Synthesis and luminescence properties of La2Zr2O7:R (R = Sm3+, Bi3+, Sm3+/Bi3+) phosphor

La 2 Zr 2 O 7 :R (R = Sm 3+ , Bi 3+ , Sm 3+ /Bi 3+ ) phosphors are synthesized by solid-state reaction method in air. Blue emission band peaking at ∼462 nm of La 2 Zr 2 O 7 :Bi 3+ phosphor with excitation at 312 nm is observed in the range of 370–610 nm due to 3 P 1 → 1 S 0 transition of Bi 3+ ion and D → 1 S 0 transition between Bi 3+ and Zr 4+ ions. La 2 Zr 2 O 7 :Sm 3+ phosphor with excitation at 407 nm shows reddish orange light in the range of 550–750 nm owing to 4 G 5/2 → 6 H J ( J  = 5/2, 7/2, 9/2, and 11/2) transitions of Sm 3+ ion. Tunable emission from blue to white of La 2 Zr 2 O 7 :Sm 3+ , Bi 3+ phosphor with excitation at 312 nm can be observed due to the changing Bi 3+ or Sm 3+ ion concentration . La 2 Zr 2 O 7 :Sm 3+ , Bi 3+ phosphor with excitation at 407 nm only emits reddish orange because Bi 3+ has no absorption at 407 nm. The energy transfer from Bi 3+ to Sm 3+ is discussed. The luminous mechanism is explained by the energy level diagrams of Bi 3+ and Sm 3+ ions.