To open new vistas for designing nanophotonic systems, exploiting high refractive index (RI) availability is now drawing attention worldwide, especially in the visible-infrared range. Based upon the nanoscale close-packed arrangement of metallic nano-units, few optical-frequency metamaterials with high RIs have been demonstrated. However, there are still significant challenges in their RI promotion, tuneability, and integrated preparation for practical applications. Herein, a novel Ag nanowire-based metamaterial scheme is put forward, in which vertically aligned Ag nanowire (NW) array embedded-Si or -Ge composites are made. Thanks to flexible control on microstructure parameters of Ag NWs (meta-unit) and their dielectric environment, the synergistic effect of enhanced capacitive coupling and weakened diamagnetic response is created, leading to a recorded near-infrared high-RI of & AP;7.2, low-dispersion from 2 to 10 & mu;m, and customizable RIs. Further, an air nanohole array-Si composite layer, acting as an impedance matching layer, is utilized to realize the transmittance increase of the metamaterial film by & AP;50% at specific wavelengths, along with the bulk plasmon-polariton (BPP) modes resonances in the interwire nanocavities. This approach to increasing the infrared refractive index can circumvent physical effect conflict in high RI metamaterials and pave a basis for future scalable and on-demand photonic applications.

运用透射电子显微镜对密排六方的纯锌中由变形引发的■孪晶界精细结构进行了表征，发现实际孪晶界会在宏观尺度上大幅偏离理论孪晶面.高分辨透射电子显微镜分析表明，实际孪晶界可以由■共格孪晶面和小段基面/柱面（BP/PB）台阶相互连接组成，也可以仅由一系列相互垂直的BP/PB台阶连接而成.这两种结构不同的孪晶界可以共存于同一个■孪晶中.结合位错理论对两种孪晶界的迁移机制进行了讨论，第一种孪晶界的迁移是通过孪生位错在共格孪晶界上运动和界面位错在BP/PB台阶上运动来实现的，第二种孪晶界则要通过局部晶胞重构机制实现迁移.两种孪晶界的共存可以由孪晶的形核和生长过程解释.

The study aims to understand the irradiation behavior of multilayer coatings composed of high-entropy materials. Here, we report the structural stability and elemental segregation of high-entropy TiNbZrTa/CrFeCoNi metallic and nitride multilayer coatings under 3-MeV Xe20+ ion-irradiation at room temperature and 500 °C, respectively. Transmission electron microscopy analysis shows that the microstructure of nanocrystalline CrFeCoNi high-entropy-alloy sublayers are not stable and readily transforms into amorphous state at 500 °C and/or under irradiation conditions. The elemental distribution, acquired by energy-dispersive X-ray spectroscopy under scanning transmission electron microscopy mode, shows preferential diffusion of Co and Ni into TiNbZrTa sublayers, while Fe and Cr preferentially remain within the previous CrFeCoNi sublayers. TiNbZrTaN/CrFeCoNiNx nitride multilayers exhibit a higher crystallinity and structural stability as well as resistance to diffusion at high-temperature and/or irradiation conditions than their TiNbZrTa/CrFeCoNi metallic multilayer counterparts. These findings are explained by atomic size differences, the difference in Gibbs free energy of the mixing system, and interstitial-solute-induced chemical heterogeneity. Our findings thus provide a design strategy of high entropy nitride for nuclear fuel cladding.

Low refractive index (RI) porous dielectrics at optical frequencies, serving as subwavelength effective media for versatile photonic utilization, still face great challenges in realizing flexible refractive index adjustment, and balancing low RI performance and material robustness. These mainly stem from difficulty in precisely controlling their porosity, as well as high porosity (excessive air exposure) induced refractive index shift and weakened rigidity. To address these issue, ultrafine vertically aligned and perforated air nanocolumn-SiO2 composite films are elaborately designed and fabricated, namely, ultrafine (the diameter < 10 nm) nanoholes embedded in the SiO(2)matrix. The simple preparation process refers to self-organization growth of Ag nanowire (NW) arrays in SiO2 matrix followed by chemical etching for silver removal. Owing to high aspect ratio-induced depolarization effect and porosity modulation, their RIs not only possess anisotropic feature, but also are continuously tunable (from 1.40 to 1.15 for ordinary component and 1.41 to 1.19 for extraordinary component). Due to their low-RI nature and nanoscale microstructural characteristic, broadband (380 nm-1700 nm) high transmittance properties are demonstrated with ultralow (< 0.5%) haze. More importantly, our proposed films are mechanically robust with water-proof and antifouling in nature. This work provides a new scheme for constructing anisotropic low RI materials that should be intriguing for diverse photonic applications.

Aside from well-performed light confinement, practical and scalable plasmonic perfect absorbers also depend on stable material scenario, as well as compact design and convenient fabrication. However, it still remains a challenge to make enclosed (no air exposure), multi-scale plasmonic nanostructure for constructing perfect absorbers. Herein, we report a direct self-organization growth of ultrathin (similar to 130 nm) multi-scale Ag nanostructures in SiO2 matrix on quartz or plastic substrates via sputtering. Based on the elaborate microstructure design, the cavity-mode excitation, local plasmon resonances and their lightning-rod effects are synergistically activated, yielding a near constant absorptance of over 95% across the 30 0-170 0 nm wavelength even with some reflectance loss from the quartz surface and more than 98% visible absorptance with a simple antireflection treatment. Further, due to the enclosed nanostructures, the wide-angle absorbers present outstanding light-to-heat capability and thermal robustness under concentrated solar illumination. The simple material recipe (Ag, SiO2) and fabrication scheme suggest that our approach is with easy scalability. We anticipate that the proposed concept in this study can facilitate the rapid development of highly efficient ultrathin perfect absorbers. (c) 2021 Elsevier Ltd. All rights reserved.

SmCo高温永磁体的磁性能与其特有的胞状组织结构密切相关,等温时效过程是胞状组织结构形成的主要阶段.采用透射电子显微镜(TEM)对2:17型SmCo合金等温时效过程中的物相结构进行了表征,阐述了胞状组织结构的TEM测试方法.结果表明,通过特定晶带轴的选取,借助选区电子衍射和暗场像,可以对固溶体中的纳米尺度短程有序化微区和时效初期的胞状组织结构胚芽进行精确表征.结合高分辨分析,可以进一步对2:17R相的有序化转变和胞状组织结构的生长进行分析,并证明时效保温阶段结束时已形成1:5H、2:17R、1:3R三相共存的胞状组织结构.

To validate the radio frequency (RF) compatibility between the different RF units and every satellite sub-system, the electromagnetic compatibility (EMC) test of SVOM satellite was performed on the qualified model (QM). The objectives, configuration and procedures of EMC test are described in detailed. The test results showed the correctness and effectiveness of the EMC design.

The SVOM (Space-based multi-band astronomical Variable Objects Monitor) is an international cooperation project lead by CNSA (Chinese National Space Agency) and CNES(Centre National d'Etudes Spatiales, France), which focuses on the detection of GRB (Gamma-Ray Burst). X-band system is the data transmission channel for SVOM science data. In corporation with both the Chinese and French x-band ground stations, on board x-band system sends the science data of different payloads to the scientists according to the arrangement of downloading plan. In this paper, on board x-band system design and board to ground interface is elaborated. The validation and measurement of the board to ground interface proves the effectiveness of on board system design.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.