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Okamoto, Tokuhiko; Ukyo, Yoshio

doi:10.1023/a:1018525728259

Cited by 7 publications

(4 citation statements)

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“…The PL intensity fell off to 19% by further heating to 300 °C, while it recovered completely the initial value upon cooling, showing the high thermal stability of the host lattice itself. By considering the high lattice rigidity (i.e., low thermal expansion , ) and the consequent smaller Stokes shift (SS) in the current system, the observed thermal quenching might mainly result from the ionization of excited 5d electron of Eu 2+ into the conduction band, caused by the remarkable decrease of the E g value. The occurrence of photoionization is also suggested by the decreased emission efficiency under the excitation below ∼350 nm region, as indicated by the PL excitation spectrum shown in Figure .…”

Section: Resultsmentioning

confidence: 93%

Powder Synthesis of Y-α-SiAlON and Its Potential as a Phosphor Host

et al. 2009

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The Y-α-SiAlON fine powders have been successfully synthesized from the system Y2O3−Al2O3−SiO2, by using the gas-reduction−nitridation method. Completion of the nitridation was achieved at temperatures <1500 °C without unfavorable carbon contamination and SiC formation. While the presence of Y-containing intermediate phases inhibited the formation of pure α′ phase in the as-synthesized state, transient liquid-phase formation promoted under the postsynthesis heat treatment enabled the preparation of near single-phase Y-α-SiAlON powders. The synthesized Y-α-SiAlON:Eu2+ powder exhibited a bright orange emission under near-UV to blue light excitation showing the applicability to the phosphor-converted white light-emitting diodes, whereas the quantum efficiency and the thermal stability were found to be low compared to the Ca-stabilized analogue. The first-principles calculations on the electronic structures of Y- and Ca-α-SiAlON:Eu2+ were performed for the first time, which clearly demonstrated the effects of modifying cations on their photoluminescent properties.

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Section: Resultsmentioning

confidence: 93%

Powder Synthesis of Y-α-SiAlON and Its Potential as a Phosphor Host

et al. 2009

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“…Such α-SiAlON ceramics are thermally durable. 9,10 In recent years, they have been used as phosphors with luminescence corresponding to rare-earth ions such as Eu 2+ , Tb 3+ , Yb 2+ , and Er 3+ . [11][12][13][14][15] Because solitary Ce 3+ does not stabilize α-SiAlON, co-doping with stabilizing ions such as Ca 2+ , Y 3+ , and Lu 3+ is performed to obtain α-SiAlON phosphors activated by Ce 3+ .…”

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confidence: 99%

Transparency and Photoluminescence of Gas-Pressure Sintered Lu-α-SiAlON:Ce³⁺ Ceramics

Aminaka

Tatami

Iijima

et al. 2022

ECS J. Solid State Sci. Technol.

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Owing to the growing demand for high power optical devices in several fields such as manufacturing, medicine, and communications, the demand for large and transparent inorganic materials capable of emitting multiple colors is increasing. α-SiAlON, which has excellent thermal and mechanical properties, is a phosphor that emits blue light because of the doping of Ce3+. However, only a few transparent and photoluminescent α-SiAlON:Ce3+ ceramics have been developed. In this study, we fabricated transparent α-SiAlON:Ce3+ ceramics using a gas-pressure sintering technique utilizing Lu3+, which has the smallest ionic radius among the rare-earth ions used to stabilize α-SiAlON. The Lu-α-SiAlON:Ce3+ ceramics exhibited higher transparency than Y-α-SiAlON:Ce3+ because of their finer grain size. The maximum emission wavelength of the Lu-α-SiAlON:Ce3+ ceramics was blue shifted relative to that of the Y-α-SiAlON:Ce3+ ceramics owing to lattice shrinkage. A lower Ce concentration resulted in higher transparency and a blue shift in the maximum emission wavelength. Furthermore, the in-line transmittance of the gas-pressure sintered Lu-α-SiAlON:Ce3+ ceramics using fine raw powders of rare-earth oxides was 50% at 600 nm, which was higher than that of Y-α-SiAlON:Ce3+ ceramics prepared via the same gas-pressure sintering technique followed by hot isostatic pressing.

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“…A common way to increase the oxidation resistance of Mo or Mo-based alloys is to protect the surface by deposition of [106] Al 2 O 3 8.6 [107] B 5.0-7.0 [108] CaMoO 4 13.5/22.8 (*) a) [109] CMAS 9.8 [110] Cr 10.8 [111] CrN 7.16 [112] CrSi 2 16.8/10.9(*) a) [113] Gd 2 Zr 2 O 7 12.4 [114] Mo 5.7 [115] Mo 2 B 5.0 [116] Mo 2 B 5 8.6 [116] Mo 2 N 6.7 [117] Mo 3 Si 7.2 [118] Mo 5 Si 2.97 B 0.16 5.7/13.9 (*) a) [28] Mo 5 Si 3 11.8/5.8 (*) a) [7] Mo 5 SiB 2 7.55 [57] MoB 8.4/6.4 (*) a) [118] MoB 2 7.7 [116] MoSi 2 8.0/10.0 (*) a) [28] Mo-Si-B 5.0-6.0 [28] PHPS (pyrolyzed) 3-4 [86,88] Si 2.6 [119] SiB 6 5.1 [120] SiC 5.1 [121] Si 3 N 4 3.6 [122] SiO 2 0.5-4.1 [28] Steel (fcc) 17 [123] Ti 10.5 [124] TiN 11.0 [125] W 4.6 [126] YSZ 11.7 [127] a)…”

Section: Metallic Coatingsmentioning

confidence: 99%

Oxidation‐Resistant Environmental Barrier Coatings for Mo‐Based Alloys: A Review

et al. 2020

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Molybdenum‐based materials offer high melting temperatures and promising mechanical properties; therefore, they are potential candidates for high‐temperature components, such as turbine blades. However, at temperatures above 700 °C, molybdenum suffers from severe pesting phenomenon, leading to decomposition of the component. Therefore, oxidation‐resistant environmental barrier coatings are crucial to prevent the material from degradation and to maintain its excellent mechanical properties at high temperatures. This review provides a detailed overview on the different coating concepts for Mo and Mo‐based alloys.

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Cited by 7 publications

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Powder Synthesis of Y-α-SiAlON and Its Potential as a Phosphor Host

Powder Synthesis of Y-α-SiAlON and Its Potential as a Phosphor Host

Transparency and Photoluminescence of Gas-Pressure Sintered Lu-α-SiAlON:Ce³⁺ Ceramics

Oxidation‐Resistant Environmental Barrier Coatings for Mo‐Based Alloys: A Review

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Untitled

Cited by 7 publications

References 0 publications

Powder Synthesis of Y-α-SiAlON and Its Potential as a Phosphor Host

Powder Synthesis of Y-α-SiAlON and Its Potential as a Phosphor Host

Transparency and Photoluminescence of Gas-Pressure Sintered Lu-α-SiAlON:Ce3+ Ceramics

Oxidation‐Resistant Environmental Barrier Coatings for Mo‐Based Alloys: A Review

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Transparency and Photoluminescence of Gas-Pressure Sintered Lu-α-SiAlON:Ce³⁺ Ceramics