Effects of Nd³⁺ Doping and Heat Treatment on Bismuth Niobium Tellurite Transparent Glass‐ceramics

Tellurite glass and anti‐glass samples of two systems: 12.5Bi 2 O 3 –12.5Nb 2 O 5 –(75‐x)TeO 2 –xNd 2 O 3 and 7.5Bi 2 O 3 –7.5Nb 2 O 5 –(85‐x)TeO 2 –xNd 2 O 3 ; x = 0 and 1 mol% are prepared by melt–quenching. Transparent glass‐ceramics (TGCs) containing anti‐glass inclusions co‐existing with the glass are prepared by heat–treatment 26 °C above their respective glass transition temperatures. Heating at a higher temperature of 510 °C formed opaque crystalline samples. The effects of Nd 3+ doping and heat treatment on the samples are studied by X–ray diffraction (XRD), density measurements, Differential scanning calorimetry (DSC), micro‐Raman, and UV–visible spectroscopy. The growth of inclusions of anti‐glass phases in the TGCs is confirmed by optical microscopy. XRD studies showed sharp peaks of orthorhombic BiNbTe 2 O 8 and TeO 2 phases in TGC samples. DSC studies found that the addition of Nd 3+ enhances the glass transition temperature. Micro‐Raman studies found very similar spectra in both anti‐glass inclusions and glass matrix confirming that the anti‐glass inclusions have vibrational disorder. The size of inclusions is found to be higher in Nd 3+ doped sample containing lower concentration of Bi 2 O 3 and Nb 2 O 5 (7.5 mol%). The Nd 3+ doped samples exhibit broad near‐infrared emission bands on excitation with 785 nm laser light.