Preparation and photoluminescence properties of γ-KCaPO4: Eu2+ phosphors for near UV-based white LEDs

Novel whitish-blue phosphors based on a phosphate host matrix, γ-KCaPO4: Eu2+, were prepared by a conventional solid-state reaction method using slightly phosphorus deficient conditions and their photoluminescence properties were investigated. The concentration quenching process, temperature dependence of the luminescence and decay curve were also investigated. The γ-KCaPO4: Eu2+ phosphor was efficiently excited by UV–Visible light at wavelengths of 200–450 nm and exhibited a bright whitish-blue emission with a maximum peak wavelength of 473 nm. All of these characteristics suggest that the γ-KCaPO4: Eu2+ phosphors combined with red phosphors could be applicable to near UV-based white LEDs, i.e., only two kinds of phosphor powders are needed for the formation of white light.

► The successful preparation of a new noble γ-KCaPO4: Eu2+ whitish-blue phosphor.
► Photoluminescent properties, concentration quenching effect, decay time and thermal luminescent properties were investigated.
► Broad excitation band in the NUV area.
► Intense broad whitish-blue emission band.
► Stokes shift and critical distance for energy transfer between the Eu2+ ions were calculated.