LaGaO3:A (A = Sm3+ and/or Tb3+) as promising phosphors for field emission displays

Abstract

LaGaO₃:Sm³⁺, LaGaO₃:Tb³⁺ and LaGaO₃:Sm³⁺,Tb³⁺ phosphors were prepared through a Pechini-type sol–gel process. X-Ray diffraction, field emission scanning electron microscopy, photoluminescence (PL), and cathodoluminescence (CL) spectroscopy were utilized to characterize the synthesized phosphors. Under excitation with ultraviolet light (250–254 nm), the LaGaO₃:Sm³⁺, LaGaO₃:Tb³⁺ and LaGaO₃:Sm³⁺,Tb³⁺ phosphors mainly show the characteristic broadband emission (from 300 to 600 nm with a maximum around 430 nm) of the LaGaO₃host lattice, accompanied by the weak emission of Sm³⁺ (⁴G_5/2 → ⁶H_5/2, ⁶H_7/2, ⁶H_9/2 transitions) and/or Tb³⁺ (⁵D_3,4 → ⁷F_6,5,4,3 transitions). However, under excitation by low-voltage electron beams (1–3 kV), the LaGaO₃:Sm³⁺, LaGaO₃:Tb³⁺ and LaGaO₃:Sm³⁺,Tb³⁺ phosphors exhibit exclusively the characteristic emissions of Sm³⁺ and/or Tb³⁺ with yellow (Sm³⁺), blue (Tb³⁺, with low concentrations) and white (Sm³⁺ + Tb³⁺) colors, respectively. The CL intensities (brightness) of the LaGaO₃:Sm³⁺ and LaGaO₃:Tb³⁺ phosphors are higher than those of the commercial products (Zn, Cd)S:Ag⁺ (yellow) and Y₂SiO₅:Ce³⁺ (blue), respectively. Related luminescence mechanisms are proposed to explain the observed phenomena.