Synthesis and luminous characteristics of Ba2MgSi2−xAlxO7: 0.1Eu2+, 0.1Mn2+ phosphor for WLED

The shift of the emission band to longer wavelength (yellow-orange) of the Ba2MgSi2−xAlxO7: 0.1Eu2+ phosphor under the 350–450 nm excitation range has been achieved by adding the codoping element (Mn2+) in the host. The single-host silicate phosphor for WLED, Ba2MgSi2−xAlxO7: 0.1Eu2+, 0.1Mn2+ was prepared by high-temperature solid-state reaction. It was found experimentally that, its three-color emission peaks are situated at 623, 501 and 438 nm, respectively, under excitation of 350–450 nm irradiation. The emission peaks at 438 and 501 nm originate from the transition 5d to 4f of Eu2+ ions that occupy the two Ba2+ sites in the crystal of Ba2MgSi2−x AlxO7, while the 623 nm emission is attributed to the energy transfer from Eu2+ ions to Mn2+ ions. The white light can be obtained by mixing the three emission colors of blue (438 nm), green (501 nm) and red (623 nm) in the single host. When the concentrations of the Al3+, Eu2+ and Mn2+ ions were 0.4, 0.1 and 0.1 mol, respectively, the sample presented intense white emission. The addition of Al ion to the host leads to a substantial change of intensity ratio between blue and green emissions. White light could be obtained by combining this phosphor with 405 nm light-emitting diodes. The near-ultraviolet GaN-based Ba2MgSi1.7 Al0.3O7: 0.1Eu2+, 0.1Mn2+ LED achieves good color rendering of over 85.