Preparation of Sr2CeO4:Eu3+,Dy3+ white luminescence phosphor particles and thin films by using an emulsion liquid membrane system

Sr2CeO4 and Sr2CeO4:Eu3+,Dy3+ phosphor particles and thin films were prepared by using an emulsion liquid membrane (ELM, water-in-oil-in-water (W/O/W) emulsion) system, containing VA-10 (2-methyl-2-ethylheptanoic acid) as extractant (cation carrier). A two-step extraction enabled efficient extraction for Sr3+ and rare earth ions, and the resulting precursor metal oxalate particles produced in the internal water phase of the ELM system were about 60 nm in diameter. Calcination of the oxalate particles in air gave submicrometer-sized Sr2CeO4 and Sr2CeO4:EU3+,Dy3+ particles, which showed blue and white luminescence, respectively, by UV excitation. Blue and white luminescence phosphor thin films were also prepared by soaking alumina substrates into the W/O emulsion containing precursor oxalate particles, followed by calcination in air.