Synthesis Process of BaMgAl[sub 10]O[sub 17]:Eu[sup 2+] from Sol-Gel-Derived Eu[sup 2+]-Activated Fluoride Precursors without H[sub 2] Annealing Treatments

Barium magnesium aluminate, BaMgAl 10 O 17 , was synthesized by a solid-state reaction between Al 2 O 3 and sol-gel-derived BaMgF 4 precursors. The reaction temperature necessary for producing a single-phase material was reduced to 1300°C because of the higher reactivity and lower melting point of the fluoride precursors. Eu-doped BaMgF 4 was also prepared and characterized to examine its suitability as a precursor for synthesizing BaMgAl 10 O 17 : Eu 2 + blue phosphors. It was demonstrated that Eu 3 + , which was used in the acetate form as a starting material, was reduced to Eu 2 + in the sol-gel processing of BaMgF 4 , as indicated by a broad blue emission due to an allowed d-f transition at 420 nm with an ultraviolet excitation at 290 nm. BaMgAl 10 O 17 : Eu 2 + , which showed efficient blue emissions at 450 nm with an ultraviolet excitation at 254 nm, was successfully prepared by heating a mixture of Al 2 O 3 and Eu-doped BaMgF 4 at 1300°C without any special reducing treatment.