Effect of modifying PbO on optophysical properties of Nd³⁺ -doped zinc phosphate glass

Full text: The effect of the modifying PbO on optical and physical properties of the zinc-phosphate glasses containing neodymium ions is investigated. Glasses having compositions (79-x)P₂O₅-20ZnO-xPbO-1Nd₂O₃ where x=0, 5, 10 and 20mol% are prepared by conventional melt-quenching method. X-ray diffractometry is used to confirm the amorphous nature of the glass samples. UV-Vis-IR absorption spectroscopy and photoluminescence spectroscopy techniques are used to study the effect of lead oxide on optical properties of the proposed glassy system. The introduction of PbO increases the refractive index and density of the glasses up to 1.48 and 3.545 gr.cm^-3, respectively. The addition of the lead oxide decreases direct and indirect band gaps which is consistent with formation of the non-bridging oxygens in the glass matrix due to the modification of the phosphate network by modifier. Judd-Ofelt analysis show that the optical quality factor of the Nd³⁺ ions increases by addition of PbO while the calculated lifetime of the ⁴G_7/2 drastically decreases from 228 to 95 for 0 and 20mol% of lead content, respectively. Five emission bands centered at 482, 527, 579, 600 and 660 nm are observed at visible range by exciting the glasses under 800 nm. The reduction in the radiative lifetime is obtained while the up-converted luminescence intensities quench. Improved physical properties, wide range of transparency and increased branching ratio of the 600 nm line may nominate the proposed phosphate glasses as candidates to develop solid state lasers. (author)