Glass‐forming range and electrical conduction properties of V2O5–P2O5–WO3 ternary system were investigated. The glass‐forming ability of this system was quite good within a wide compositional area where the P2O5 content ranges from 20 to 80 mol%. This glass exhibited a high dc‐conductivity up to 6.71 × 10−4Ω/cm at 473 K. The variation of conductivity (log(σT)) of the glass with temperature (1/T) exhibited a linear relationship, which suggests electrical conduction through the small polaron hopping above room temperature. Compositional effect on the conductivity was studied upon varying WO3 and P2O5 concentration. Substitution of V2O5 with P2O5 resulted in a decrease of the conductivity with the increase of activation energy, while substitution of WO3 showed relatively little effect on the activation energy. Structural modification along with the valence state change of vanadium and tungsten ions were discussed in connection with Raman spectroscopy and X‐ray photoelectron spectroscopy analysis.

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We observed experimentally that the formation of β‐PbF2 nanocrystals (NC) in oxyfluoride glass conspicuously altered the local structures of rare‐earth (RE) ions, which then enabled their intra4f‐configurational transitions to be luminuous even at mid‐infrared (MIR) wavelengths. Radiative emission centered at ∼2.87 μm originating from Dy3+:6H13/2→6H15/2 transition was remarkably enhanced after the NC were formed by thermal treatment in an ambient atmosphere. However, emission intensities due to Er3+:4I11/2→4I13/2 and Ho3+:5I6→5I7 transitions turned out to be less dependent on the NC formation, which indicated that the enhancement of MIR emission depended on RE.