Enhancement of PL intensity and formation of core-shell structure in annealed Ca 2-x/2 (Si 1-x P x )O 4 :Eu 2+  phosphor

Nakano, Hiromi; Yokoyama, Nobuyuki; Banno, Hiroki; Fukuda, Koichiro

doi:10.1016/j.materresbull.2016.07.002

Cited by 8 publications

(7 citation statements)

References 16 publications

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“…Here, the box in the chemical formula represents vacancies according to a previous paper [6]. The P-doped C 2 S:Eu 2+ phosphor with x = 0.06 exhibited the highest PL intensity among those with 0 ≤ x ≤ 0.20 [12]. …”

Section: Resultsmentioning

confidence: 99%

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The Effect of Heat Treatment on the Emission Color of P-Doped Ca2SiO4 Phosphor

et al. 2017

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In a series of (Ca2–x/2–yEuy□x/2)(Si1–xPx)O4 (x = 0.06, 0.02 ≤ y ≤0.5), various color-emitting phosphors were successfully synthesized by a solid-state reaction. These phosphors were characterized by photoluminescence (PL) spectroscopy, X-ray powder diffractometry, transmission electron microscopy, and X-ray absorption fine structure spectroscopy. We evaluated the effect of heat treatment on PL properties with various annealing temperatures at 1373–1773 K for 4 h before/after reduction treatment from Eu3+ to Eu2+. In the red-emitting (Ca1.95Eu3+0.02□0.03)(Si0.94P0.06)O4+δ phosphor, the highest PL intensity exhibited when it was annealed at 1773 K. On the other hand, in the green-emitting (Ca1.95Eu2+0.02□0.03)(Si0.94P0.06)O4 phosphor, the highest PL intensity was realized when it was annealed at 1473 K and consequently treated under a reductive atmosphere. With increasing annealing temperature, the emission peak wavelength steadily decreased. Furthermore, with increasing Eu2+ content, the emission peak wavelength increased, with the color of emitting light becoming yellowish. Thus, the PL properties of the phosphors were affected by both the structural change from β to α’L, which occurred by heat treatment, and the amount of doped Eu ions.

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Section: Resultsmentioning

confidence: 99%

“…Thus, the change of crystal structures by heat treatment must be potentially able to improve the photoluminescence (PL) properties of the phosphors. In fact, we have succeeded in the further improvement of the PL intensities by the annealing of the green-emitting P-doped C 2 S phosphor [12]. …”

Section: Introductionmentioning

confidence: 99%

The Effect of Heat Treatment on the Emission Color of P-Doped Ca2SiO4 Phosphor

et al. 2017

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“…Its disordered crystal structure (space group Pnma ) has been suggested to be made up of the two mirror-related structural configurations with P 2 1 / n 11 symmetry, the atom arrangements of which were very similar to that of the β-phase. The doped Ca 2 SiO 4 crystals have been reported as promising host materials for a light-emitting diode (LED) phosphors. − When the γ-, α′ L -, α′ H -, α-, and β-phases were activated with Eu 2+ ion, the emission spectra, induced by the 5d → 4f transition of Eu 2+ , have been dependent on the phase compositions . However, the photoluminescence (PL) properties of the IC-phase have, to the authors’ best knowledge, never been reported so far.…”

Section: Introductionmentioning

confidence: 99%

Crystal Structure and Photoluminescence Properties of an Incommensurate Phase in EuO- and P₂O₅-Doped Ca₂SiO₄

et al. 2019

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We have for the first time clarified the incommensurately modulated crystal structure as well as the photoluminescence properties of Eu 2+ -activated Ca 2 SiO 4 solid solution, the chemical formula of which is (Ca 1.88 Eu 2+ 0.01 □ 0.11 )-(Si 0.78 P 0.22 )O 4 , where □ denotes vacancies in Ca sites with the replacement of Si 4+ by P 5+ . The emission spectrum upon the 335 nm excitation showed a relatively broad band centered at ca. 490 nm and a full width at half-maximum of ca. 80 nm. The crystal structure was made up of the four types of β-Ca 2 SiO 4 -like layers with one type of interlayer. The incommensurate modulation with superspace group Pnma(0 β 0)00s was induced by the long-range stacking order of these layers. The modulation wavevector was 0.27404(2) × b*, with the basic unit-cell dimensions being a = 0.68355(2) nm, b = 0.54227(2) nm, and c = 0.93840(3) nm (Z = 4). The basic structure contained two nonequivalent Ca sites. One site was fully occupied by Ca 2+ and free from Eu 2+ in the overall incommensurate structure. The occupational modulation at the other site was so significant that the sum of site occupation factors for Ca 2+ and Eu 2+ as low as 0.5 was seen at the interlayer. This site was too large for accommodation of Ca 2+ but was suitable for Eu 2+ . Thus, the Eu 2+ ions would exclusively concentrate at the relevant site, which would cause the emission peak of the incommensurate phase to be shifted to the shorter wavelength ranges as compared with those of the other commensurate phases such as β and α′ L .

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“…Besides, C 2 S has also been extensively studied due to its importance for novel silicate phosphors, the CO 2 capture technology, and bioactive materials . C 2 S has been a promising host material for light-emitting diode phosphors, ,− where the emission spectra are induced by the 5d → 4f transition of doped rare-earth elements such as Eu 2+ ions in the γ-, α L ′ -, α H ′ -, α-, and β-phases. Its emission color is not only dependent on the phase of luminescent ions but also on the host environment .…”

Section: Introductionmentioning

confidence: 98%

P-Doped α-Ca₂SiO₄ and (Si, P)-Codoped CaO with Special Defect Microstructures and Luminescence due to an Enhanced Solid Solution by a Pulsed Laser Ablation Condensation Route

Huang

2021

Crystal Growth & Design

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The α-Ca2SiO4 and rocksalt-type (R) CaO condensates/particulates with an enhanced solid solution of P and Si + P ions, respectively, were produced via pulsed laser ablation of a silicocarnotite (Ca5(PO4)2SiO4) target under a relatively high peak power density of 1.8 × 109 Watt/cm2 in high vacuum (8 × 10–5 torr). The condensates were dispersed in an amorphous phase of Ca–Si–P–O linkage as spheres up to submicrons in size or coalesced in particulates by the {100}R, {111}R, and {1̅21̅0}α facets to follow a preferred crystallographic relationship of (1̅1̅1)R//(1̅21̅0)α; [101]R//[101̅1]α, with a fair three-dimensional match of the lattice planes. The 1-D commensurate superstructures n × (200)R and n × (1̅21̅0)a, where n = 1.5 and 3, were commonly noted for the condensates in the particulates. The P-doped α-Ca2SiO4 and (Si, P)-codoped CaO showed characteristic luminescence at 407 and 537 nm, respectively, under the combined influences of internal compressive stress as well as substitutional and/or interstitial defects with charge/volume-compensating cation vacancies for potential optoelectronic and photocatalytic applications.

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Enhancement of PL intensity and formation of core-shell structure in annealed Ca 2-x/2 (Si 1-x P x )O 4 :Eu 2+ phosphor

Cited by 8 publications

References 16 publications

The Effect of Heat Treatment on the Emission Color of P-Doped Ca2SiO4 Phosphor

The Effect of Heat Treatment on the Emission Color of P-Doped Ca2SiO4 Phosphor

Crystal Structure and Photoluminescence Properties of an Incommensurate Phase in EuO- and P₂O₅-Doped Ca₂SiO₄

P-Doped α-Ca₂SiO₄ and (Si, P)-Codoped CaO with Special Defect Microstructures and Luminescence due to an Enhanced Solid Solution by a Pulsed Laser Ablation Condensation Route

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Enhancement of PL intensity and formation of core-shell structure in annealed Ca 2-x/2 (Si 1-x P x )O 4 :Eu 2+ phosphor

Cited by 8 publications

References 16 publications

The Effect of Heat Treatment on the Emission Color of P-Doped Ca2SiO4 Phosphor

The Effect of Heat Treatment on the Emission Color of P-Doped Ca2SiO4 Phosphor

Crystal Structure and Photoluminescence Properties of an Incommensurate Phase in EuO- and P2O5-Doped Ca2SiO4

P-Doped α-Ca2SiO4 and (Si, P)-Codoped CaO with Special Defect Microstructures and Luminescence due to an Enhanced Solid Solution by a Pulsed Laser Ablation Condensation Route

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Crystal Structure and Photoluminescence Properties of an Incommensurate Phase in EuO- and P₂O₅-Doped Ca₂SiO₄

P-Doped α-Ca₂SiO₄ and (Si, P)-Codoped CaO with Special Defect Microstructures and Luminescence due to an Enhanced Solid Solution by a Pulsed Laser Ablation Condensation Route