Synthesis and luminescent properties of (Ce_0.67-xGd_xTb_0.33) MgAl₁₁O₁₉ phosphors

Phosphors with (Ce_0.67-xGd_xTb_0.33) MgAl₁₁O₁₉ (0≤x≤0.37) composition were prepared by sol-gel processing. The preparation process, crystal structure and luminescent properties of the phosphor powders were investigated. The excitation spectrum is characteristic of Ce³⁺ ion, while the emission spectrum is composed of lines from Tb³⁺ ion with main emission peaks at around 542 nm and 487 nm. As the Gd³⁺ concentration increases, the luminescent intensity at about 542 nm increases to a maximum when x is about 0.12 and then decreases again at higher concentration of Gd³⁺ ion, whereas, the luminescence at about 487 nm follows the contrary rule.