Preparation and fluorescence properties of novel alkaline earth silicate phosphors by reduction treatment of Eu3+ to Eu2+

The synthesis and emission spectrum control of novel Eu2+-activated amorphous alkaline earth silicate phosphors from the reduction of Eu3+-activated amorphous alkaline earth silicate phosphors is reported. The as-prepared Eu3+-activated amorphous alkaline earth silicate phosphors emitted red. Reduction using Ni-metal powder in a H2 (5%)/Ar (95%) atmosphere produced Eu2+-activated amorphous barium silicate phosphor that emitted green. Eu2+-activated amorphous calcium silicate was produced by reduction with ammonium chloride in air and emitted purple-blue. It was possible to control the emission spectrum by changing the reduction time. These results suggest the possibility to use three-band type phosphors for the fabrication of white light emitting diodes using one host crystal.