Shield Window Research Articles

The enhancement in microstructure, optical and electromagnetic shielding properties of Al-doped Ag thin films by annealing treatment

Ag thin films having attractive optical transmittance and effective shielding capability are usually used as a preferred choice for the transparent electromagnetic shielding windows. Whereas, the Ag films are grown primarily via an island growth (Volmer-Weber) mechanism, which greatly restricts its application. In this study, by introducing Al atoms and suitable annealing treatment, the continuous and smooth Ag thin films are successfully fabricated by magnetron co-sputtering method. The effect of annealing temperature on the microstructure, optical and electromagnetic shielding properties of the films are conducted the comprehensive and profound study. Our results indicate that the 5 mol% Al-Ag thin film annealed at 200 °C could transform into planar growth structure, and display excellent the highest optical transmittance 89.15 % at 550 nm. Meanwhile, the shielding effectiveness (SE) reaches a peak value of 28.1 dB. 500 °C is estimated as the threshold annealing temperature of Al-Ag thin film with comprehensive performances gradually declining. Moreover, the Al dopants significantly improve the thermal stability of Ag thin films than that of the pure Ag films. These findings are of important guidance for the preparation of high-quality Al-Ag thin films to meet the practical applications.

New lead-free chemistry for in-situ monitoring of advanced nuclear power plant

Nuclear power is essential for sustainable energy infrastructure and economic development, necessitating materials for high-radiation environments that can facilitate visualization and observation. Conventional lead glass is inadequate for future requirements due to radiation-induced darkening, poor mechanical properties, and toxicity. Therefore, there is urgent to find new window materials that offer multi-ionization shielding (particularly against deep-penetrating gamma ray, γ, and neutron, n, radiations), desirable opto-mechanical properties, service stability against darkening, and non-toxicity. In this study, we report a family of transparent rare-earth pyrochlore ceramics LaxGd2−xZr2O7, offering unique chemo-physical properties that are ideal for robust radiation shielding windows. Remarkably, we demonstrated the capability of maintaining high transparency under heavy-dose exposure to 1000 ​kGy 60Co γ radiation. We observed the service stability against radiation darkening can be greatly enhanced with La-rich compositions, while Gd-rich compositions undergo shallow darkening that can be reversibly recovered under visible light. This behavior is attributed to mitigated oxygen migration from 48f to 8a in La-rich compositions, which have high pyrochlore phase stability and well-ordered atomic structures, and reversible oxygen migration between 48f and 8a in Gd-rich compositions, which remain active at room temperature. Our proposal and demonstration unlock ample opportunities in designing functional transparent ceramics as window materials for demanding applications in high-radiation environments.

Exploring structural and optical properties of Cu-doped and Fe-doped sodium borate glasses

This study investigated the structural and optical properties of Cu-doped and Fe-doped sodium borate glasses. X-ray diffraction (XRD) patterns confirmed that both samples were amorphous, with no sharp peaks. However, differences in the width and center of the high-intensity humps suggested variations in atomic packing and field strength between the two samples. Fourier transform infrared (FTIR) spectra showed wider vibrational modes and stronger absorption in the Fe-doped sample, confirming its higher atomic packing and field strength. Luminescence spectra indicated that the Cu-doped sample had a higher ratio of Cu2+:Cu3+ than the Fe-doped sample of Fe2+:Fe3+, resulting in greater UV–visible region absorption. Optical parameters such as absorbance, transmittance, and reflectance supported these findings, with the Fe-doped sample exhibiting higher absorbance band edges. Quality factor (Q.F.) analysis revealed that the Fe-doped sample had a larger Q.F. than the Cu-doped sample, indicating lower energy losses. Furthermore, the optical conductivity of both samples increased with photon energy, with the Cu-doped sample dominating in all energy regions. Finally, both samples exhibited high effective atomic numbers, suggesting potential applications in radiation shielding, with the Cu-doped sample having a wider radiation shielding window. Finally, the findings unique structural and optical properties suggests the Cu-doped and Fe-doped sodium borate glasses to a lot of potential applications in various fields including radiation shielding, optics, electronics, and energy storage.

Absorptive metasurface with optical transparency for broadband RCS reduction.

Here, we introduce an optically transparent and flexible metasurface designed for effective absorption within the microwave spectrum. Indium tin oxide (ITO) films with varying square resistances fabricate a metasurface ground layer and a lossy pattern layers. Polydimethylsiloxane (PDMS) with a low refractive index, high transparency, and high flexibility is chosen as the dielectric layer. The proposed structure exhibits a reflection band of less than -10 dB with a fractional bandwidth of 167% in the range of 3.0-33.8 GHz under vertical incident electromagnetic waves. The metasurface designed based on this unit allows for the attainment of a radar cross section (RCS) reduction bandwidth of 8.75-31.1 GHz with a 10 dB reduction and a fractional bandwidth of 112%. The metasurface can maintain a broadband RCS reduction over a range of 45° incidence angles. In addition, due to the flexibility of the structure, we analyzed its RCS reduction capability when non-planar by wrapping the structure around a cylinder. The integration of simulation and testing has demonstrated that the structure exhibits excellent performance in the field of electromagnetic stealth. It has potential practical applications in electromagnetic shielding windows and the windows or domes of airplanes or satellites.

Developing novel high-lead equivalence transparent ceramic windows for effective γ-ray shielding

In response to the limitations of current transparent window materials in γ-ray shielding scenarios, herein, high-lead equivalent (0.865 mmpb) Yb2Hf2O7 transparent ceramics (YbHO-TCs) were prepared via a solid-state reaction and vacuum sintering. The fabricated YbHO-TC shows high transparency, where the in-line transmittance up to 78.9 % at 1200 nm, which is extremely close to their theoretical limit (79 %). Additionally, the linear absorption coefficient of YbHO-TC for γ-rays is 0.482, approximately twice that of the state-of-the-art lead glass materials widely employed in radiation-shielding windows. Remarkably, YbHO-TC displayed no discoloration, and its in-line transmittance exhibited little change even when exposed to a radiation dose as high as 800 kGy. The innovative developed YbHO-TC integrates high transparency and high-lead equivalent properties, not only rending them highly promising for deployment as γ-rays shielding windows but also inspiring the controllable design of high-performance optical windows tailored for use in radiation shielding applications.

Smart windows with adjustable electromagnetic interference shielding using hydrogel technology

Thermochromic smart windows with adjustable electromagnetic interference (EMI) shielding capability are integral elements in modernized buildings, especially in military applications, due to their energy-saving benefits and ability to mitigate electromagnetic pollution. However, its application is limited by the relatively poor light transmission of conductive substances and the high demand for light transmission of thermochromic smart windows. Maintaining the thermochromic performance of smart windows while adjusting EMI shielding effectiveness (SE) poses a significant challenge. Here, we propose a straightforward approach to create a smart EMI shielding material with adaptable properties, including light transmission, shape, and EMI SE. This method involves a layer-by-layer polymerisation process followed by solvent substitution. The resulting hydrogel exhibits tunable optical properties, making it suitable for use as a smart window that responds to external conditions and offers local tunability. Noteworthy characteristics include high light transmittance (80.87 %), ultra-fast response time (16 s), multiple shape adjustments, adjustable EMI SE ranging from 0 to 27.64 dB, and strong adhesion, among other features. These findings suggest that the obtained hydrogels have significant potential to provide a substantial advantage in developing next-generation soft and intelligent smart EMI shielding windows.

Transmittance enhancement and unique optical absorption of Yb2Hf2O7 ceramics via air annealing

Highly transparent Yb2Hf2O7 (YbHO) transparent ceramics hold promise as radiation shielding windows and luminescent host materials, and vacuum sintering is an effective way to fabricate highly dense YbHO ceramics. However, some F+ and F defect centers and some Yb2+ ions will be generated during vacuum sintering of YbHO transparent ceramics, resulting in low transparency. In response to this problem, air annealing treatment at different temperatures was adopted to eliminate defect centers of vacuum sintered YbHO ceramics and oxidize Yb2+ to Yb3+ in this work. YbHO ceramic with high in-line transmittance of 76 % at 750 nm was obtained via air annealing at 1300 °C for 4 h, which is extremely close to its limit of 79 %. Additionally, a unique optical absorption phenomenon was observed after annealing in the YbHO ceramic. The synergy effect of YbHf2++Ov+YbHf3+ in these ceramics generated from air-annealing process were proposed for the relevant reaction mechanisms involving serious optical absorption. This work is expected to provide guidance for the development of high-performance Yb-doped transparent ceramics for gamma-shielding windows and host materials.

A novel joint extraction model based on cross-attention mechanism and global pointer using context shield window

Relational triple extraction is a critical step in knowledge graph construction. Compared to pipeline-based extraction, joint extraction is gaining more attention because it can better utilize entity and relation information without causing error propagation issues. Yet, the challenge with joint extraction lies in handling overlapping triples. Existing approaches adopt sequential steps or multiple modules, which often accumulate errors and interfere with redundant data. In this study, we propose an innovative joint extraction model with cross-attention mechanism and global pointers with context shield window. Specifically, our methodology begins by inputting text data into a pre-trained RoBERTa model to generate word vector representations. Subsequently, these embeddings are passed through a modified cross-attention layer along with entity type embeddings to address missing entity type information. Next, we employ the global pointer to transform the extraction problem into a quintuple extraction problem, which skillfully solves the issue of overlapping triples. It is worth mentioning that we design a context shield window on the global pointer, which facilitates the identification of correct entities within a limited range during the entity extraction process. Finally, the capability of our model against malicious samples is improved by adding adversarial training during the training process. Demonstrating superiority over mainstream models, our approach achieves impressive results on three publicly available datasets.

Metal Mesh-Based Infrared Transparent EMI Shielding Window with Balanced Shielding Properties over a Wide Frequency Spectrum

Metal mesh films have been shown to be a promising strategy to effectively mitigate the growing issue of electromagnetic interference (EMI) in optoelectronic systems. To achieve superior shielding effectiveness, it is common to increase the thickness of the mesh film. However, mesh-based shielding materials have frequency-dependent shielding effectiveness that decreases as the frequency increases. Simply increasing the thickness of the mesh cannot effectively enhance the EMI shielding effectiveness at high frequencies. This will further lead to challenges such as increased processing difficulties and higher costs. In this paper, we present an infrared transparent electromagnetic shielding window based on metal mesh with irregular patterns and proper thickness. The mesh coating is fabricated on a sapphire substrate using ultraviolet photolithography technology and exhibits an efficient electromagnetic shielding effectiveness of more than 20 dB over the wide frequency range of 1.7–18 GHz while maintaining high infrared optical transparency. More importantly, there is no distinct variation in shielding effectiveness between low and high frequency ranges, demonstrating a balanced shielding characteristic across a broad frequency band. This work could be crucial in designing cost-effective and efficient EMI shielding windows for optoelectronic systems.

Original concept of cracked template with controlled peeling of the cells perimeter for high performance transparent EMI shielding films

The problem of sputtering of thick metal films on micro and nanotemplates is important for obtaining mesh transparent conductors with excellent optoelectric characteristics. In this work, we demonstrate for the first time the possibility of controlling the degree of peeling of the cell perimeter from the substrate for a cracked template based on egg white by alternating the operations of moistening the template with saturated water vapor and shock drying with hot air. Local peeling of the cracked template cells perimeter makes it possible to increase the thickness of the metal sputtered on the cracked template by more than 1 µm, which is not achievable for other lithographic approaches. Our technique was used to obtain thick Ag meshes with a low sheet resistance of no more than 1.59 Ω/sq and a transparency of about 89.1%. The thick Ag meshes show a shielding efficiency (SE) of 49 dB or 99.998% of the incident power of an electromagnetic wave at a frequency of 1 GHz. In a sandwich geometry, thick Ag meshes, which simulates a real shielding window, the shielding efficiency (SE) reaches 71 dB with a transparency of more than 80%.

Effects of Al-doping concentration on the structure and electromagnetic shielding properties of transparent Ag thin films

The ultra-thin Ag films with fascinating optical properties and shielding performance have broad applications in the fields of solar cells, transparent electrodes, optical spectrum filters, low-emissivity coatings, transparent electromagnetic shielding windows, etc. In this work, by introducing Al dopant, ultra-thin Ag transparent films were successfully prepared on quartz glass substrates using magnetron co-sputtering method. Effects of the Al-doping concentration on the structure, transmittance and electromagnetic shielding properties of Ag thin films were investigated in detail. It was found that a certain amount of Al can suppress the 3D island growth of Ag granules, and thus promote nucleation and continuous in plane growth. At the Al doped concentration of 5 mol%, the prepared 9 nm Al doped Ag thin films exhibited continuous, uniform and smooth surface morphology with the RMS roughness of only 0.89 nm. Meanwhile, it has good optical property with the highest transmittance value of 80.2% in the visible range and 76.8% at 550 nm. As the increase of Al concentration, the shielding effectiveness of the films goes up and then down, and the optimum concentration for maximum shielding effectiveness (SE) is about 5 mol% at which the maximum SE can reach up to 34.5 dB. These features make the Al-doped Ag thin films very useful and practical for transparent electromagnetic shielding window.

Fabry-Perot resonance-suppressed double-layer metal mesh window for electromagnetic interference shielding.

Traditional electromagnetic interference shielding windows that can simultaneously reflect microwaves and transmit visible light are usually fabricated by depositing one metal mesh layer on the surface of the window. However, such a structure always suffers from strong Fabry-Perot resonance (FPR), which leads to the decline of shielding effectiveness (SE). Here, we analyze the mechanism of FPR from a perspective of the equivalent circuit model and further report a facile approach to minimize the FPR by depositing another high-resistance mesh layer on the back side of the shielding window, which can greatly reduce reflected waves, ensuring that interference cannot be formed. Simulation results prove that FPR can be effectively eliminated by the proposed method, and experiments further show that for a shielding window made with Schott B270 glass plate, the SE can be enhanced by 6.3 dB (76.6% energy attenuation) at declining points, while transmittance is only reduced by 1.6%.

Application of Wavelet Characteristics and GMDH Neural Networks for Precise Estimation of Oil Product Types and Volume Fractions

Given that one of the most critical operations in the oil and gas industry is to instantly determine the volume and type of product passing through the pipelines, in this research, a detection system for monitoring oil pipelines is proposed. The proposed system works in such a way that the radiation from the dual-energy source which symmetrically emits radiation, was received by the NaI detector after passing through the shield window and test pipeline. In the test pipe, four petroleum products—ethylene glycol, crude oil, gasoil, and gasoline—were simulated in pairs in different volume fractions. A total of 118 simulations were performed, and their signals were categorized. Then, feature extraction operations were started to reduce the volume of data, increase accuracy, increase the learning speed of the neural network, and better interpret the data. Wavelet features were extracted from the recorded signal and used as GMDH neural network input. The signals of each test were divided into details and approximation sections and characteristics with the names STD of A3, D3, D2 and were extracted. This described structure is modelled in the Monte Carlo N Particle code (MCNP). In fact, precise estimation of oil product types and volume fractions were done using a combination of symmetrical source and asymmetrical neural network. Four GMDH neural networks were trained to estimate the volumetric ratio of each product, and the maximum RMSE was 0.63. In addition to this high accuracy, the low implementation and computational cost compared to previous detection methods are among the advantages of present investigation, which increases its application in the oil industry.

Ultrathin optically transparent electromagnetic shielding window with broadband microwave absorption and ultrahigh optical transmittance

Ultrathin optically transparent electromagnetic shielding window with broadband microwave absorption and ultrahigh optical transmittance

Structure-property correlation study of gamma irradiated BaO-PbO-K2O-B2O3-SiO2 glasses

Lead silicate glasses were prepared and characterized for radiation shielding applications. The glass composition and processing parameters were optimised to obtain a transparent glass with required density, optical and shielding properties. The glass plates were exposed to 30 kGy of Co-60 gamma dose. Linear attenuation coefficient measured experimentally in pre- and post-gamma irradiated samples found to be almost unchanged, validating them as good shielding materials. The glasses turned brown after irradiation due to the formation of colour centres. Radiation induced absorption decreased with the addition of Ceria in the glass composition and the transparency was recovered after annealing at 300 °C temperature. Raman spectra were analyzed to derive the structural information. There was a trend of increase in non-bridging oxygen post irradiation resulting a decrease in transition temperature (Tg) and micro-hardness. Raman spectra further showed increase in D1 and D2 peaks corresponding to 3 and 4 member -Si-O-Si- ring structures. Owing to 3 or 4 member rings being more closed pack than usual 6 member rings, this leads to increase in refractive index of glasses post irradiation. Positron annihilation lifetime spectroscopy (PALS) measured an increase in voids/ free volumes in post-irradiated glass. Investigations of the properties post gamma irradiation helped us to better understand the potentials of BaO-PbO-K2O-B2O3-SiO2 glasses as radiation shielding windows.

Transparent Saltwater in Glass Structure: Simultaneous Tunable UHF Antenna and EMI Shielding Window

Transparent Saltwater in Glass Structure: Simultaneous Tunable UHF Antenna and EMI Shielding Window

Optically transparent and very thin structure against electromagnetic pulse (EMP) using metal mesh and saltwater for shielding windows

An electromagnetic pulse (EMP) with high energy can damage electronic equipment instantly within a wide range of thousands of kilometers. Generally, a metal plate placed inside a thick concrete wall is used against an EMP, but it is not suitable for an EMP shielding window, which requires not only strong shielding effectiveness (SE) but also optical transparency (OT). In this paper, we propose a very thin and optically transparent structure with excellent SE for EMP shielding window application. The proposed structure consists of a saltwater layer held between two glass substrates and two metal mesh layers on the outside of the glass, with a total thickness of less than 1.5 cm. The SE and OT of the structure are above 80 dB and 45%, respectively, which not only meet the requirement of EMP shielding for military purposes but also retain the procedure of good observation. Moreover, the OT of the structure can be significantly improved using only one metal mesh film (MMF) layer, while the SE is still maintained high to satisfy the required SE for home applicants. With the major advantages of low cost, optical transparency, strong SE, and flexible performance, the proposed structure can be considered a good solution for transparent EMP shielding windows.

Experimental investigation on the movement mechanism of top coal in steeply inclined ultra-thick coal seams

The pre-blasting zones have a significant influence on the coal broken and the recovery rate of the top coal caving mining. This paper explores the coal movement mechanism in the top coal with pre-blasting zones based on the geological parameters of Jiangcang No. 1 mine in the western of China. The steeply inclined ultra-thick coal seam was mined by using the sublevel top-coal caving mining method. The geo-image process system (GIPS) software was used to track the mark points on the coal and roof. The support was used to record the load on the top of the support during the caving mining process. The results show that the horizontal coal is moved to the shield window and the vertical coal is moved downward in the first level, while that in the second level shows consistency for the integrity of the coal. The vertical displacements of the corresponding points in the first level are lairger than that in the second level. However, the load on the top of the support in the first level is smaller than that in the second level. It indicated that the pre-blasting zones will give a more loosen top-coal and a small degree of difficulty in the top coal caving. The steeply inclined ultra-thick coal seam was divided into three levels in horizontal direction (presenting 25 m in the real sublevel height of top coal) for each level. The technical tunnel was set at the bottom of the first level in the coal. Two rows pre-blasting zones were set with different dip angles and lengths from the technical tunnel to the coal with a proportional distance. The second level without pre-blasting zones was introduced to compare with the first level with pre-blasting zones during the caving process.

Plasma treatment to tailor growth and photoelectric performance of plasma-enhanced atomic layer deposition SnOx infrared transparent conductive thin films

The performance of atomic layer deposition films is mainly limited by precursor residues, low crystallinity and densities due to low deposition temperatures. Here, we used atomic layer deposition to deposit tin oxide thin films at a relatively low temperature of 250 °C. At this temperature, the change in the valence of Sn due to precursor residue is eliminated by layer-by-layer Ar plasma treatment, and the crystallinity of the films is improved. The effects of Ar plasma treatment power and Ar treatment time on the structural and optoelectronic properties were investigated. It was found that Ar plasma treatment time more significantly affects the surface morphology and the optical and electrical properties of the film. The film is transparent to both visible and near-infrared light over a wide range of wavelengths from 400 nm to at least 5000 nm. The film resistivity can be as low as 1.117 × 10−3 Ω·cm. The film has a relatively low level of residual stress due to the fact that there is no need to improve the crystallinity of the film by conventional high temperature annealing. On the basis of the high transparency and high conductivity of the SnOx films with layer by layer Ar plasma treatment in situ, the films can be applied as electromagnetic shielding windows for photodetectors.

The Micro-Miniature Capacitance Sensor Based on Light-Trigger Technology and Its Hardware Design in the Electrical Capacitance Tomography System

Electrical capacitance tomography (ECT) technology can monitor the multi-phase flow in closed pipes or vessels. The monitoring technology has the advantages of anti-intrusion, low manufacturing cost, high-temperature resistance, and simple structure. At present, ECT systems use small-scale sensors for signal capture, but such sensors have problems such as low sensitivity and poor anti-interference, which have attracted the attention of researchers. In this study, a light-trigger sensor was proposed, which was equipped with a special light window to receive optical signals. At the same time, in terms of the problem of electromagnetic shielding and optical window protection, a light window structure that transmitted optical signals and shields electromagnetic waves was designed. Based on the light-trigger sensor, the other modules of the ECT system were designed, considering that the sensor would be interfered by the measurement of stray capacitance, the intra-isoelectric driver cable shielding technology, the double T-type simulation switch matrix, and the digital-mode demodulation technology was introduced. Consequently, the performance of the sensor was tested. During the experiment, the sucrose flow pattern was used as the test object. The results showed that compared with the traditional sensors, the image distortion of the sensor based on the ECT system was lower; while in the performance test of the ECT system, the introduction of the double T-type simulation switch matrix, the digital-analogy demodulation technology, and the bipolar plate excitation mode could further optimize the signal-to-noise ratio index of the image; in the sensitivity test of the ECT system, the introduction of bipolar plate excitation mode could improve the output sensitivity of the capacitance.