POLYMER
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2025
·
IF 4.5
Yifan Chen,Wentao Yuan,Yingxin Zhang,Hu-jun Qian,Zhong-yuan Lu,Shuxun Cui
According to the principle of polymer science, the gelation process of κ-carrageenan should start with polymer chains in a disordered coil conformation. However, the coil-helix model has been challenged by recent studies, which pointed out that in deionized water, κ-carrageenan exists in single-helix conformation rather than random coil. Here, we employ single-molecule force spectroscopy (SMFS) to investigate its conformation under different conditions at the single-chain level. Direct evidence for the existence of random coil state is obtained. In addition, it is found that coil-single helix transition can be induced by external Na + ions, which can screen the charges of the sulfated groups in κ-carrageenan. Thus, the mechanism of the first step of κ-carrageenan gelation is revealed, which lays a solid foundation for better understanding of the entire gelation process.
研究领域:
高分子科学
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生物物理学
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食品科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2018
·Vol. 6
·期 20
·5453-5461
·
IF 5.976
Shaohua Fan,Guojun Gao,Shiyu Sun,Sijun Fan,Hongtao Sun,Lili Hu
Absolute quantum efficiency (QE) of up-conversion (UC) materials is still limited to ∼3%, which strongly limits their applications in many areas. Herein, we report highly efficient UC β-NaYF4:Yb3+,Er3+ micro-cylinders prepared via a newly developed Li+/Na+ ion exchange method (IEM) with absolute QE as high as ∼4.0%. A small amount of Li+ is interstitially incorporated in β-NaYF4:Yb3+,Er3+, which not only maintains well the micro-cylindrical morphology but also enhances the emission intensity by ∼40%, doubles absolute UCQE (∼3.0% under a fixed excitation power density of 15 W cm−2), and prolongs the lifetime. The UC excitation profile is composed of a sharp peak at 976 nm and a weak shoulder at 935 nm. The absolute UCQE of Li+/Na+ IEM β-NaYF4:Yb3+,Er3+ is systemically studied over a wide excitation power density of 0.4–100 W cm−2, and we obtained impressively high UCQE of 4.0% under 60 W cm−2 power density, which is among the highest values in the literature. The application of two green UC emissions of Li+/Na+ IEM β-NaYF4:Yb3+,Er3+ in ratiometric thermometers is successfully demonstrated. The high relative temperature sensitivity (SR) of 1113/T2 and excellent repeatability as indicated by three heating–cooling cycles (293–753 K) suggest their promising application as a temperature sensor.
研究领域:
材料科学
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光学
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纳米技术
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
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IF 5.2
Yixuan Zhao,Lu Liu,Li Zhou,Ruiqi Yang,Changlin Li,Jiexin Chen,Ziyue Hu,Haoran Su,Bin Deng,Xiaohui Ji,Ruijin Yu
New Sm 3+ doped Cd 2 MgTeO 6 tellurate red-emitting phosphors with Na + ions as charge compensation were obtained using a high-temperature solid-state approach at 1000 °C. During this study, the prepared phosphors were subjected to phase purity, particle morphology , luminescence characteristics, thermal stability, and Commission Internationale de L′ Eclairage (CIE) chromaticity. The critical quenching concentration of Sm 3+ doped Cd 2 MgTeO 6 phosphor was 2 mol%. According to Dexter's theory and the calculated R c value (22.21 Å), the dipole-dipole interaction causes the phenomenon of concentration quenching. Particularly, the Cd 2 MgTeO 6 :2 mol%Sm 3+ , 2 mol%Na + phosphor exhibited an evident red-light emission (647 nm) at λ ex = 407 nm because of the 4 G 5/2 to 6 H 9/2 level transition of Sm 3+ . Its internal quantum efficiency (IQE) was 38.87%. It is worth noting that the Cd 2 MgTeO 6 :Sm 3+ , Na + phosphor exhibited abnormal thermal quenching (ATQ) characteristics, and the luminous intensity of the Cd 2 MgTeO 6 :2 mol%Sm 3+ , 2 mol%Na + increased by 7.20% at 480 K compared with the initial temperature. In addition, white LEDs and red LEDs were successfully manufactured with a 408 nm chip. The prepared red LED showed the emission spectrum similar to the absorption spectrum of Phytochrome P r , which is expected to be applied in plant growth. The w-LED had a CCT (correlated color temperature) of 4790 K, color rendering index of 91, and color coordinates of (0.348, 0.335). Therefore, the Cd 2 MgTeO 6 :Sm 3+ , Na + phosphor has demonstrated potential applications in w-LEDs and plant growth LEDs.
研究领域:
材料科学
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光学工程
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农业科学
✓ 已验证
产品关联
DOI
高影响因子
Nanomaterials
·
2021
·Vol. 11
·期 8
·2004
·
IF 5.076
Junjiao Li,Jun Xie,Dongchen Li,Lei Yu,Chaowei Xu,Senlin Yan,Yuzheng Lu
Interface engineering can be used to tune the properties of heterostructure materials at an atomic level, yielding exceptional final physical properties. In this work, we synthesized a heterostructure of a p-type semiconductor (NiO) and an n-type semiconductor (CeO2) for solid oxide fuel cell electrolytes. The CeO2-NiO heterostructure exhibited high ionic conductivity of 0.2 S cm−1at 530 °C, which was further improved to 0.29 S cm−1by the introduction of Na+ions. When it was applied in the fuel cell, an excellent power density of 571 mW cm−1was obtained, indicating that the CeO2-NiO heterostructure can provide favorable electrolyte functionality. The prepared CeO2-NiO heterostructures possessed both proton and oxygen ionic conductivities, with oxygen ionic conductivity dominating the fuel cell reaction. Further investigations in terms of electrical conductivity and electrode polarization, a proton and oxygen ionic co-conducting mechanism, and a mechanism for blocking electron transport showed that the reconstruction of the energy band at the interfaces was responsible for the enhanced ionic conductivity and cell power output. This work presents a new methodology and scientific understanding of semiconductor-based heterostructures for advanced ceramic fuel cells.
研究领域:
材料科学
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能源技术
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电化学
✓ 已验证
DOI
高影响因子
SOLID STATE COMMUNICATIONS
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2023
·
IF 2.1
Zhigang Li,Yuanjie Sun,Hongtao Zhao
Lead free double perovskite nanocrystals is an ideal alternate considering its nontoxic and stable property comparing with their counterpart lead halide perovskite NCs. A simple solution synthesis strategy was used to prepare lead-free double perovskite Cs 2 AgBiBr 6 nanocrystals (NCs) doped with Na ions , resulting in NCs with a monodisperse state, homogeneous morphology, and good crystallinity . By adjusting the amount of Na + doping, the band gap of the NCs was significantly increased from 2.57 eV to 3.00 eV. Furthermore, the relatively low value of photoluminescence quantum yield (PLQY) in the original Cs 2 AgBiBr 6 NCs (∼0.5%) was increased to about 8.5% when doped with 60% Na + . Additionally, the exciton lifetime of the NCs was extended to 16.15 ns compared to the original 2 ns. As a result, the doping of Na + significantly enhanced the PLQY of Cs 2 AgBiBr 6 NCs, indicating their potential value for use in optoelectronic devices .
研究领域:
材料科学
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光学
✓ 已验证
产品关联
DOI
高影响因子
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