Journal of Materiomics最新文献

Synergistically enhancing the erosion and impact resistance of contacts poses a significant challenge for cutting-edge electrical equipment. Fortunately, mollusk shells in nature have evolved effective strategies to construct microstructures with superior erosion and impact resistance. Inspired by the structure of nacre, AgSnO₂ contact material with hierarchical architectures has been designed and fabricated. The mechanistic link between microstructural evolution and dynamic erosion is studied through experiments combined with Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) simulations. Results show that the reconstructed SnO₂ skeleton endowed with a highly continuous and anisotropic ‘flowering'-like structure forms a continuous interpenetrating network with Ag, optimizing the conductive pathways on the molten pool surface. Additionally, the Ag-rich regions in the deeper layers on both sides of the molten pool offers a stable ‘nutrient-supply’ for the continuous ‘flowering’ reconstruction of the skeleton, exhibiting excellent in-situ self-repairing erosion resistance. Benefiting from this synergistic strategy, this skeleton is reconstructed based on its natural structure, which further disperses the stress and deformation concentration while inhibiting interfacial debonding, thereby reducing the formation of cracks and significantly enhancing the impact resistance. This work is expected to breakthrough erosion and impact resistance in extreme condition electrical contact materials through biomimetic microstructure design.

A dual phase boride and carbide ceramic with the nominal composition (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)B₂ and (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C was prepared by reactive synthesis and consolidated by spark plasma sintering. The resulting microstructure contained about 30% (in volume) boride and 70% carbide. Compositional inhomogeneities were observed within single grains that had core-shell structures and preferential accumulation of specific metals in the boride or carbide phases. Specifically, Ti and Nb had higher concentrations in the boride, whereas Hf and Ta in the carbide. The Zr concentration was relatively equally distributed in the two phases. The dual phase ceramic had additional, distinctive features including nanosized inclusions, possibly related to local miscibility gaps and supersaturation, linear defects, and strain due to adjustment of the crystal structure. As a consequence, the fracture mode was transgranular with the crack path deviated by these nanometric microstructure alterations. Nanoindentation under 5 mN measured higher hardness and modulus for the boride, 30 GPa and 525 GPa, as compared to the carbide phase, 22 GPa and 425 GPa, due to a higher concentration of dislocation tangles and strains deriving from the introduction of metals with different sizes (and properties) in a less compliant hexagonal lattice.

Millimeter-wave and terahertz frequency bands are receiving more and more attention due to their big potentials for widespread applications such as in high-speed communications and high-resolution imaging. Nevertheless, limited by the functional materials and devices in these bands, we face lots of challenges towards high efficiency, high precision, and multi-domain electromagnetic manipulations that are urgently required in the practical application scenarios. The emergence of metasurfaces, especially the digital coding metasurfaces and programmable metasurfaces, has provided powerful capabilities to control electromagnetic waves. Recently, with the progress of space-domain, time-domain, space-time-domain, and polarization-domain programmable metasurfaces, considerable new applications have been achieved, including new-architecture wireless communication transmitters, the integration of sensing and communications, simultaneous information and power transfers, and information encryption. Consequently, integrated multifunctional platforms based on metasurfaces are expected. In this review, the recent advances in millimeter-wave and terahertz programmable metasurfaces are thoroughly presented, including the design principles and methods, the applications in the next-generation wireless communication systems, the integrated sensing and communications, and other multifunctional systems.

Polarization camera based on CMOS sensor and nano wire-grid technology have found widespread applications in medical diagnostics, remote sensing and industrial inspection. However, the limited filtering properties of wire-grid polarizers and the small field-of-view provided by conventional microlens restrict the energy efficiency of these systems while also increasing their cost, size and weight. In this study, we propose an innovative approach that integrates focusing and splitting of polarization states into a single-layer all-dielectric metasurface. This metasurface enables full-Stokes polarization imaging for a wide field-of-view conical light. The design of the metasurface utilizes a phase compensation method to effectively focus orthogonal polarized conical light onto the central pixel of the CMOS sensor. Theoretical analysis demonstrates that this metasurface can accurately detect full-Stokes parameters within ±20° incident cone angles with an average efficiency reaching 83.0%. The angle can be extended to ±90° with an average efficiency exceeding 80%. We fabricated a three super-pixel metasurface prototype, and experimental measurements reveal its ability to efficiently focus and split three pairs of orthogonal polarization states under ±11° conical angle incidence with an average focusing efficiency of 68.1%. This study presents a promising solution for achieving wide field-of-view and high-efficiency polarization detection in integrated CMOS systems.

In this contribution, we reply to comments made by Tkach et al. in our publication J. Materiomics 2023; 9:609. The main interest of our work is to synthesize a lead-free material, SrTi₂O₅ (STO), and then utilize it in the formation of composites and finally design the piezoelectric nanogenerator (PENG) for self-powered sensor applications. The authors have observed the presence of piezoelectric voltage and current output from the PENG. The authors humbly indicate that the PENG devices were poled using a DC poling setup as conditions mentioned in J. Materiomics 2023; 9:609 (Panda et al., 2023) [1]. The doping of STO into the PDMS increased from 2% to 20% (in mass). In this process, the piezoelectric output of the PENG device was observed to be highest for 15% (in mass) STO-PDMS composite. Besides, we agree with the comment raised by Tkach et al., and further we have addressed the issues in a step-by-step response as follows.