Tunable‐spectrum Mn²⁺ doped garnet transparent ceramics for high‐color rendering laser lighting

Abstract

Laser diodes (LDs) packaged with transparent ceramics show the low thermal expansion coefficient and high thermal conductivity, but there is a problem of the low color render index (CRI) owing to the lack of red component in current transparent ceramics. Mn 2+ doped garnet transparent ceramics with adjustable color from yellow to red have been prepared via a solid-state reaction-vacuum sintering process, which have a high transmittance of 78.6% at 800 nm. Two main emission peaks of this ceramic are monitored at 590 and 749 nm, and the gratifying luminous performance improvement is obtained due to the charge compensation effect, electron cloud expansion effect, and efficient energy transfer. LD system fabricated with the obtained ceramics and blue LD shows a high-CRI of 80, low correlated color temperature of 4098 K, and good luminous efficiency of 96.91 m/W.

White Light Emission and Energy Transfer in CaHf4(PO4)6: Ce3+, Dy3+

“…Meanwhile, a non-radiative energy transfer process takes place from 5d excited states of Ce 3+ to 4 D 7/2 of Dy 3+ ions, and then a non-radiative transition to the 4 F 9/2 energy level occurs. As a result, the characteristic emission bands of Dy 3+ originating from 4 F 9/2 to 6 H 15/2 (blue), 6 H 13/2 (yellow), and 6 H 11/2 (red) are observed.…”

“…However, due to the lack of red components, the color rendering index (CRI) of the existing commercial WLEDs is low (CRI < 80), and their correlated color temperature (CCT) is high (CCT > 5000 K). [4][5][6][7][8] Researchers have tried to add the red luminescence center to YAG: Ce 3+ to reinforce the red emission, but the result is not very satisfactory. [9][10][11] An alternative way is to apply additional red phosphors, but multiple phosphors not only led to resorption problems but also made the coating procedure more challenging.…”

Spectrum regulation of YAG:Ce/YAG:Cr/YAG:Pr phosphor ceramics with barcode structure prepared by tape casting

“…Gd 3+ also has been added to YAG:Ce by replacing a certain amount of Y 3+ to improve the color rendering of white light in many works 32–34 . The Mg 2+ –Si 4+ pairs and Mn 2+ ions can also effectively compensate for the orange–red and red spectrum components in YAG:Ce ceramics and yield high‐quality warm white light 35–37 . Nevertheless, the energy transfer between ions and the reduced thermal conductivity makes the LE of phosphor ceramics unsatisfactory.…”

“…[32][33][34] The Mg 2+ -Si 4+ pairs and Mn 2+ ions can also effectively compensate for the orange-red and red spectrum components in YAG:Ce ceramics and yield highquality warm white light. [35][36][37] Nevertheless, the energy transfer between ions and the reduced thermal conductivity makes the LE of phosphor ceramics unsatisfactory. To improve the color rendering of white LEDs, composite ceramics with novel structures were also designed such as YAG:Ce/YAG:Ce,Cr dual-layered ceramics 38 and YAG:Ce/(Gd,Y)AG:Ce dual-layered composite ceramics.…”

Preparation of YAG nanopowders and ceramics via coprecipitation: Effects of treatment modes of precipitates

“…Yttrium aluminum garnet (Y 3 Al 5 O 12 , YAG) has been widely known as an important transparent material for window, fluorescent, and solid-state laser application due to its excellent optical properties. [1][2][3][4][5][6][7] Compared with YAG single crystals, polycrystalline YAG ceramics can realize large sizes, desired shapes, multifunctional composite structures, high-concentration and homogeneous ion doping, short production cycles, and low costs under the premise of ensuring satisfactory mechanical, chemical, and optical properties, [8][9][10][11][12] thus, attracting increasing attention. Obtaining a high-quality powder with nanoscale size, good dispersity and narrow size distribution is a key precondition for the preparation of high-performance YAG transparent ceramics.…”