Synthesis and competitive luminescence quenching mechanism of Ca₃Al₂O₆:Ln³⁺ (Ln: Dy and Sm) phosphors

Sm³⁺ and Dy³⁺ activated Ca₃Al₂O₆ phosphors were produced through a gel combustion method using Urea + β-Alanine, Urea, and Urea + Glycine as fuels. The crystal structure and the phase purity of the obtained materials were characterized by X-ray powder diffraction (XRD). Ca₃Al₂O₆:Sm³⁺ phosphor shows characteristic emission lines (565 nm, 602 nm, 649 nm, and 714 nm) in the orange red region assigned to ⁴G_5/2→⁶H_J (J = 5/2, 7/2, 9/2, 11/2) transitions of Sm³⁺. The strongest peak is located at 602 nm. Emission spectra of Ca₃Al₂O₆:Dy³⁺ show that there are two dominant peaks centered at 480 nm and 573 nm emitting blue and yellow light. Optimum doping concentrations of Sm(NO₃)₃ and Dy(NO₃)₃ are 0.01 % and 0.03 %, respectively. The concentration quenching mechanism is verified to be a dipole-dipole interaction as the type of energy transfer among Sm³⁺-Sm³⁺ and Dy³⁺-Dy³⁺ ions. The critical distance is also calculated to be 24.19 Å and 16.77 Å, respectively.