevant for opto‐electronic applications such as the packaging in displays or light‐emitting diodes. [ABSTRACT FROM AUTHOR]

Fluoindinate glass (FIG) is considered an ideal material for fiber laser devices and mid‐infrared bulk optics components owing to its ultra‐low phonon energy and broad transparency window. However, the heat generated by devices fabricated with FIG during their operation limits its application. Therefore, there is an urgent need to study its high‐temperature properties. In this study, the thermal properties, microstructure, crystal phase behaviors, and optical and luminescent properties of high‐temperature FIG were comprehensively evaluated. We also attempted to reveal the changes in its structure at high temperatures using variable‐temperature Raman spectroscopy. We first found that the stretching vibration intensity of nonbridging F(Fnb) decreases, and the bending vibration of FIG increases with an increase in temperature, indicating that high temperatures could lead to the fracture of bridge bonds between some [InF6]3− octahedrons. Certainly, this will lead to glass structural instability, which will further increase the tendency of FIG to undergo devitrification in high‐temperature conditions. We believe that this work will provide a reference for the performance improvement and application of fluoride glass at high temperatures. [ABSTRACT FROM AUTHOR]

Transparent glass-ceramics containing Er3+:CaF2 crystallites were prepared with the co-firing method. The formation process of the glass-ceramics was investigated by means of SEM, XRD, and DSC. The results reveal that the Er3+:CaF2 nanocrystals do not dissolve into the fluorophosphates ( FP) glassmelt until the co-firing temperature increase higher than about 920°C. Below this temperature, Er3+:CaF2 survives the co-firing process and the nanocrystals just grow to spherical crystals of micrometers in size. Co-firing temperature higher than this temperature leads to the dissolution of Er3+:CaF2 and the dissolved Er3+:CaF2 recrystallized during quenching process and takes the shape of dendrite. [ABSTRACT FROM AUTHOR]

For transparent low melting inorganic glass, which is relevant for sealing and additional applications, Pb‐containing glasses have reached the lowest melting point and best comprehensive performance. Considering potential toxicity and regulatory limitations, there is urgent need to develop Pb‐free ultra‐low melting point glass. Herein, we systemically investigated the structure and luminescence evolution of the Pb‐free ultra‐low melting quaternary tin fluorophosphate glasses (NaF‐SnF2‐SnO‐P2O5), in which varied NaF content was tuned to affect the properties of glass. With NaF content increases, the Sn‐O and P‐O bonds have been gradually transformed to Sn‐F and P‐F bonds, and the phosphrous tetrahedron PO4 has been converted to PO3F. The weaken bonding results in the decrease of the ultra‐low melting point to 329°C when NaF increased to 15 a.t.%, 29oC lower than the ternary glass. The blue shifts of both absorption and photoluminescence spectra were observed due to the higher ionic character of glass structure with NaF increases. As reported previously in the ternary tin fluorophosphate glass, the quaternary glass system also shows a phosphorescence behavior (∼1 s) due to the existence of oxygen vacancies. Additionally, the changes in oxygen vacancy defects correlate with the NaF content, thus affecting the decay time as well. The ultra‐low melting point luminescent quaternary tin fluorophosphate glasses (NaF‐SnF2‐SnO‐P2O5) may be relevant for opto‐electronic applications such as the packaging in displays or light‐emitting diodes. [ABSTRACT FROM AUTHOR]