Ca(Mg_0.8Al_0.2)(Si_1.8Al_0.2)O₆:Ce³⁺,Tb³⁺ Phosphors: Structure Control, Density-Functional Theory Calculation, and Luminescence Property for pc-wLED Application

Abstract

A modified structure Ca­(Mg0.8Al0.2)­(Si1.8Al0.2)­O6 (denoted as CMASO) from the evolution of CaMgSi2O6 (denoted as CMSO) codoped with Ce3+ and Tb3+ ions was designed successfully by solid reaction method for application in phosphor-converted white-light-emitting diode (pc-wLED). The Rietveld refinement of these two structures verified the changes derived from the replacement of some of the Mg2+ and Si4+ ions by Al3+ ions. The band gaps were calculated by density-functional theory (DFT) calculation method to verify the change of Al3+ ions replacing further, and the diffuse reflectance spectra (DRS) proved the veracity of the calculation result. The phosphors CMASO:Ce3+ showed blue emission excited by a wider excitation wavelength from 280 nm to 370 nm. The change of structure lead to the absorbable range broaden and the emission peak shifted to longer wavelength, compared with CMSO:Ce3+, although the amount of emitting center was the same. The reason for these phenomena was discussed in detail. The codoped phosphors CMASO:Ce3+,Tb3+ exhibited different emission colors from blue to green as the concentration of Tb3+ ions increased. Combined with commercial red phosphor CaAlSiN3:Eu2+ and ultraviolet LED (UV-LED) chips, the selected appropriate samples achieved white emission. The correlated color temperature (CCT) was 6137 K and the color rendering index (Ra) was 80.5, indicating that they could act as potential phosphors for possible applications in pc-wLED.

Thermally Stable Tb3+/Eu3+-Codoped K0.3Bi0.7F2.4 Nanoparticles with Multicolor Luminescence for White-Light-Emitting Diodes

“…Currently, the doping of two diverse rare-earth ions into a single-phased host via using their energy transfer (ET) processes is regarded as an efficient approach to achieve multicolor-tunable phosphors. − In comparison, the Eu 3+ ion is usually considered as a red-emitting activator owing to its bright red emissions arising from 5 D 0 → 7 F J ( J = 2, 3, and 4) transitions, while the Tb 3+ ion is a promising green-emitting activator on account of its special emissions from the 5 D 4 → 7 F J ( J = 3, 4, 5, and 6) transitions. − Besides, it has been proved that the Tb 3+ ions can transfer energy to Eu 3+ ions, leading to the realization of multicolor emissions in Tb 3+ /Eu 3+ -codoped phosphors, such as Ca 5 (BO 3 ) 3 F/Tb 3+ /Eu 3+ , LaPO 4 /Tb 3+ /Eu 3+ , Ba 2 HfF 8 /Tb 3+ /Eu 3+ , KBaGd­(WO 4 ) 3 /Tb 3+ /Eu 3+ , and so forth. − Thus, it is very necessary for us to investigate the luminescent behaviors of Tb 3+ /Eu 3+ -codoped phosphors as well as explore their potential applications. Notably, the luminescent efficiency of rare-earth ions is sharply dependent on the hosts, and these compounds with low phonon energies are known as excellent hosts since they are able to block the possibility of non-radiative (NR) transition. , Currently, bismuth-based inorganic compounds, which contain the fluoride element, are deemed to be promising candidates for rare-earth ions as host materials, which is not only because of the attractive virtues of Bi 3+ ions, such as low cost and non-toxicity, but also due to the substitution of Bi 3+ ions by rare-earth ions, which does not induce any charge imbalances. , As a consequence, an array of bismuth-containing fluorides, such as BiF 3 , NaBiF 4 , K 0.3 Bi 0.7 F 2.4 , and so forth, were developed for rare-earth ions. − Nevertheless, the majority of these research studies mainly focused on their upconversion performance, whereas the investigation on their photoluminescence properties as well as their feasibility for white-LED applications was not efficient.…”

VUV–UV–vis Luminescence, Energy Transfer Dynamics, and Potential Applications of Ce3+- and Eu2+-Doped CaMgSi2O6

“…Alkaline earth silicate CaMgSi 2 O 6 is a suitable host compound for luminescence of lanthanide and transition metal ions because of high chemical stability and luminescence efficiency. − In this paper, based on the systematical investigations on the vacuum ultraviolet–ultraviolet–visible (VUV–UV–vis) spectra of Ce 3+ - and Eu 2+ -doped CaMgSi 2 O 6 at cryogenic temperatures, the luminescence concentration-/thermal-quenching behaviors of Ce 3+ and Eu 2+ ions and the Ce 3+ → Eu 2+ energy transfer dynamics are discussed in detail. The possible applications of codoped samples in optical thermometry and anticounterfeiting are demonstrated.…”

Effect of the Concentration of SrAl2O4: Eu2+and Dy3+ (SAO) on Characteristics and Properties of Environment-Friendly Long-Persistent Luminescence Composites from Polylactic Acid and SAO

“…Ethoxy is a special group that can be hydrolyzed in water or solvent to form silanol, and it is also a group contained in KH550. The -OH group of PLA can react with silanol, which in turn makes a stable covalent bond formed on the surface of the PLA polymer [13,14] (Schemes 1 and 2). The treated SAO was vacuum filtered in a drying box at 80 °C for 6 hours.…”