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1 of 6) 1600568 dielectric function. Alloying of these noble metals has been applied to tune the material dielectric function, where the LSPR can be modulated progressively from the UV (pure Ag) to the NIR (pure Au). [12][13][14][15] Thus, metallic nanostructures composed of Ag-Au can enable the rational design of building blocks for different applications, such as metamaterials, [16,17] hot carrier devices, [18] light absorption improvement in photovoltaics, [19,20] colored glasses, [21] displays, [22,23] and catalysis. [24] To date, different fabrication techniques have been successfully utilized to realize Ag x Au 1−x alloyed NPs. They can be formed by colloidal synthesis via the reduction of precursors containing metals in solution, [25,26] and by the sequential pulsed laser deposition of Ag and Au targets, [27,28] which can yield large amounts of NPs with narrow size distribution. However, the overall size of the NPs cannot be varied beyond 150 nm. [29] Alternatively, nanolithographic methods enable full control of NPs size, shape, and distribution. [13] Nevertheless, this technique is constrained to specific applications due to its high cost and very limited scalability. The dewetting of metallic thin films has also been used to fabricate pure [21,[30][31][32] and alloyed [19] metal NPs. In this simple and effective fabrication route, a very thin layer of metal (<50 nm) is initially deposited onto a substrate. Then, when the thin-film sample is annealed under a controlled environment (oxygen free), surface diffusion takes place and results in the formation of nanostructures to minimize the energy of the system. [33][34][35][36] This method has been particularly useful for optoelectronic devices, where these metallic NPs act as light scattering centers that ultimately increase light absorption within the semiconductor. [4,37] In this work, we fabricate fully alloyed Ag x Au 1−x NPs with controlled chemical composition by dewetting thin films and characterize their optical response at the macro-and nano-scale. Surprisingly, we find that the NPs' distribution heavily depends on the thin-film chemical composition, irrespective of the original film thickness. Simultaneously, we measure a shift of the LSPR due to the NPs' composition variation, which defines their optical response. We map the elemental distribution of Ag and Au and confirm that the NPs are fully alloyed, forming a solid solution at the nanoscale. To further illustrate how the chemical composition affects the material optical response, we perform a detailed analysis of the optical characteristics of fully alloyed Ag 0.5 Au 0.5 nanostructures in the visible range of the spectrum. For that, we combine spectrally dependent NSOM measurements and finite-difference time-domain (FDTD) simulations to locally resolve the optical response of individual NPs. Our results of the near-field light-matter interactions for Ag 0.5 Au 0.5 nanostructures reveal an electric field enhancement of 30 times in the visible range of the spectrum under the NPs Combining meta...

We present a systematic characterization of the transition layer at the 4H-SiC/SiO 2 interface as a function of nitric oxide (NO) post-annealing time, using high-resolution transmission electron microscopy for structural characterization and spatially resolved electron energy-loss spectroscopy for chemical analysis. We propose a systematic method for determining transition layer width by measuring the monotonic chemical shift of the Si-L 2,3 edge across the interface, and compare its efficacy to traditional measures from the literature, revealing the proposed method to be most reliable. A gradual shift in the Si-L 2,3 edge onset energy suggests mixed Si-C/Si-O bonding in the transition layer. We confirm an inverse relationship between NO-anneal time and transition layer width, which correlates with improved channel mobility, enhanced N density at the interface, and decreased interface trap density. No excess C was noted in the interfacial region. V

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The impact of sintering temperature on Cr-poisoning of solid oxide fuel cell (SOFC) cathodes was systematically studied. La 0.6 Sr 0.4 Fe 0.8 Co 0.2 O 3-δ -Ce 0.9 Gd 0.1 O 2-δ symmetric cells were aged at 750 • C in synthetic air with the presence of Crofer 22 APU, a common high temperature interconnect, over 200 hours and electrochemical impedance spectroscopy (EIS) was used to determine the degradation process. Both the ohmic resistance (R ) and polarization resistance (R P ) of LSCF-GDC cells, extracted from EIS spectra, for different sintering temperatures increase as a function of aging time. Furthermore, the Cr-related degradation rate increases with decreased cathode sintering temperature. The polarization resistance of cathode sintered at lower temperature (950 • C) increases dramatically while aging with the presence of Cr and also significantly decreases the oxygen partial pressure dependence after aging. The degradation rate shows a positive correlation to the concentration of Cr. The results indicate that decreased sintering temperature increases the total surface area, leading to more available sites for Sr-Cr-O nucleation and thus greater Cr degradation. The growing demand for robust, inexpensive, clean, secure, and sustainable energy have stimulated great interest in fuel cells. Among all types, solid oxide fuel cells (SOFCs) are one of the most promising candidates due to high efficiency and fuel flexibility.1-4 Recently, significant effort has been devoted to the development of intermediate to low temperature (400-800• C) SOFCs. Lowing operating temperature not only decreases the degradation rates but also broadens the selections of materials. The mixed ionic and electronic conducting (MIEC) perovskite La 0.6 Sr 0.4 Fe 0.8 Co 0.2 O 3-δ (LSCF) and its composite with Ce 0.9 Gd 0.1 O 2-δ (GDC) is a promising cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs) because of its high intrinsic electrocatalytic activity to the oxygen reduction reaction (ORR) and acceptable thermal expansion coefficient. However, one of the challenges for the commercialization is the durability during long-term operation. [5][6][7][8][9] One of the most severe issues for cathode degradation is Cr-poisoning from Cr-containing stainless steel interconnects at high temperatures. Significant efforts have been given to understand the Cr-degradation mechanisms on SOFC cathodes. Jiang et al. [10][11][12] shows that gaseous Cr species can be chemically reduced and deposited at triple phase boundaries (TPB) as well as two-phase boundaries, blocking sites active toward the ORR. [10][11][12] The activity of the ORR on cathodes is governed by several factors, such as the atomic structure, surface composition 13-15 and bulk microstructure. In this research, sintering effect on Cr-degradation on LSCF-GDC was studied. Small changes in cathode sintering temperature leads to distinct differences in degradation rates for LSCF-GDC composite cathodes exposed to Cr-containing interconnect materials. Elevated cathode sinteri...