Nickel ion doped transparent bulk glass-ceramics containing K 2 SiF 6 , ZnF 2 , and KZnF 3 nanocrystals were elaborated to show the prospect that this novel group of oxyfluoride glass-ceramics is promising for transition metal ion based photonics. These new oxyfluoride glass-ceramics exhibit a new broadband luminescence of Ni 2+ ions in the intriguing near-IR spectral region ranging from 1200 to 2400 nm. Ni 2+ ions are incorporated into the precipitated K 2 SiF 6 , ZnF 2 , and KZnF 3 crystals, which provide octahedral sites for Ni 2+ and make it optically active. Taking into account the microstructure of phase separation observed by replica TEM, a detailed mechanism of phaseseparation-assisted nanocrystallization was described for these oxyfluoride glasses. These results allow one to establish a full physical model of the nanocrystallization mechanism. For the precipitation of fluoride crystallites, not only can the nanometric size be explained but also the formation of different crystal phases can be controlled by the initial amorphous phase separation of droplet or interpenetrating structure with a sufficiently elaborated glass design.

Transparent KF-ZnF(2)-SiO(2) glass-ceramics were prepared with the precipitation of KZnF(3)Ni(2+) nanocrystals. During excitation with a wavelength of 405 nm at room temperature, a broadband near-IR emission centered at 1695 nm with the FWHM of more than 350 nm was observed, which is originated from the T(2g)3(F3)→A(2g)3(F3) transition of octahedral Ni(2+) incorporated in the KZnF(3) crystalline phase. In comparison to oxide glass-ceramics, a redshift of the luminescence is observed, which is due to the low crystal field of these octahedral Ni(2+). The shift and extension of near-IR emission in the KZnF(3):Ni(2+) nanocrystals embedded in a glassy matrix do not only complete the broadband emission in the whole near-IR region for the Ni(2+) ions-based photonics, but also open an easy way to approach the broadband optical amplifier and tunable lasers operating in the wavelength region near 1800 nm, which was up to now achieved by codoping of several types of active ions.

Series of glassy and glass‐ceramic samples in the GeSe2–Ga2Se3–NaI system is prepared by melt‐quenching technique and the glass‐forming region is well‐defined by XRD investigations. Na‐ion conduction behavior is systemically studied by impedance measurements. For the glasses in the series (100−2x)GeSe2–xGa2Se3–xNaI, ionic conductivities increased with increasing x, whereas the attributed activation energy of ion conduction decreases. The enhanced mechanism is discussed by employing Raman spectra. In addition, the effect of the crystal phases NaI and Ga2Se3 on the ionic conduction behavior in the (70−x)GeSe2–xGa2Se3–30NaI samples is discussed. Although it shows that the poorly conducting crystallites of NaI and Ga2Se3 have a negative effect on the ionic conductivities in this series, the highest ionic conductivity of 1.65 × 10−6 S/cm is obtained in the 45GeSe2–25Ga2Se3–30NaI glass. Finally, this study also demonstrates a possible way to search appropriate Na‐ion solid electrolytes for all‐solid‐state batteries.

Through a careful composition design, new oxyfluoride glass‐ceramics (GCs) containing BaLiF3 nanocrystals with sizes of around 30 nm were prepared. Microstructural characterizations show interpenetrating phase separation in the sample with a composition of 15BaF2–15ZnF2–70SiO2, after thermal treatment at 580°C for 40 h which leads to the nanocrystallization of BaLiF3. The BaLiF3 nanocrystals embedded in the glassy matrix could provide Ba or Li sites for the incorporation of optically active rare earth and transition‐metal ions, which provides a possibility to explore novel photonic properties by the codoping of rare earth and transition‐metal ions in GC materials.

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