Combustion synthesis and luminescent properties of a new material Li2(Ba0.99,Eu0.01)SiO4:B3+ for ultraviolet light emitting diodes

Using urea as fuel and boric as flux, a novel bluish green emitting phosphor Li2(Ba0.99,Eu0.01)SiO4:B3+ has been successfully synthesized using a combustion method. The material has potential application as the fluorescent material for ultraviolet light-emitting diodes (UV-LEDs). The dependence of the properties of Li2(Ba0.99,Eu0.01)SiO4:B3+ phosphors upon urea concentration, boric acid doping and initiating combustion temperature were investigated. The crystallization and particle sizes of Li2(Ba0.99,Eu0.01)SiO4:B3+ have been investigated by using powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Luminescence measurements showed that the phosphors can be efficiently excited by ultraviolet (UV) to visible region, emitting a bluish green light with peak wavelength of 490 nm. The results showed that the boric acid was effective in improving the luminescence intensity of Li2(Ba0.99,Eu0.01)SiO4 and the optimum molar ratio of boric acid to barium nitrate was about 0.06. The optimized phosphors Li2(Ba0.99,Eu0.01)SiO4:B0.063+ showed 160% improved emission intensity compared with that of the Li2(Ba0.99,Eu0.01)SiO4 phosphors under UV (λex=350 nm) excitation.