Solid-State Combinatorial Screening of (Sr,Ca,Ba,Mg)2Si5N8:Eu2+ Phosphors

Lee, Bong-Hyun; Lee, Sang-Jun; Jeong, Hyung Gon; Sohn, Kee‐Sun

doi:10.1021/co100046u

Cited by 51 publications

(28 citation statements)

References 25 publications

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“…Moreover, since these materials have been synthesized under ambient pressure they have a lower production cost than high-pressure synthesized nitridosilicates materials such as M 2 Si 5 N 8 :Eu (M = Ca, Sr, Ba), MAlSiN 3 :Eu (M = Ca, Sr)5678910. Among oxonitridosilicate phosphors, there is an increasing interest in layered MSi 2 O 2 N 2 :Eu (M = Ca, Sr, Ba) which show efficient yellow, green and cyan emission, respectively11121314151617.…”

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confidence: 99%

Structural phase transitions and photoluminescence properties of oxonitridosilicate phosphors under high hydrostatic pressure

Lazarowska

Mahlik

Liu

2016

Sci Rep

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Spectroscopic properties of a series of (Sr0.98-xBaxEu0.02)Si2O2N2 (0 ≤ x ≤ 0.98) compounds has been studied under high hydrostatic pressure applied in a diamond anvil cell up to 200 kbar. At ambient pressure the crystal structures of (Sr0.98-xBaxEu0.02)Si2O2N2 (0 ≤ x ≤ 0.98) are related to the ratio of strontium to barium and three different phases exists: orthorhombic Pbcn(0.78 ≤ x ≤ 0.98), triclinic P1 (0 < x ≤ 0.65) and triclinic P1 (0.65 < x < 0.78). It was found that Eu2+ luminescence reveals abrupt changes under pressure (decay time, energy and shape) which indicate the variation of the local symmetry and crystal field strength in Eu2+ sites. These changes are attributed to the reversible pressure-induced structural phase transitions of triclinic (Sr0.98-xBaxEu0.02)Si2O2N2 into orthorhombic structure. Pressure in which phase transition occurs decreases linearly with increasing of Ba composition in (Sr0.98-xBaxEu0.02)Si2O2N2 series. Additionally, very different pressure shifts of the Eu2+ luminescence in different phases of (Sr0.98-xBaxEu0.02)Si2O2N2:Eu from −40 cm−1/kbar to 0 cm−1/kbar have been observed. This effect is explained by different interaction of the Eu2+ 5d electron with the second coordination sphere around the impurity cations.

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confidence: 99%

Structural phase transitions and photoluminescence properties of oxonitridosilicate phosphors under high hydrostatic pressure

Lazarowska

Mahlik

Liu

2016

Sci Rep

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“…2 that all the excitation and emission spectra of the MSi 2 O 2 N 2 :Eu 2+ 0.05 (M = Sr, Mg, Y) compounds are similar in their excitation patterns and in their emission domain wavelengths of 535 nm as well; these similarities also suggest that the crystal structure is not very much influenced by the composition of M (M = Sr, Mg, Y) but seems to be fixed by the SrSi 2 O 2 N 2 network [9]. Despite the alien ele- and (Sr,Ca,Ba,Mg) 2 Si 5 N 8 : Eu 2+ phosphors, for which a conspicuous spectral shift took place due to the incorporation of alien alkali earth elements [21][22][23]. The effect of Y inclusion should be minimal because the doping content of Y was negligibly small.…”

Section: Resultsmentioning

confidence: 80%

Luminescence properties of (Sr0.95−x−yMgxYy)Si2O2−yN2+y:Eu2+ 0.05 for novel LED conversion phosphors

2011

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2+0.05 (M = Sr, Mg, Y) compounds were synthesized by ahigh-temperature solid-state reactionand were characterized using X-ray power diffraction as well as excitation and emission spectroscopy. As compared to the pure SrSi 2 O 2 N 2 :Eu 2+ 0.05 , the emission intensity of the new MSi 2 O 2 N 2 :Eu 2+ 0.05 (M = Sr, Mg, Y) compound was increased by 65 %. Meanwhile, it was also possible to improve the ratio of thermal quenching up to 88 % by substituting the Sr with Mg and/or Y in the SrSi 2 O 2 N 2 :Eu 2+ 0.05 crystal structure. This improvement was mainly due to the intrinsic electronic negativity and size effect of Y 3+ , which leads to the shrinkage of the O/N ratioand the relaxation of local strain around the Eu 2+ ion in the (Sr 0.95-x-y Mg x Y y )Si 2 O 2-y N 2+y :Eu 2+ 0.05 structure.Consequently, the (Sr 0.68 Mg 0.27 )Si 2 O 2 N 2 :Eu 2+ 0.05 phosphor is expected to be useful as a novel conversion phosphor with high thermal stability for white-light LEDs.

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“…8 Nitridosilicates such as M2Si5N8:Eu 2+ (M = Ca, Sr, Ba) are an excellent class of orange-red phosphors, showing high efficiency and high color purity under near-UV to blue light excitation, and thermal stability up to 200 °C. [9][10][11][12][13][14][15] Moisture-induced degradation of Sr2Si5N8:Eu 2+ phosphors has been minimised by adding a hydrophobic nanolayer formed by hydrolysis and polymerization of tetraethylorthosilicate and polydimethylsiloxane. 16 Another approach was to add a passivating SrSiO3 layer through thermally treatment in a N2-H2 atmosphere.…”

Section: ■ Introductionmentioning

confidence: 99%

Enhanced Photoluminescence Emission and Thermal Stability from Introduced Cation Disorder in Phosphors

et al. 2017

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Optimizing properties of phosphors for use in white-light-emitting diodes (WLEDs) is an important materials challenge. Most phosphors have a low level of lattice disorder due to mismatch between the host and activator cations. Here we show that deliberate introduction of high levels of cation disorder leads to significant improvements in quantum efficiency, stability to thermal quenching, and emission lifetime in Sr(CaBa)SiN:Eu (x = 0-1.5) phosphors. Replacing Sr by a (CaBa) mixture with the same average radius increases cation size variance, resulting in photoluminescence emission increases of 20-26% for the x = 1.5 sample relative to the x = 0 parent across the 25-200 °C range that spans WLED working temperatures. Cation disorder suppresses nonradiative processes through disruption of lattice vibrations and creates deep traps that release electrons to compensate for thermal quenching. Introduction of high levels of cation disorder may thus be a very useful general approach for improving the efficiency of luminescent materials.

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Solid-State Combinatorial Screening of (Sr,Ca,Ba,Mg)₂Si₅N₈:Eu²⁺ Phosphors

Cited by 51 publications

References 25 publications

Structural phase transitions and photoluminescence properties of oxonitridosilicate phosphors under high hydrostatic pressure

Structural phase transitions and photoluminescence properties of oxonitridosilicate phosphors under high hydrostatic pressure

Luminescence properties of (Sr0.95−x−yMgxYy)Si2O2−yN2+y:Eu2+ 0.05 for novel LED conversion phosphors

Enhanced Photoluminescence Emission and Thermal Stability from Introduced Cation Disorder in Phosphors

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