الملخص
Abstract : Tellurite glasses with composition 80TeO2 –10Nb2O5 – 10ZnO (TNbZ) in mol% codoped with x(Tm2O3/Dy2O3), where x= 0, 10000, 20000 and 30000ppm were prepared by using melt-quenching technique. The thermal and optical properties of these glasses were evaluated by differential scanning calorimetric (DSC) and UV-Vis-NIR spectroscopy, respectively. The thermal analysis revealed that the Tm3+/Dy3+ modified TNbZ host glass whicg possess high thermal stability and anti-crystallization process. Various parameters such as density and oxygen packing density, molar volume and oxygen molar volume, molar refraction, metallization criterion, molar polarizability, linear refractive index (n), third-order non-linear susceptibility and two photon absorption coefficient were calculated. By detailed investigations, it was observed that the linear refractive index significantly enhanced with reduction in the optical energy gap by increasing the concentrations of Tm3+/Dy3+ions. Raman scattering and calculated Raman gain spectral analysis for the fabricated glasses were also studied and it was researched that with the addition of Tm3+/Dy3+ ions to TNbZ glasses, the Raman intensity was increased due to distortion of TeO4, Te-O-Te chains andvi TeO3units. The evaluated Raman gain coefficient of such glasses was found to be about 33–80 times compared to fused-silica (0.89 ×10-13 m/W) at 440 cm-1. The observed results revealed that the fabricated glasses modified with Tm3+/Dy3+ are promising materials which can efficiently be used for specific optical applications such as Raman gain amplifier. The glass with the composition of 20V2O5- 75CdO- 5Ag2O (in mol %) have also been prepared by a melting technique. The photoconductivity (σph) at light intensities and temperatures were measured. The thermal stability and structural properties of the fabricated glasses were investigated by several techniques such as Raman-scattering spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetric (DSC). The detailed analysis revealed that the fabricated glass possess thermal stability of ∆T= 97 0C and anti-crystallization parameter of S= 5.5. The value of σph and dark conductivity, , were 40.2 × 10-4 and 36.8 × 10-4 Ω-1∙ cm-1 at 300 K, respectively. The observed value of the prepared glass was larger as compared to other glass reported in the literature. Thus, it is believed that such glasses are promising future which could be used for the fabrication of various high efficient optoelectronic devices. The structures of the fabricated glasses were investigated by Raman-scattering spectroscopy.
