Influence of Ho2O3 on Optimizing Nanostructured Ln2Te6O15 Anti‐Glass Phases to Attain Transparent TeO2‐Based Glass‐Ceramics for Mid‐IR Photonic Applications

The transparent TeO2‐based glass‐ceramics (GCs) have yet to achieve the breakthrough in photonic technologies, because of poor understanding in optimizing the growth of nanostructured crystalline phases. In the present investigation, the size effect of phase‐separation‐induced, nanostructured Ln2Te6O15‐based (Ln: Gd, Ho) “anti‐glass” phase in Ho2O3‐modified TeO2‐based TTLG (in mol%, 80TeO210TiO25La2O35Gd2O3) glass has considered to achieve transparent GCs. Raman study of TTLG glass reveals the presence of TeO3, TeO3 + 1, and TeO4 units with average TeO coordination number as 3.49. The formation of nanostructured Ln2Te6O15 phases in GCs is confirmed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. Furthermore, TEM analysis confirms that an increase of Ho2O3 concentration has reduced the size of phase‐separated domains in nanoscale with superstructure formation to attain transparent GCs. The superiority of this obtained transparent GCs as photonic material for near‐IR (NIR) to mid‐IR (MIR) range has been established by the realization of enhanced luminescence intensities and bandwidth at ≈2900 nm (Ho3+: 5I6 → 5I7) and ≈2050 nm (Ho3+: 5I7 → 5I8). This study offers an opportunity to fabricate the various accessible lanthanide ions‐doped and/or co‐doped TTLG glass with control over nanostructure, to design a series of GCs which are transparent from visible to MIR range.