A green-yellow emitting β-Sr2SiO4:Eu2+ phosphor for near ultraviolet chip white-light-emitting diode

Sr2SiO4:xEu2+ phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4:xEu2+ phosphor manipulated by Eu2+ concentration was studied. The phase transited from β to α' in Sr2SiO4:xEu2+ phosphor with increasing europium concentration. The single β phase was formed as x ≤ 0.005 and changed α' phase when x > 0.01. The emission spectrum of the β-Sr2SiO4:Eu2+ phosphor consisted of a green-yellow broadband peaking at around 540 nm and a blue band at 470 nm under near ultraviolet excitation. The white LEDs by combining near ultraviolet chips with β-Sr2SiO4:Eu2+ phosphors were fabricated. The luminous efficiency (15.7 lm/W) was higher than α'-Sr2SiO4:Eu2+ phosphor white LED.