Optical Investigation of Sm³⁺ Doped Zinc-Lead-Phosphate Glass

Samarium doped lead-zinc-phosphate glasses having composition (60−x)P₂O₅-20PbO-20ZnO-xSm₂O₃ where x=0, 0.5, 1.0, 3.0mol% were prepared by using the melt quenching technique. The Archimedes method was used to measure their densities, which are used to calculate the molar volumes. The values of densities lie in the range 3.698–4.090 gm/cm³ whereas those of molar volume lie in the range of 37.24–40.00 cm⁻³. UV-vis-NIR absorption spectroscopy in the wavelength range 200–2000 nm was carried out. Absorption spectra consist of seven absorption peaks corresponding to the transitions from the ⁶H_5/2 ground state to various excited energy levels. The energy band gap measured from the optical absorbance is found to be in the range of 3.88-4.43 eV and 3.68-4.33 eV for direct and indirect transitions, respectively. In addition, the photoluminescence spectrum shows four prominent emission bands centered at 560, 597, 642 and 700 nm corresponding to the ⁴G_5/2−⁶H_J (J=5/2, 7/2, 9/2, 11/2) transitions respectively and the intensity of all the bands are enhanced as the concentration of Sm³⁺ ions increases.