The pure-phase Ba3-xCaxSi6O12N2:Eu2+ green phosphor: synthesis, photoluminescence and thermal properties

The promising green oxynitride phosphor, Ba3-xCaxSi6O12N2:Eu2+, was synthesized at 1350 degrees C for 5 hours under a reducing N-2/H-2 (5%) atmosphere via the solid-state reaction method. The XRD patterns confirm the formation of the pure phase of Ba3-xCaxSi6O12N2:Eu2+. With an increase in x, the emission spectra shift from 525 nm to 536 nm under near-UV (n-UV) excitation. Accordingly, we propose the underlying mechanisms for the red-shift of the emission spectra by adjusting the cation composition in the host. The influence of the size mismatch on the thermal quenching is also observed. The as-prepared green phosphor exhibits great thermal quenching property, with the remaining 83% of the initial emission intensity measured at 150 degrees C. The quantum efficiency is measured to be 35.2%. All the results indicate that the Ba3-xCaxSi6O12N2:Eu2+ can be a good candidate phosphor applicable to n-UV light-emitting diodes for solid-state lighting.