Spectroscopic properties of Sm3+ ions in lead fluorophosphate glasses

The Sm3+-doped lead fluorophosphate glasses of composition 44P2O5–17K2O–9Al2O3–(24−x)PbF2–6Na2O–xSm2O3, where x=0.01, 0.05, 0.1, 0.5, 1.0 and 2.0 mol%, have been prepared by conventional melt quenching technique and are characterized through differential thermal analysis, Raman, absorption and emission spectra and decay rate measurements. Free-ion Hamiltonian model for energy level analysis and Judd–Ofelt theory for spectral intensities have been used to analyze the spectroscopic properties of Sm3+ ions in lead fluorophosphate glasses. The decay rates for the 4G5/2 level of Sm3+ ions have been measured and are found to be single exponential at lower concentration (≤0.1 mol% Sm2O3) and turn into non-exponential at higher concentrations (≥0.5 mol% Sm2O3) due to energy transfer through cross-relaxation. The experimental lifetimes for 4G5/2 level of Sm3+ ions are found to decrease from 2.54 to 0.92 ms when the concentration increased from 0.01 to 2.0 mol% Sm2O3 due to energy transfer. In order to know the nature of the energy transfer mechanism, the non-exponential decay rates are well fitted to Inokuti–Hirayama model for S=6, which indicates that the energy transfer process is of dipole–dipole type.