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Simulation and experimental studies are carried out on single‐layer and double‐layer embedded metal meshes (SLEMM and DLEMM) to assess their performance as transparent electromagnetic interference (EMI) shielding. The structures consist of silver meshes embedded in polyethylene terephthalate (PET). As a transparent electrode, SLEMMs exhibit a transparency of 82.7% and a sheet resistance of 0.61 Ωsq⁻¹as well as 91.0% and 1.49 Ωsq⁻¹. This performance corresponds to figures of merit of 3101 and 2620, respectively. The SLEMMs achieve 48.0 dB EMI shielding efficiency (SE) in the frequency range of 8–18 GHz (X‐ and Ku‐bands) with 91% visible transmission and 56.2 dB EMI SE with 82.7% visible transmission. Samples exhibit stable performance after 1000 bending cycles with a radius of curvature of 4 mm and 60 tape test cycles. DLEMMs consist of fabricating SLEMM on opposite sides of the substrate where the distance can be varied using a spacer. Simulations are performed to investigate how varying spacer distance between two layers of metal meshes influences the EMI SE. DLEMMs are fabricated and achieved an EMI SE of 77.7 dB with 81.7% visible transmission. SLEMMs and DLEMMs may have a wide variety of applications in aerospace, medical, and military applications.

 

In this study, a machine learning based computational approach has been developed to investigate the cation distribution in spinel crystals. The computational approach integrates the construction of datasets consisting of the energies calculated from density functional theory, the training of machine learning models to derive the relationship between system energy and structural features, and atomistic Monte Carlo simulations to sample the thermodynamic equilibrium structures of spinel crystals. It is found that the support vector machine model yields excellent performance in energy predictions based on spinel crystal structures. Furthermore, the developed computational approach has been applied to predict the cation distribution in single spinel MgAl2O4 and MgFe2O4 and double spinel MgAl2-aFeaO4. Agreeing with the available experimental data, the computational approach correctly predicts that the equilibrium degree of inversion of MgAl2O4 increases with temperature, whereas the degree of inversion of MgFe2O4 decreases with temperature. Additionally, it is predicted that the equilibrium occupancy of Mg cations at the tetrahedral and octahedral sites in MgAl2-aFeaO4 could be tuned as a function of chemical composition. Therefore, this study presents a reliable computational approach that can be extended to study the variation of cation distribution with processing temperature and chemical composition in a wide range of complex multi-cation spinel oxides with numerous applications.

 

The infrared (IR) gas sensing technique is excellent for CO 2 gas detection systems that require high accuracy and safety standard; however, there is a significant barrier to its application due to its high cost and difficulty in miniaturization. CO 2 sensors that are functional within near- or short-wavelength IR have the potential to reduce this barrier. In this work, a highly sensitive plasmonic material based on nanostructured covellite copper sulfide (CuS), which exhibits desired localized surface plasmon resonance for surface-enhanced IR absorption (SEIRA) throughout near- and mid-IR ranges, was investigated. We prepared CuS thin films facilely in an additive manner based on a spatial successive ionic layer adsorption and reaction process at room temperature. The resulting CuS thin film possesses a structure consisting of hexagonal nanoflakes, and demonstrates significant SEIRA for 100 ppm CO 2 with an enhancement factor of 10 4 . 

Nanostructured gold has attracted significant interest from materials science, chemistry, optics and photonics, and biology due to their extraordinary potential for manipulating visible and near‐infrared light through the excitation of plasmon resonances. However, gold nanostructures are rarely measured experimentally in their plasmonic properties and hardly used for high‐temperature applications because of the inherent instability in mass and shape due to the high surface energy at elevated temperatures. In this work, the first direct observation of thermally excited surface plasmons in gold nanorods at 1100 K is demonstrated. By coupling with an optical fiber in the near‐field, the thermally excited surface plasmons from gold nanorods can be converted into the propagating modes in the optical fiber and experimentally characterized in a remote manner. This fiber‐coupled technique can effectively characterize the near‐field thermoplasmonic emission from gold nanorods. A direct simulation scheme is also developed to quantitively understand the thermal emission from the array of gold nanorods. The experimental work in conjunction with the direct simulation results paves the way of using gold nanostructures as high‐temperature plasmonic nanomaterials, which has important implications in thermal energy conversion, thermal emission control, and chemical sensing.

 

Metal nanomeshes are demonstrated as flexible transparent conductors with performance comparable to indium tin oxide. However, it is not known what the performance limits of these structures are in terms of transparency and sheet resistance. More importantly, the haze, which describes how much incident light is scattered by these structures, has not been studied. In this paper, the transmission, sheet resistance, and haze of metal nanomeshes are comprehensively studied to determine their fundamental performance limits as transparent conductors through simulations and experiments. Numerical simulations and analytical calculations are used to evaluate the tradeoffs and correlations between these three figures of merit. A strong correlation is found between haze and transmission, where structures with high transmission tend to have low haze and vice versa. Structures with a pitch above 1000 nm are beneficial for achieving transmission over 80% and larger thickness is favorable in reducing sheet resistance without significantly affecting transmission. Furthermore, metal nanomeshes are fabricated to verify simulation results. The haze may be primarily explained by Fraunhofer diffraction, but the spectral dependence of haze requires analysis with Mie scattering theory. The results should apply to all metal grid or grating‐like structures. The fundamental performance limits evaluated here are helpful for guiding engineering design and research prioritization.