Effect of P5 +/Al3 + molar ratio on structure and spectroscopic properties of Nd3 +/Al3 +/P5 + co-doped silica glass

• Silica glasses doped with P5 +, Nd3 + and Al3 + were successfully prepared.
• Their optical and spectroscopic properties were measured at room temperature.
• Structure–property relationships of these glasses were investigated.

Glasses with compositions of (95.8-x) SiO2–4Al2O3–xP2O5–0.2Nd2O3 (in mol%, x = 0–10) were prepared. Structural variation caused by P5 + was investigated by Judd–Ofelt parameters and Raman spectra. Results reveal that Nd3 + preferentially coordinates to PO sites at molar ratio of P5 +/Al3 + > 1 and thus it leads to a sudden change in fluorescence effective linewidth, stimulated emission cross section, fluorescence lifetime and non-radiative transition rate of Nd3 + ions. The fluorescence lifetime changes in the range of 315–379 μs. The emission cross section changes in the range of 1.39–1.79 × 10− 20 cm2. With the increase of P5 +/Al3 + ratio, the fluorescence effective linewidth varies from 45.77 to 37.03 nm. The shortest fluorescence lifetime was observed at molar ratio of P5 +/Al3 + = 1. The maximum non-radiative transition rate of 1694/s occurred at molar ratio of P5 +/Al3 + = 1.25. The highest emission cross section of 1.79 × 10− 20 cm2 was obtained at the highest P5 +/Al3 + molar ratio. Furthermore, structure–property relationship in these glasses was discussed through Judd–Ofelt parameters and luminescent behaviors.