Efficient red phosphor double-perovskite Ca3WO6 with A-site substitution of Eu3+.

Luminescent properties of Eu(3+) activated double perovskite structure Ca3WO6 were investigated. It emits an ideal red color centered at the wavelength of 618 nm with suitable excitation from f-f transitions of Eu(3+) ions (360-550 nm) matching the near ultraviolet and blue LEDs. Charge compensation effect of Li(+), Na(+), and K(+) was investigated, and K(+) proved to be the best. The co-doping ion K(+) has a great effect on the lattice distortion of the host matrix Ca3WO6, which facilitates the red emission of Eu(3+). The substitution site for Ca in Ca3WO6 was analyzed in detail by Raman spectra and calculation results. A-site substitution is responsible for the red emission of Eu(3+) activated Ca3WO6. The integrated emission intensity of optimal Ca3WO6:K(+),Eu(3+) excited at 395 nm is about 3.5 times greater than that of Y2O2S:Eu(3+) commercial phosphors, which makes it a promising red phosphor for white LEDs.