Broadband photoluminescence in the (CaO-Al2O3-SiO2):Eu system

Phosphors of the (CaO-Al2O3-SiO2):Eu system obtained by direct solid-state synthesis in air at 1300°C produce broadband photoluminescence (PL) covering the entire visible range under excitation by a nitrogen laser. Upon vacuum annealing, the PL intensity in (CaO-Al2O3-SiO2):Eu and (CaO-Al2O3-2SiO2):Eu samples exhibits a several-fold increase and the latter phosphor yields blue emission according to the CIE color standard. The annealing of a (CaO-Al2O3):Eu composition leads to a change in the emission color from red (close to that according to the EBU scale) to blue (in the same scale). Vacuum-annealed (CaO-2Al2O3):Eu phosphor yields red emission (close to that according to the NTSC scale), while (2CaO-Al2O3):Eu composition exhibits intense purple luminescence.