Incorporation of Si4+–N3− into Ce3+ -Doped Garnets for Warm White LED Phosphors

Setlur, Anant; Heward, William J.; Hannah, M. E.; Happek, U.

doi:10.1021/cm801732d

Cited by 235 publications

(181 citation statements)

References 26 publications

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“…12,13 However, despite many advantages, the final phosphor product suffers from complexities associated with the combination of several phosphors used in the fabrication and its significant degradation during heating, which reduce the lifetime and efficiency of WLEDs. 10,11,14 The pursuit in this direction has led to identify new class of phosphors having broadband near white emitting properties based on oxides, [15][16][17][18] oxyfluorides, 19,20 nitrides, 21,22 oxynitrides, [23][24][25] sulfides 26,27 and halides. 28,29 Among all, the oxyfluoride (for example: Sr 2.975-x -Ba x Ce 0.025 AlO 4 F) phosphors have been seen with alacrity as the most efficient matrix for photoluminescence due to their low phonon energy.…”

Section: Introductionmentioning

confidence: 99%

KCa4(BO3)3:Ln3+ (Ln = Dy, Eu, Tb) phosphors for near UV excited white–light–emitting diodes

et al. 2013

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A series of doped KCa 4 (BO 3 ) 3 :Ln 3+ (Ln: Dy, Eu and Tb) compositions were synthesized by solid-state reaction method and their photoluminescent properties were systematically investigated to ascertain their suitability for application in white light emitting diodes. The X-ray diffraction (XRD) and nuclear magnetic resonance (MAS-NMR) data indicates that Ln 3+ -ions are successfully occupied the noncentrosymmetric Ca 2+ sites, in the orthorhombic crystalline phase of KCa 4 (BO 3 ) 3 having space group Ama2, without affecting the boron chemical environment. The present phosphor systems could be efficiently excitable at the broad UV wavelength region, from 250 to 350 nm, compatible to the most commonly available UV light-emitting diode (LED) chips. Photoluminescence studies revealed optimal near white-light emission for KCa 4 (BO 3 ) 3 with 5 wt.% Dy 3+ doping, while warm white-light (CIE; X = 0.353, Y = 0.369) is obtained at 1wt.% Dy 3+ ion concentration. The principle of energy transfer between Eu 3+ and Tb 3+ also demonstrates the potential white-light from KCa 4 (BO 3 ) 3 :Eu 3+ ,Tb 3+ phosphor. Whereas, single Tb 3+ and Eu 3+ -doped systems showed bright green (Tb 3+ ) and red (Eu 3+ ) emissions, respectively. Having structural flexibility along with remarkable chemical/thermal stability and suitable quantum efficiency these phosphors can be promising candidates as white-light-emitter for near UV LEDs.

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Section: Introductionmentioning

confidence: 99%

KCa4(BO3)3:Ln3+ (Ln = Dy, Eu, Tb) phosphors for near UV excited white–light–emitting diodes

et al. 2013

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“…[25][26][27][28][29][30] It means that the interaction between luminescent ions is strong at this inter-ionic distance. In the CeAl 11 [31][32][33][34][35][36][37][38][39][40] Like BAM: Eu 2+ blue-emitting phosphor, aluminates phosphors suffer from serious deterioration of luminescence efficiency during continuous excitation in fluorescent lamps. 41 Wang et al have successfully proposed a new method of Si-N doping in BAM: Eu 2+ phosphor to improve its luminescence intensity and thermal stability.…”

Section: Resultsmentioning

confidence: 99%

“…An expanded electron cloud is intuitively shown due to higher formal charge of N 3− compared with O 2− and more covalent nature of the metal-nitrogen chemical bonding versus metal-oxygen. 25 Si-N doping should play a role in shifting the UV luminescence spectra of normal Ce 3+ ions to longer wavelength theoretically. As seen in Figure 9, a small redshift of UV emission peak is truly observed due to stronger crystal-field splitting of the 5d levels of Ce 3+ and nephelauxetic effect caused by Si-N doping.…”

Section: Resultsmentioning

confidence: 99%

Tunable Luminescence of CeAl₁₁O₁₈Based Phosphors by Replacement of (AlO)⁺by (SiN)⁺and Co-Doping with Eu

Yin

Chen

Wang

et al. 2014

ECS J. Solid State Sci. Technol.

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A series of Si-N or Eu-Li doped CeAl 11 O 18 and CeAl 12 O 18 N phosphors are prepared by solid-state reaction. Their structure and luminescence are researched carefully. Si-N doping with the concentration less than 8% can be successfully dissolved into CeAl 11 O 18 crystal lattice and doesn't change the matrix structure, only resulting in crystal lattice shrinkage due to the shorter bond length for Si-N bond versus Al-O bond. It is observed that blue emission gradually decreases and UV emission becomes stronger due to the gradual disappearance of O Me ions with the increase of Si-N doping. 1-7 These phosphors show some features of high quantum yield, chemical and radiation stability, which make them still under research in many areas now. It is demonstrated here that some aluminates will show very interesting results by tuning the crystal structure slightly, despite (oxy)nitride based phosphors are researched widely and greatly developed recently due to their high quantum efficiency, excellent thermal, physical and chemical stabilities, and therefore show large potential to be implemented in highly efficient and reliable white LEDs. [8][9][10] Generally, the hexagonal aluminates are divided into three different groups:11-13 1. compounds MeAl 12 O 19 (Me = Ca, Sr, Eu) with magnetoplumbite-type structure; 2. compounds MeMgAl 10 O 17 (Me = Ba, Sr, Eu) with β-alumina structure; 3. distorted magnetoplumbitetype structure such as CeAl 11 O 18 . The β-alumina structures and magnetoplumbite are both composed of spinel blocks formed by the close packing of Al and O atoms. There is the merely significant difference in the two mirror planes (z = 0.25 and 0.75) between these two structures. In the β-alumina structure, each mirror plane contains one large cation and one oxygen. The non-close-packed mirror plane is connected with the stable spinel blocks closely. In the magnetoplumbite structure, the mirror planes contain one large cation and more oxygens 1. Generally, CeAl 11 O 18 is considered to have distorted magnetoplumbite structure. The difference from the normal magnetoplumbite-type structure is that La (Ce) large ions are considered to be partially replaced by O ions, O Me as an abbreviation.11 O Me is present because of non-ideal stoichiometry of CeAl 11 O 18 with respect to the ideal MeAl 12 O 19 composition for magnetoplumbite structure (large-cation/small-cation/anion = 1/12/19). Just due to this disorder, CeAl 11 O 18 exhibits special luminescence properties, which will be discussed later.Within those hexagonal aluminates, as a kind of self-activated phosphor, CeAl 11 O 18 shows very interesting characteristics, i.e. two emission peaks one UV band at ∼350 nm and one main blue band at ∼460 nm respectively. As we know, UV light can kill bacteria effectively and blue light is essential in photosynthesis for green plant. Due to its special luminescence properties, CeAl 11 O 18 based phosphors have been applied in sterilization, therapeutic, cosmetic skin treatment and promoting plant growth in greenhouse.14 To meet...

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“…Because the valence state of an activator ion depends on the coordination environment, the photoluminescent properties of phosphors can be controlled by modifying the covalency and polarizability of activator−ligand bonds in phosphors [11][12][13][14]. Moreover, the fluoride lattice provides a high coordination number for doped rare earth ions, and the high ionicity of the rare-earth-fluorine bond results in a wide band gap, low vibrational energies, and low probability of inter-configurational transitions [15].…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the fluoride lattice provides a high coordination number for doped rare earth ions, and the high ionicity of the rare-earth-fluorine bond results in a wide band gap, low vibrational energies, and low probability of inter-configurational transitions [15]. It has been previously reported that incorporating Si 4+ −N 3− into Ce 3+ -or Eu 2+ -doped phosphors will lead to a red shift in the 4f−5d emission owing to the lower electronegativity of N 3− compared to O 2− [11,12] Sample Characterization. The crystalline phases of each sample were identified by powder X-ray diffraction (XRD) measurements using a XD-3 diffractometer (PERSEE) with a Cu Kα radiation source (λ = 0.154 nm).…”

Section: Introductionmentioning

confidence: 99%

Enhanced luminescence properties of Sr3−xEuxAlO4−yNyF phosphors

Gao¹,

Meng²,

Zhang³

et al. 2015

Ceramics International

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Incorporation of Si⁴⁺–N³⁻ into Ce³⁺ -Doped Garnets for Warm White LED Phosphors

Cited by 235 publications

References 26 publications

KCa4(BO3)3:Ln3+ (Ln = Dy, Eu, Tb) phosphors for near UV excited white–light–emitting diodes

KCa4(BO3)3:Ln3+ (Ln = Dy, Eu, Tb) phosphors for near UV excited white–light–emitting diodes

Tunable Luminescence of CeAl₁₁O₁₈Based Phosphors by Replacement of (AlO)⁺by (SiN)⁺and Co-Doping with Eu

Enhanced luminescence properties of Sr3−xEuxAlO4−yNyF phosphors

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Incorporation of Si4+–N3− into Ce3+ -Doped Garnets for Warm White LED Phosphors

Cited by 235 publications

References 26 publications

KCa4(BO3)3:Ln3+ (Ln = Dy, Eu, Tb) phosphors for near UV excited white–light–emitting diodes

KCa4(BO3)3:Ln3+ (Ln = Dy, Eu, Tb) phosphors for near UV excited white–light–emitting diodes

Tunable Luminescence of CeAl11O18Based Phosphors by Replacement of (AlO)+by (SiN)+and Co-Doping with Eu

Enhanced luminescence properties of Sr3−xEuxAlO4−yNyF phosphors

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Resources

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Incorporation of Si⁴⁺–N³⁻ into Ce³⁺ -Doped Garnets for Warm White LED Phosphors

Tunable Luminescence of CeAl₁₁O₁₈Based Phosphors by Replacement of (AlO)⁺by (SiN)⁺and Co-Doping with Eu