Spectroscopic properties of Sm ~(3+) ions in lead fluorophosphate glasses

摘要

The Sm ~(3+)-doped lead fluorophosphate glasses of composition 44P _2O _5-17K _2O-9Al _2O _3-(24-x)PbF _2-6Na _2O-xSm _2O _3, 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 Sm ~(3+) ions in lead fluorophosphate glasses. The decay rates for the ~4G _(5/2) level of Sm ~(3+) ions have been measured and are found to be single exponential at lower concentration (≤0.1 mol Sm _2O _3) and turn into non-exponential at higher concentrations (≥0.5 mol Sm _2O _3) due to energy transfer through cross-relaxation. The experimental lifetimes for ~4G _(5/2) level of Sm ~(3+) ions are found to decrease from 2.54 to 0.92 ms when the concentration increased from 0.01 to 2.0 mol Sm _2O _3 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.