Synthesis, characterization and photoluminescence properties of (Gd0.99,Pr0.01)2O2S sub-microphosphor by homogeneous precipitation method

Kou

et al. 2015

J. Am. Ceram. Soc.

Gd 2 O 2 S: Pr ceramics were fabricated by spark plasma sintering using the powders synthesized by carbothermal reduction method. The calcination temperature, carbon content, and other preparation conditions of the powders are optimized. The results indicate that the carbon content in the raw mixture has a great influence on the final phases of the phosphor powders. A possible reaction process and mechanism are also proposed. The spectroscopic properties of Gd 2 O 2 S: Pr phosphors and ceramics are studied by the photoluminescence (PL) and X-ray excitation luminescence (XEL) spectra, in which show a green emission at 513 nm was detected as the main emission under the UV and X-ray excitation.

“…The emission intensity of different samples has the same tendency with the excitation spectra. In addition, all the data are perfect agreement with the references …”

Section: Resultssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Gd₂O₂S: Pr Scintillation Ceramics from Powder Synthesized by a Novel Carbothermal Reduction Method

Kou

et al. 2015

J. Am. Ceram. Soc.

“…Rare‐earth oxysulfides (RE 2 O 2 S) are drawing wide attention for magnetic, catalytic, oxygen storage, luminescent, scintillation, and biological applications, because of their wide‐bandgap (∼4.6‐4.8 eV), low phonon energy (∼520 cm −1 ), good chemical and thermal stability, and low toxicity. Gd 2 O 2 S is of particular research interest among the series since Gd 3+ possesses the highest magnetic monument by its largest number (7) of unpaired electrons among the RE 3+ , which makes Gd 2 O 2 S one of the choices as T1 contrast agent in magnetic resonance imaging (MRI) .…”

Section: Introductionmentioning

confidence: 99%

Photo/cathodoluminescence and stability of Gd₂O₂S:Tb,Pr green phosphor hexagons calcined from layered hydroxide sulfate

et al. 2018

J Am Ceram Soc

Hydrothermal reaction at 150°C and pH = 10 for 24 hours crystallized (Gd,RE)2(OH)4SO4 layered hydroxide sulfate (monoclinic structure; RE = Pr, Tb), from which Gd2O2S:RE (hexagonal structure) green phosphor hexagons were derived via facile dehydration in flowing H2 at 1200°C. Rietveld refinement of the XRD patterns yielded cell dimensions that confirmed the direct crystallization of solid solution. Photoluminescence (PL) study at room temperature found absolute quantum yields of ~25.1% and 28.4%, CIE chromaticity coordinates of (0.145, 0.679) and (0.326, 0.566), and fluorescence lifetimes of ~2.36 μs and 1.21 ms for Pr3+ and Tb3+ under 300 and 275 nm UV excitations, respectively. Temperature‐dependent PL analysis (25‐200°C) indicated that both the Pr3+‐ and Tb3+‐doped phosphors have favorably good thermal stability and retained ~65% and 80% at 100°C and ~41% and 47% at 200°C of their initial emission intensities, respectively. The activation energy for the thermal quenching of PL was determined to be ~0.221 (Pr3+) and 0.314 eV (Tb3+). Cathodoluminescence (CL) found that both the phosphors exhibit increasingly higher emission intensity/brightness at a higher acceleration voltage (up to 7 kV) or beam current (up to 50 μA) and are stable under electron bombardment in the studied range. Raising beam current was suggested to be more effective to enhance CL.

“…Sulfurization of RE 2 O 3 by H 2 S or CS 2 gas at an elevated temperature [24–26] is another frequently used strategy to produce RE 2 O 2 S. Since the methodology for controlled synthesis of RE 2 O 3 is rich and well developed, RE 2 O 2 S with various particle morphologies has thus been produced through the sulfurization route, though the complicated procedures are less feasible for industrial production. Other techniques for RE 2 O 2 S synthesis may include precipitation [27], hydrothermal reaction [28], two-step solution gel polymer thermolysis [29], gelatin-templated synthesis [30], gel thermolysis [31], solvothermal pressure-relief synthesis [32], and combustion [33]. The involvement of harmful sulfur sources or by-products (such as C 2 S, H 2 S, and thiourea) is, however, still hard to avoid.…”

Section: Introductionmentioning

confidence: 99%

(La0.97RE0.01Yb0.02)2O2S Nanophosphors Converted from Layered Hydroxyl Sulfate and Investigation of Upconversion Photoluminescence (RE=Ho, Er)

Liu

et al. 2017

Nanoscale Res Lett

Self Cite

Phase-pure (La0.97RE0.01Yb0.02)2O2S upconversion (UC) nanophosphors (average crystallite size ~ 45 nm; RE=Ho, Er) were annealed from their hydrothermally crystallized layered hydroxyl sulfate precursors in flowing hydrogen at 1200 °C for 1 h, with water vapor as the only exhaust. Under 978-nm laser excitation (up to 2.0 W), the Ho3+-doped phosphor exhibited green (medium), red (weak), and near-infrared (strong) emissions at ~ 546 (5F4 → 5I8), 658 (5F7 → 5I8), and 763 nm (5F4 → 5I7), respectively, and has the stable chromaticity coordinates of about (0.30, 0.66) in the visible-light region (400–700 nm). The Er3+-doped UC phosphor, on the other hand, showed weak green (~ 527/549 nm, 2H11/2,4S3/2 → 4I15/2), weak red (~668/672 nm, 4F9/2 → 4I15/2), and strong near-infrared (~ 807/58 nm, 4I9/2 → 4I15/2) luminescence, whose emission color in the visible region drifted from yellowish-green [(0.36, 0.61)] to green [(0.32, 0.64)] with increasing excitation power. Analysis of the power-dependent UC luminescence found three- and two-photon processes for RE=Ho and Er, respectively, and the possible UC mechanisms were proposed.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-017-2277-4) contains supplementary material, which is available to authorized users.