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

A series of SrZrSi 2 O 7 :R (R = Sm 3+ , Bi 3+ , Bi 3+ /Sm 3+ ) 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 SrZrSi 2 O 7 with excitation at 300 nm ultraviolet (UV) light emits blue light due to the Zr 4+ - O 2− transition inside [ZrO 6 ] group. SrZrSi 2 O 7 :Bi 3+ phosphor with excitation at 315 nm UV light emits blue light owing to the 3 P 0,1  →  1 S 0 transitions of Bi 3+ ion. SrZrSi 2 O 7 :Sm 3+ and SrZrSi 2 O 7 :Sm 3+ , Bi 3+ phosphors with excitation at 300 nm UV light show a tunable emission due to ET process from [ZrO 6 ] to Sm 3+ and from Bi 3+ to Sm 3+ , respectively, and they only emit red-orange light under excitation 407 nm because of the 4 G 5/2  →  6 H 5/2 , 6 H 7/2 , 6 H 9/2 , and 6 H 11/2 transitions of Sm 3+ ion. The optimal concentrations of Sm 3+ and Bi 3+ ions are ~6 and 4 mol%, respectively. The lifetime of SrZrSi 2 O 7 :Sm 3+ phosphor decreases from 1.127 ms to 0.897 ms with increasing Sm 3+ concentration in the range of 2–12 mol%, and that of SrZrSi 2 O 7 :6%Sm 3+ , Bi 3+ phosphor decreases from 1.005 ms to 0.948 ms with increasing Bi 3+ 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 Sm 3+ -doped phosphors.