Pressure-Stimulated Synthesis and Luminescence Properties of Microcrystalline (Lu,Y)₃Al₅O₁₂:Ce³⁺ Garnet Phosphors

Abstract

The Lu2.98Ce0.01Y0.01Al5O12 and Y2.99Ce0.01Al5O12 phosphors were synthesized by solid state reaction at temperature 1623 K and pressure 1.5 × 10(7) Pa in (95% N2 + 5% H2) atmosphere. Under the conditions, the compounds crystallize in the form of isolated euhedral partly faceted microcrystals ∼19 μm in size. The crystal structures of the Lu2.98Ce0.01Y0.01Al5O12 and Y2.99Ce0.01Al5O12 garnets have been obtained by Rietveld analysis. The photoluminescence (PL) and X-ray excited luminescence (XL) spectra obtained at room temperature indicate broad asymmetric bands with maxima near 519 and 540 nm for Y2.99Ce0.01Al5O12 and Lu2.98Ce0.01Y0.01Al5O12, respectively. The light source was fabricated using the powder Lu2.98Ce0.01Y0.01Al5O12 phosphor and commercial blue-emitting n-UV LED chips (λ(ex) = 450 nm). It is found that the CIE chromaticity coordinates are (x = 0.388, y = 0.563) with the warm white light emission correlated color temperature (CCT) of 6400 K and good luminous efficiency of 110 lm/W.

Structure evolution and photoluminescence of Lu3(Al,Mg)2(Al,Si)3O12:Ce3+ phosphors: new yellow-color converters for blue LED-driven solid state lighting

“…Besides, it's also entering into several new application fields, 2 including backlights for liquid-crystal displays and portable electronics, automobile headlights, medical and architecture lighting, and plant cultivation, etc. 3,4 Initially, YAG:Ce was proposed for use in displays in 1967, 5 and later, it was quickly employed for white light generation when the bright blue InGaN diode was invented. The blue light from LED is absorbed by the Ce 3+ ions of YAG:Ce via the allowed 4f→5d transiƟon that generates the excited state, which then gives a wide-band yellow emission band through the inverse 5d→4f transition.…”

“…First, the garnet structure is, at present, the only known oxide host wherein the Ce 3+ dopant can be excited by blue light and emit in the green-orange spectral region with high quantum efficiency and high thermal stability. 1b); for example, (Y,Lu) 3 Al 5 O 12 :Ce shows the green to greenish-yellow emission shift with increasing Y/Lu ratio; 4,23 (2) replacing Al-Al in tetrahedral/octahedral coordination with equal-valence cation pair such as Mg(Ca)-Si (Fig. Second, LuAG:Ce emits a green color, which makes it much easier to achieve yellow emission via red-shift.…”

Chromaticity-Tunable and Thermal Stable Phosphor-in-Glass Inorganic Color Converter for High Power Warm w-LEDs

“…Corresponding to the parity allowed Ce 3+ : 4 f -5 d transitions, the PL spectra present a broadband emission, while the PLE spectra show a wide excitation band as well [16,17,18]. Due to a larger crystal field splitting of the Ce 3+ 5 d levels in the silicate garnet, the emission spectrum of this phosphor was redshifted compared to the commercially available phosphor YAG:Ce 3+ .…”

The Preparation and Optical Properties of Novel LiLa(MoO4)2:Sm3+,Eu3+ Red Phosphor

“…Hence this color cannot meet indoor light requirements which require warm white light and an excellent CRI [5]. In addition, the blue chip InGaN and yellow phosphor possess a different failure rate and in the case of long working hours this may cause chromatic aberration and reduced white performance [6,7,8,9,10]. To solve this problem, researchers have developed red, green and blue emission phosphors using near ultraviolet (NUV: 350~410 nm) excitation [11,12].…”