Judd–Ofelt analysis of Pr3+ ions in Sr1.5Ca0.5SiO4 and Sr0.5Ca0.5TiO3 host matrices

Abstract The spectroscopic properties of Pr 3+ doped Sr 1 . 5 Ca 0.5 SiO 4 and Sr 0.5 Ca 0.5 TiO 3 host matrices have been investigated using optical absorption and emission spectra. The oscillator strengths of observed bands of Pr 3+ ions and Judd–Ofelt intensity parameters were calculated by including and excluding the hypersensitive 3 H 4  →  3 P 2 transition using standard and modified Judd–Ofelt (JO) theory. In both the host matrices the JO parameters follow the same trend as Ω 6  >  Ω 2  >  Ω 4 . The JO intensity parameters obtained by using the Modified JO theory was used to compute the radiative properties such as radiative transition probability ( A R ), branching ratio ( β R ) and radiative lifetime ( τ R ) for the observed fluorescence bands. The photoluminescence spectrum of Pr 3+ doped Sr 1.5 Ca 0.5 SiO 4 upon 444 nm excitation shows three emission peaks at 489, 608 and 733 nm corresponding to the transitions 3 P 0  →  3 H 4 , 3 H 6 and 3 F 4 respectively. But in the case of Sr 0.5 Ca 0.5 TiO 3 host matrix we observed an emission peak at 611 nm corresponding to the 1 D 2  →  3 H 4 transition at λ ex  = 336 nm. The experimental branching ratio ( β exp ) obtained from the fluorescence spectra was compared with the calculated values. The non radiative relaxation rate was calculated from the experimental ( τ exp ) and predicted ( τ R ) lifetimes. Stimulated emission cross section ( σ e ), gain bandwidth ( σ e × Δ λ eff ) and optical gain ( σ e  ×  τ R ) for 0.5 wt% Pr 3+ doped Sr 1.5 Ca 0.5 SiO 4 and Sr 0.5 Ca 0.5 TiO 3 phosphor samples were also calculated and their high value suggests its candidature as a good optical material.