Emission improvement and tunable emission properties of SrZrSi2O7:R (R = Sm3+ and Sm3+/Bi3+) phosphors

Abstract

A series of SrZrSi2O7:R (R = Sm3+, Bi3+, Bi3+/Sm3+) phosphors are synthesized successfully in air via high temperature solid-state reaction method. The crystal structure, lifetime, energy transfer (ET) process, and luminescence properties of samples are investigated in detail. Host SrZrSi2O7 with excitation at 300 nm ultraviolet (UV) light emits blue light due to the Zr4+ - O2− transition inside [ZrO6] group. SrZrSi2O7:Bi3+ phosphor with excitation at 315 nm UV light emits blue light owing to the 3P0,1 → 1S0 transitions of Bi3+ ion. SrZrSi2O7:Sm3+ and SrZrSi2O7:Sm3+, Bi3+ phosphors with excitation at 300 nm UV light show a tunable emission due to ET process from [ZrO6] to Sm3+ and from Bi3+ to Sm3+, respectively, and they only emit red-orange light under excitation 407 nm because of the 4G5/2 → 6H5/2, 6H7/2, 6H9/2, and 6H11/2 transitions of Sm3+ ion. The optimal concentrations of Sm3+ and Bi3+ ions are ~6 and 4 mol%, respectively. The lifetime of SrZrSi2O7:Sm3+ phosphor decreases from 1.127 ms to 0.897 ms with increasing Sm3+ concentration in the range of 2–12 mol%, and that of SrZrSi2O7:6%Sm3+, Bi3+ phosphor decreases from 1.005 ms to 0.948 ms with increasing Bi3+ concentration in the range of 1–8 mol%. The luminous mechanisms of samples are explained by the energy level diagram. The experimental results are helpful for the luminescence improvement and emission adjustion of other Sm3+-doped phosphors.