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

Abstract

La2Zr2O7:R (R = Sm3+, Bi3+, Sm3+/Bi3+) phosphors are synthesized by solid-state reaction method in air. Blue emission band peaking at ∼462 nm of La2Zr2O7:Bi3+ phosphor with excitation at 312 nm is observed in the range of 370–610 nm due to 3P1 → 1S0 transition of Bi3+ ion and D → 1S0 transition between Bi3+ and Zr4+ ions. La2Zr2O7:Sm3+ phosphor with excitation at 407 nm shows reddish orange light in the range of 550–750 nm owing to 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2, and 11/2) transitions of Sm3+ ion. Tunable emission from blue to white of La2Zr2O7:Sm3+, Bi3+ phosphor with excitation at 312 nm can be observed due to the changing Bi3+ or Sm3+ ion concentration. La2Zr2O7:Sm3+, Bi3+ phosphor with excitation at 407 nm only emits reddish orange because Bi3+ has no absorption at 407 nm. The energy transfer from Bi3+ to Sm3+ is discussed. The luminous mechanism is explained by the energy level diagrams of Bi3+ and Sm3+ ions.