Photoluminescence properties and crystal structure of color-tunable yellow–orange–carroty–red emissive Sr2(1−x)NaxP2O7:xSm3+ phosphors for near-UV/blue light-based white LEDs
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A series of Sr2(1−x)NaxP2O7:xSm3+ phosphors with adjustable emission have been synthesized via one-step calcination process of the precursors prepared by co-precipitation method successfully. The crystal structure and luminescent properties of the phosphors were analyzed in detail. Because the Sm3+ could occupy two different types of Sites (Sr1 and Sr2), the emission spectra of the Sr2−xP2O7:xSm3+ phosphors excited at 402 nm showed an emission band consisting of two symmetrical single bands (Em1 and Em2) in the wavelength range of 580–620 nm with a peak at 599 nm (4G5/2 → 6H7/2). The optimal doping concentration of these phosphors was at x = 0.04. The charge compensator Na+ ions can not only improve emission luminous intensity and quantum efficiency (QE) of the Sr2P2O7:Sm3+, but also change the shape and position of the emission peak at 599 nm. The color tunable wide gamut light can be controlled through properly adjusting the excitation wavelength of obtained samples, covering the yellow, orange, carroty and red chromaticity region, indicating Sr2(1−x)NaxP2O7:xSm3+ phosphors have high absorptions from the near ultraviolet to blue region and can be efficiently excited by commercial NUV and blue LEDs, thus can be used for developing warm white LEDs.
Commission International de I′Eclairage
This work was supported by the Natural Science Foundation of China (51702033) and the Program of Chongqing Municipal Education Commission (KJ1501126).