Tuning of the Emission Color of Ba 1− x Ga 2 S 4 : x Eu 2 + Phosphors for Use in Three‐Band White LEDs

Ba 1‐ x Ga 2 S 4 : x Eu 2 + ( x = 0.10, 0.25, 0.50, 0.75, 1.0) phosphors were prepared by performing a solid‐state reaction. The PL spectra of the Ba 1− x Ga 2 S 4 : x Eu 2 + phosphors were recorded. Very broad excitation bands are located in the range 300–480 nm, which suggests that the Ba 1− x Ga 2 S 4 : xEu 2 + can be used as color emission phosphors when pumped with an excitation of 465 nm, which is the wavelength of a commercial blue‐emitting diode. The emission wavelength at the maximum PL intensity (λ max ) for the Ba 1− x Ga 2 S 4 : x Eu 2 + phosphors increases gradually from 504 to 548 nm as the mole fraction of europium ions ( x ) in the phosphors increases. The variation in λ max for the Ba 1− x Ga 2 S 4 : x Eu 2 + phosphors with the mole fraction of europium ions can be interpreted in terms of the crystal structures of the Ba 1− x Ga 2 S 4 : x Eu 2 + phosphors. A three‐band white emission was obtained by coating a mixture of Ba 0. 5 Ga 2 S 4 :0. 5Eu 2 + and CaS :Eu 2+ phosphors onto the surface of a blue‐emitting diode.