OPTICAL MATERIALS
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2024
·
IF 3.8
Yanbin Wang,Ziqiu Cheng,Junhao Ye,Haohong Chen,Chen Hu,Zhenzhen Zhou,Yuyang Chen,Yudie Yang,Denis Yu Kosyanov,Jiang Li
Based on the “effective ionic radius match effect” and the “charge balance substitution rule of ions”, mixed Ba 2+ , Al 3+ , Lu 3+ , and Ce 3+ ions can be effectively regulated to a BaAl 2 O 4 -LuAG:Ce biphasic structure. The contribution of BaAl 2 O 4 like as scattering centers can reduce overall reflection losses and enhance the light extraction efficiency of these composite phosphor ceramics (CPCs). In this work, a series of x wt.% BaAl 2 O 4 -LuAG:Ce ( x = 0, 3, 5, 10, 15) CPCs were fabricated by vacuum sintering using co-precipitated composite powders. Homogenization at the atomic level of mixed Ba 3+ , Al 3+ , Lu 3+ , and Ce 3+ ions in multiphase powders provides uniform distribution of BaAl 2 O 4 and LuAG:Ce constituent phases in composite ceramics. The introduction of BaAl 2 O 4 has an additive effect, which also consists in uniform aggregation of pores near their grains during sintering. It allows to adjust the size and amount of microstructural defects by varying the secondary phase content. Under the excitation of 10.8 W 450 nm LDs in a reflection mode, 3 wt% BaAl 2 O 4 -based CPCs show the optimum luminous flux of 2244 lm and a luminous efficiency of 208 lm·W −1 . The obtained CPCs show a high application potential in solid-state laser lighting.
研究领域:
材料科学
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光学工程
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DOI
高影响因子
LUMINESCENCE
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2024
·Vol. 39
·期 7
·e4836
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IF 3.2
Guoxiang Song,Chaogang Lou,Ruiqi Zhu,Han Diao,Bowen Shen
The near-infrared (NIR) down-conversion process for broadband sensitization has been studied in Eu 2+ -Nd 3+ co-doped BaAl 2 O 4 . This material has a broad absorption band of 200–480 nm and can convert photons in the visible region into NIR photons. The NIR emission at 1064 nm, attributed to the Nd 3+ : 4 F 3/2 → 4 I 11/2 transition, matches the bandgap of Si, allowing Si solar cells to utilize the solar spectrum better. The energy transfer (ET) process between Eu 2+ and Nd 3+ was demonstrated using photoluminescence spectra and luminescence decay curves, and Eu 2+ may transfer energy to Nd 3+ through the cooperative energy transfer (CET) to achieve the down-conversion process. The energy transfer efficiency (ETE) and theoretical quantum efficiency (QE) were 68.61% and 156.34%, respectively, when 4 mol% Nd 3+ was introduced. The results indicate that BaAl 2 O 4 :Eu 2+ -Nd 3+ can serve as a potential modulator of the solar spectrum and is expected to be applied to Si solar cells.
研究领域:
材料科学
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光电技术
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可再生能源
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光子学
✓ 已验证
DOI
高影响因子
Journal of Energy Chemistry
·
2025
·
IF 14.9
Qiangqiang Xue,Kang Hui Lim,Zhehao Sun,Binhang Yan,Zongyou Yin,Ange Nzihou,Yujun Wang,Guangsheng Luo,Feng-Shou Xiao,Sibudjing Kawi
Dry reforming of methane (DRM) over Ni-based catalysts is an economically reasonable technology for large-scale CO 2 utilization. However, prolonged Ni sintering and carbon deposition reduce the durability and efficiency of DRM, hindering its engineering application. Herein, we propose a facile approach by combining continuous microscale coprecipitation with solid-state reactions to construct a BaAl 2 O 4 -overlayer-confined Ni catalyst. The 5-wt.%-Ni@BaAl 2 O 4 catalyst exhibited advanced CO 2 and CH 4 conversions of 96% and 86% at 800 °C and a GHSV of 144 L∙g cat. −1 ∙h −1 . Moreover, the k d -CO 2 and k d -CH 4 of Ni@BaAl 2 O 4 were 0.0063 and 0.0029 h −1 ; which are approximately half and one-thirds of those of Ni/BaAl 2 O 4 and slightly better than those of Ni@MgAl 2 O 4 , underscoring the versatility of the proposed synthesis protocol for constructing core–shell structures. XAS, HAADF–STEM–EDS, and CO transmission-IR characterizations confirmed the SMSI of ∼2-nm amorphous BaAl 2 O 4 -overlaid ∼10 nm Ni with an overall mesoporous structure. After a long-term test, the sintering and coking inhibition effects of Ni@BaAl 2 O 4 (10 → 11 nm, 0.55 mg C ∙g cat. −1 ∙h −1 ) outperformed Ni/BaAl 2 O 4 (13 → 22 nm, 1.90 mg C ∙g cat. −1 ∙h −1 ) and Ni@MgAl 2 O 4 . In situ time-resolved CH 4 → CO 2 transient response, DRIFTS experiments, and DFT calculations suggested that Ni@BaAl 2 O 4 and Ni/BaAl 2 O 4 followed the Mars–van Krevelen and Langmuir–Hinshelwood redox mechanisms, respectively. The functional interfacial lattice oxygen promoted the removal of C ads * on Ni and core–shell structure induced fast CO 2 adsorption and CO desorption. The present study provides a facile approach for constructing a stable and active Ni-based core−shell catalyst. Furthermore, it offers novel insights into the functionalities of non-reducible spinel overlayers in the DRM process.
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产品关联
DOI
高影响因子
ACTA MATERIALIA
·
2023
·
IF 9.4
Junyan Gao,Peng Liu,Jinshu Wang,Ruimin Zhang,Yunfei Yang,Wenyuan Zhou,Hexiong Liu,Junhao Sun
The size and distribution of Sc 2 O 3 in the composite powder precursor has great effect on the emission property of scandate cathode. By one-step in-situ synthesis method, the composite powder exhibits the structure of quasi-spherical Sc 2 O 3 nanoparticles grown in situ on the surface of W/Ir grains, and the obtained W–Ir cathode with 3wt % Sc 2 O 3 could provide the emission current density of 83.43 A/cm 2 at 900 °C b , which is higher than other W–Ir mixed matrix scandate cathodes and W matrix scandate cathode. The XRD results showed that the high emission ability depended on the high content of active phase α-Ba 2 ScAlO 5 and low content of non-active phase BaAl 2 O 4 . In-situ TEM has been applied to observe the microstructure evolution of the cathode surface at high temperature for the first time. A serial change in the microstructural features of cathode surface and the migration of Ba, Sc and O on the substrate surface has been found, confirming the formation of Ba-Sc-O active layer. The first-principles calculations indicate that the active substances (Sc) are more stable (low adsorption energy of − 8.58 eV) on the IrW matrix cathode surface than on the tungsten matrix cathode surface, which is consistent with the low evaporation rate of the active substance detected by TFMS technique. Besides, the interaction between the active substance and the matrix was strengthened due to more electron transfer of Sc (1.88 e) and Ba (1.45 e), therefore lowering the work function . The feasible preparation technique makes such a cathode promising for applications in high-power microwave devices.
研究领域:
材料科学
·
电子工程
·
表面科学
·
纳米技术
✓ 已验证
DOI
高影响因子
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