Wide-band blue-emitting in Ce3+ doped Ca2YZr2Al3O12 garnet-type phosphor designed via local structural lattice distortion and synthesized in nonreducing atmosphere

Abstract

It is of great significance to explore blue photoluminescent phosphor for white light-emitting diodes excited by near-ultraviolet chip. However, it is very challenging to prepare efficient blue luminescence in phosphor by an unsophisticated synthesis process. In this work, a series of blue-emitting Ca 2 Y 1-x Zr 2 Al 3 O 12 : xCe 3+ phosphors are designed via local lattice distortion and synthesized in nonreducing atmosphere. The crystal structure of samples and the coordination environment of Ce 3+ have been investigated in detail by X-ray diffraction and Rietveld refinement method. The wide-band blue emission peaking at 460 nm is attributed to a relaxed crystal field strength. Based on dodecahedron distortion caused by unequal increase of Ce–O bond length, the wavelength of blue color luminescence tuning can be realized from 459 nm to 472 nm. In addition to the concentration quenching effect, the fluorescent lifetimes, thermal quenching effect, the internal quantum efficiency, CIE chromaticity coordinates and related mechanisms of samples have also been studied systematically. Using the representative sample with other tricolor phosphors on a 365 nm chip, a prototype LED device with chromaticity point of (0.394, 0.384) and high CRI (93.5) at CCT of 3755 K is fabricated. All the results suggest that Ca 2 Y 1-x Zr 2 Al 3 O 12 : xCe 3+ phosphors can be conducted as potential alternative of blue-emitting phosphor for near-ultraviolet pumped white light-emitting diodes.