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排序方式: 共有1279条查询结果,搜索用时 31 毫秒
1.
《Ceramics International》2015,41(7):8614-8622
SnO2–ZnO nanocomposite thin films, prepared by a simple carbothermal reduction based vapor deposition method, were irradiated with 8 MeV Si3+ ions for engineering the morphological and optical properties. The surface morphology of the nanocomposites was studied by atomic force microscopy (AFM), while the optical properties were investigated by photoluminescence spectroscopy (PL) and Raman spectroscopy. AFM studies on the irradiated samples revealed growth of nanoparticles at lower fluence and a significant change in surface morphology leading to the formation of nanosheets and their aggregates at higher fluences. A tentative mechanism underlying the observed ion induced evolution of surface morphology of SnO2–ZnO nanocomposite is proposed. PL studies revealed strong enhancement in the UV emissions from the nanocomposite thin film at lower fluence, while a drastic decrease in the UV emissions along with a significant enhancement in the defect emissions has been observed at higher fluences. 相似文献
2.
Three novel lanthanide polymers, [Ln(III)(L)3EtOH]n (Ln = Tb(1), Ho(2), Er(3), HL = 2,3,5-trichlorobenzoic acid), have been solvothermal synthesized and characterized by single-crystal X-ray diffraction, infrared spectroscopy and element analyses. The three polymers crystallize in triclinic space group P-1. The Ln(III) ions are in turn bridged by double and quadruple carboxylate of L− ligands to form one-dimensional (1D) chains. Magnetic studies reveal that polymer 1 demonstrates dominant ferromagnetic behavior, polymer 2 shows antiferromagnetic behavior, and polymer 3 present spin-canting behavior. 相似文献
3.
《International Journal of Hydrogen Energy》2020,45(53):28860-28869
Developing highly active, stable and sustainable electrocatalysts for overall water splitting is of great importance to generate renewable H2 for fuel cells. Herein, we report the synthesis of electrocatalytically active, nickel foam-supported, spherical core-shell Fe-poly(tetraphenylporphyrin)/Ni-poly(tetraphenylporphyrin) microparticles (FeTPP@NiTPP/NF). We also show that FeTPP@NiTPP/NF exhibits efficient bifunctional electrocatalytic properties toward both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Electrochemical tests in KOH solution (1 M) reveal that FeTPP@NiTPP/NF electrocatalyzes the OER with 100 mA cm−2 at an overpotential of 302 mV and the HER with 10 mA cm−2 at an overpotential of 170 mV. Notably also, its catalytic performance for OER is better than that of RuO2, the benchmark OER catalyst. Although its catalytic activity for HER is slightly lower than that of Pt/C (the benchmark HER electrocatalyst), it shows greater stability than the latter during the reaction. The material also exhibits electrocatalytic activity for overall water splitting reaction at a current density of 10 mA cm−2 with a cell voltage of 1.58 V, along with a good recovery property. Additionally, the work demonstrates a new synthetic strategy to an efficient, noble metal-free-coordinated covalent organic framework (COF)-based, bifunctional electrocatalyst for water splitting. 相似文献
4.
《Optical Fiber Technology》2006,12(3):238-242
We measure the system impacts due to the amplitude of group-delay (GD) ripple in single and cascaded chirped fiber Bragg gratings (CFBGs). Signals with smaller pulse width result in smaller performance variation at the same data rate. A 65-ps peak-to-peak GD ripple induces 0.9, 1.7, and 2.7 dB maximum penalties for 10, 20, and 40-Gb/s, respectively. We also find that cascading gratings with random ripple causes much less degradation than cascading gratings with the same ripple profile. 相似文献
5.
《Optical Materials》2005,27(1):99-102
The spin Hamiltonian parameters g∥, g⊥, A∥ and A⊥ for Er3+ ion in LiYF4 are investigated by using the perturbation formulas of these parameters for a 4f11 ion in tetragonal symmetry. In these formulas, the contributions to the spin Hamiltonian parameters from the second-order perturbation terms and the admixtures of different states are considered. The relevant crystal field parameters are calculated from the superposition model and the local structural parameters of the Y3+ site occupied by impurity Er3+. The theoretical optical spectra within 4I15/2 and 4I13/2 states and the spin Hamiltonian parameters obtained in this work are consistent with the observed values. 相似文献
6.
7.
《Journal of the European Ceramic Society》2006,26(6):967-980
Through a study of Ni–YSZ interfaces it is shown that time-of-flight-secondary ion mass spectrometry (TOF-SIMS) is a powerful and convenient tool for the analysis of ultra thin layers of segregated material at the interfaces and on free surfaces. Two different types of Ni, “pure Ni” (99.995% Ni) and “impure Ni” (99.8% Ni) were investigated. The contact areas on the YSZ and areas outside the contacts were examined with XPS and TOF-SIMS. The impure nickel causes a relatively larger amount of impurities to accumulate at the contact area, e.g. oxides of Mn, Ti, Si and Na. Some impurities migrate to the area outside the contact area. Even though on a larger scale the impurities seem to be homogeneously distributed, detailed analyses in and outside the contact area show the presence of impurity particles, and that the surface species are inhomogeneously distributed amongst the different grains. The extremely low detection limit, the small probe depth, the image capability, and the ease of elemental identification make TOF-SIMS an obvious choice as an analytical tool for studying segregation phenomena at metal–ceramic interfaces such as Ni–YSZ interfaces. XPS, being a quantitative technique, was used as a complementary technique to TOF-SIMS, which is not directly a quantitative technique. 相似文献
8.
In order to develop highly efficient upconversion (UC) material, Er3+-doped oxyfluoride glass ceramics containing BaYF5 nano-crystals were fabricated for the first time. The randomly distributed BaYF5 nano-particles with the size of nearly 25 nm precipitated from the glass matrix at about 700 °C, then tended to aggregate slightly with the increase of heating temperature, resulting in the enhancement of Er3+ UC emission in the wavelength ranging from 500 nm to 700 nm. The UC process was found very sensitive to Er3+ content: with the increase of Er3+ content from 0.5% to 1.0%, the UC intensity behaved with drastic exaltation; while further increasing Er3+ content to 2.0% resulted in a notable fluorescence quenching. Significantly, the UC efficiency of present glass ceramic preponderates notably over that of the previously reported glass ceramic containing LaF3, implying its superior UC potentiality. 相似文献
9.
Catalysis Letters - Pd-based heterogeneous nanocatalysts have wide application in chemical industry. However, the traditional synthesis process contains multi-steps such as impregnation, dry,... 相似文献
10.
《中国稀土学报(英文版)》2022,40(10):1519-1526
Lanthanide doped fluorescent nanoparticles have gained considerable attention in biomedical applications. However, the low uptake efficiency of nanoparticles by cells has limited their applications. In this work, we demonstrate how the uptake efficiency is affected by the size of nanoparticles under flow conditions. Using the same size NaYF4:20% Yb3+,2% Er3+,2% Ce3+ (the contents of rare earths elements are in molar fraction) nanoparticles as core, NaYF4:20% Yb3+,2% Er3+,2% Ce3+@NaYF4 core–shell structured nanorods (NRs) with different sizes of 60–224 nm were synthesized by thermal decomposition and hot injection method. Under excitation at 980 nm, a strong upconversion green emission (541 nm, 2H11/2 → 4I15/2 of Er3+) is observed for all samples. The emission intensity for each size nanorod was calibrated and is found to depend on the width of NRs. Under flow conditions, the nanorods with 96 nm show a maximum uptake efficiency by endothelial cells. This work demonstrates the importance of optimizing the size for improving the uptake efficiency of lanthanide-doped nanoparticles. 相似文献