Multilayer Structure Research Articles

Mechanical Properties and High-Temperature Steam Oxidation of Cr/CrN Multi-Layers Produced by High-Power Impulse Magnetron Sputtering

In this study, Cr coatings, CrN coatings, and CrN/Cr multi-layer coatings were deposited on the surface of Zr-4 alloy by high-power impulse magnetron sputtering (HiPIMS). We have investigated the effect of coating structure on the microstructure, mechanical properties, and high-temperature steam oxidation properties of coatings. The results show that the single-layer CrN coating has higher hardness but performs poorly in high-temperature steam oxidation compared to the Cr coating due to its greater brittleness, which makes it prone to cracking and spalling in high-temperature steam environments and provides a channel for Zr diffusion. In multi-layer coatings, however, they form a fine columnar crystal structure and a smoother surface, and the more layers there are, the better the mechanical properties and resistance to high-temperature steam oxidation of the coating. In a high-temperature steam environment, the CrN layer decomposes to form Cr2N and N2, and the N atoms diffuse inwards and react with Zr to form an α-Zr(N) layer, which restricts interdiffusion between Cr and Zr and blocks the diffusion of O into the substrate. Therefore, (CrN/Cr)n coatings with a multi-layer structure have excellent high-temperature steam corrosion resistance.

Tunable Group Delay of Reflected Beam in Multilayered Structures with Antisymmetric Graphene via Magnetic Control

In this paper, we demonstrate the magnetic field-adjustable group delay of the reflected beam in the terahertz frequency range, using a multilayer architecture incorporating three layers of antisymmetric graphene. The observed enhancement in group delay results from localized field amplification, which occurs due to the excitation of surface plasmon polaritons on the graphene at the interface between two dielectric layers. By considering the quantum mechanical response of graphene, the polarity of the group delay can be reversed by exploiting the antisymmetric conductivity characteristics of graphene. Furthermore, the group delay can be dynamically modulated either by varying the external magnetic field or by adjusting the structural parameters. The achieved enhancement and tunability of the group delay offer significant potential for the development of graphene-based terahertz modulation devices and other optical delay applications.

A generalized V-shaped peeling model on rigid curved substrates incorporating pre-stretch effects

Abstract In biological adhesion systems, it is often observed that organisms climb on curved surfaces by controlling the relaxation and contraction of their muscles. In this paper, we propose a general model for V-peeling on an arc-shaped substrate based on Griffith's energy release theory. The developed model can handle V-peeling problems on arc-shaped substrates with arbitrary initial configurations and considers the effects of pre-stretching in the bonded segment. When the substrate radius and initial peeling angle are relatively large, the results approach those obtained for flat substrates. However, due to the constraints of the substrate size and its active alteration of the peeling angle, a steady state, as seen on flat substrates, does not occur during the peeling process. Pre-stress has a certain inhibitory effect on the initiation of delamination, but once delamination begins, the presence of pre-stress promotes it. Meanwhile, same degree of pre-stretch has a more pronounced effect on enhancing the peel resistance of structures with smaller curvatures, and pre-stretch further amplifies the differences between arc-shaped and flat substrates. The paper also discusses the impact of variations in different parameters on energy. The conclusions drawn in this study have implications for understanding biological adhesion and designing multilayered structures.

A Study of Temperature and Humidity Conditions in a New Energy-Efficient Design of a Wall Structure with Air Gaps

This manuscript presents a theoretical study of a newly developed energy-efficient external wall structure in comparison with a traditional ventilated facade. To conduct numerical studies based on mathematical models of the heat transfer of water vapor filtration through a multilayer filler structure with ventilated and non-ventilated air gaps, a calculation method was developed that additionally considers the presence of heat-reflecting screens and different variations in the geometric parameters of air gaps and thermal insulation layers. The study results demonstrated that the new energy-efficient multilayer wall structure was 6.1–7.2% more efficient in terms of heat transfer resistance than the traditional one, and due to the presence of heat-reflecting screens, the efficiency increased to 15.2–16.3% depending on the geometric parameters of the air and thermal insulation layers of the wall structure. In addition, in all the considered variants of the filler structure geometry (i.e., with closed and ventilated air gaps), there were water vapor condensation zones, but it was established that according to the value of the inadmissibility of moisture accumulation in multilayer wall structures, over the annual period of operation, the structures complied with the standard climatic conditions of Shymkent. The results of this study thus positively complement the existing catalog of energy-efficient wall structures, and the new wall structure can be used while considering the necessary geometric parameters of air and heat-insulating layers when designing buildings in the corresponding climatic conditions.

Light matters: fabrication and investigation of optical and wetting properties of TiO2/SiO2 multilayer structure

Light matters: fabrication and investigation of optical and wetting properties of TiO2/SiO2 multilayer structure

Performance analysis of metallo-dielectric optical filters designed using dispersion relations

We present an experimental validation of an analytical approach to predict the spectral response of multilayer metallo-dielectric structures, with applications in the efficient design of bandpass optical filters. Instead of relying on trial-and-error methods, our approach—referred to as the dispersion relation method—is based on intrinsic physical relations, potentially resulting in a significant reduction in time and resources during the design and optimization process. In our previous work, we illustrated that characteristics of the band structure revealed by the dispersion relation can serve as reasonable estimates for the center wavelengths and bandwidths for finite multilayer structures, as obtained from numerical simulations. In this work, we verify those conclusions with experimental results from metallo-dielectric optical filters prepared via magnetron sputtering. Structures using different metals including Ag, Au, and Al are investigated. We show good agreement between spectral response predictions derived from dispersion relations, numerical simulations using the transfer matrix method, and experimental transmittance spectra of the fabricated structures. Considering this experimental validation, the analytical approach based on dispersion relations can offer an accurate and efficient method for designing metallo-dielectric filter structures. Our approach facilitates the selection of geometric parameters for fabrication and provides valuable insight into the optical characteristics of such structures.

Advancements in Free-Standing Ferroelectric Films: Paving the Way for Transparent Flexible Electronics

Free-standing ferroelectric films have emerged as a transformative technology in the field of flexible electronics, offering unique properties that enable a wide range of applications, including sensors, actuators, and energy harvesting devices. This review paper explores recent advancements in the fabrication, characterization, and application of free-standing ferroelectric films, highlighting innovative techniques such as multilayer structures and van der Waals epitaxy that enhance their performance while maintaining mechanical flexibility. We discuss the critical role of these films in next-generation devices, emphasizing their potential for integration into multifunctional systems that combine energy harvesting and sensing capabilities. Additionally, we address challenges related to leakage currents, polarization stability, and scalability that must be overcome to facilitate commercialization. By synthesizing current research findings and identifying future directions, this paper aims to provide a comprehensive overview of the state-of-the-art in free-standing ferroelectric films and their impact on the development of sustainable and efficient flexible electronic technologies.

Strategic enhancement of joint strength in dissimilar Al/Mg alloys: a workable approach for aerospace application

The increasing importance of dissimilar lightweight metal joints is crucial for advancing aerospace and automotive technologies, where aluminum (Al) and magnesium (Mg) alloys offer an ideal balance of strength and weight. However, the challenges associated with joining these dissimilar metals necessitate innovative solutions. This study explores the role of silicon carbide (SiC) nanoparticles in enhancing the friction stir spot welding (FSSW) of dissimilar alloys AA6061 and AZ31B. The methodology involved varying the rotational speed of the welding tool (1000, 1200, 1400, and 1600 rpm) while keeping other parameters such as plunge depth, plunge rate, and dwell time constant. SiC nanoparticles were introduced through a pre-drilled 2 mm hole at the tool’s plunging point to refine the microstructure and mitigate the formation of brittle Al–Mg intermetallic compounds (IMCs). The addition of SiC nanoparticles modifies the weld microstructure, reducing the formation of brittle Al–Mg IMCs and promoting the development of finer, well-distributed Mg–SiC IMCs, resulting in a more favorable and homogeneous multilayered structure. The incorporation of SiC significantly enhances the strength of the joints, achieving a maximum of 5.68 kN, 22.7% increase compared to SiC-free Al/Mg joints. This improvement underscores potentiality of SiC as a reinforcing element in strengthening dissimilar metal joints and demonstrates the effectiveness of it in dissimilar Al/Mg joints, making them suitable for aerospace and automotive applications.

Infrared photoresponse of GeSiSn p–i–n photodiodes based on quantum dots, quantum wells, pseudomorphic and relaxed layers

Structural and photoelectric properties of p-i-n photodiodes based on GeSiSn/Si multiple quantum dots (QDs) both on Si and silicon-on-insulator substrates were investigated. Elastic strained state of grown films was demonstrated by x-ray diffractometry. Annealing of p-i-n structures before the mesa fabrication can improve the ideality factor of current-voltage characteristics. The lowest dark current density of p-i-n photodiodes based on QDs at the reverse bias of 1 V reaches the value of 0.8 mA cm-2. The cutoff wavelength shifts to the long-wavelength region with the Sn content increase. Maximum cutoff wavelength value is found to be 2.6μm. Moreover, multilayer periodic structures with GeSiSn/Ge quantum wells and GeSiSn relaxed layers on Ge substrates were obtained. Reciprocal space maps were used to study the strained state of GeSiSn layers. The optimal growth parameters were determined to obtain slightly relaxed GeSiSn layers. Designed p-i-n photodiodes based on these structures demonstrated the minimal dark current density of 0.7 mA cm-2and the cutoff wavelength of about 2μm.

Application and progress of 3D printed biomaterials in osteoporosis

Osteoporosis results from a disruption in skeletal homeostasis caused by an imbalance between bone resorption and bone formation. Conventional treatments, such as pharmaceutical drugs and hormone replacement therapy, often yield suboptimal results and are frequently associated with side effects. Recently, biomaterial-based approaches have gained attention as promising alternatives for managing osteoporosis. This review summarizes the current advancements in 3D-printed biomaterials designed for osteoporosis treatment. The benefits of biomaterial-based approaches compared to traditional systemic drug therapies are discussed. These 3D-printed materials can be broadly categorized based on their functionalities, including promoting osteogenesis, reducing inflammation, exhibiting antioxidant properties, and inhibiting osteoclast activity. 3D printing has the advantages of speed, precision, personalization, etc. It is able to satisfy the requirements of irregular geometry, differentiated composition, and multilayered structure of articular osteochondral scaffolds with boundary layer structure. The limitations of existing biomaterials are critically analyzed and future directions for biomaterial-based therapies are considered.

Energy efficiency analysis of spin–orbit torque MRAM using composition dependent resistivity and spin Hall angle in Pt/W multilayer structure

Current-induced magnetization switching through spin–orbit torque (SOT) enables low-energy and high-speed switching of magnetic memory (MRAM), positioning SOT-MRAM as a promising candidate for next-generation memory technology. As energy consumption in data computation has become a major challenge in the 21st century, significant efforts have been dedicated to developing energy-efficient memory devices. To optimize SOT-MRAM for energy efficiency, achieving a high spin Hall angle (SHA) has been regarded as essential, as a high SHA indicates efficient spin current generation. However, while previous studies have focused on increasing SHA, this has often led to increased resistivity, which may hinder overall energy efficiency in SOT-MRAM. We propose that resistivity is almost as important as SHA in determining the energy efficiency of SOT-MRAM. In this study, we analyze the effects of both SHA and resistivity in SOT channel materials, which can be modulated by adjusting the composition of Pt and W in Pt/W multilayers. We observed that varying the Pt and W compositions resulted in non-linear changes in both SHA and resistivity, suggesting that evaluating energy efficiency based solely on SHA may be misleading. Thus, we introduce a figure of merit, ξ=ρθSH2, which represents the combined impact of SHA and resistivity on SOT-MRAM energy efficiency. We hope that our findings reveal the importance of considering both SHA and resistivity in the development of energy-efficient SOT-MRAM.

Symbolic Narratives in Graphic Design: Semiotic Perspectives on Advertising Visuals

This study examines how consumer culture is reproduced through advertising visuals in the context of graphic design. Three different advertisements were selected, and the graphic design elements used in these visuals (such as color, composition, and symbols) were analyzed in terms of their impact on consumer perception. Employing the semiotic analysis method, the study reveals that advertising visuals are not merely aesthetic tools but also carriers of ideological and social meanings. The findings indicate that graphic design elements effectively convey the ideological messages of consumer culture and establish profound symbolic connections between brands and consumers. Additionally, the role of graphic design has become more prominent in the digital era, evolving into an interactive and multi-layered structure within modern consumer culture. This study underscores the critical function of graphic design as a communication tool that not only creates visual aesthetics but also shapes social values and consumer behaviors. In conclusion, advertising visuals are evaluated as strategic tools in the reproduction of consumer culture, contributing to theoretical and applied studies in this field.

Interfacial modification in multilayered charge generation layer structure for highly efficient charge generation in tandem OLEDs

Interfacial modification in multilayered charge generation layer structure for highly efficient charge generation in tandem OLEDs

Effect of projectile nose shape on ballistic resistance of multi-layered explosively welded plates

In the present study, the ballistic perforation resistance of steel/titanium/aluminum (STA) multilayer protective systems impacted by spherical, ogival, conical, and blunt projectiles was investigated experimentally, numerically, and analytically. The targets were manufactured via explosive welding technique to achieve a strong interfacial strength. The projectile nose shape was found to significantly affect the failure modes and ballistic limit velocities of the STA composite plate. Detailed three-dimensional finite element simulations were performed to provide insights into the penetration process and energy absorption characteristics of the STA composite plate. An analytical model was developed to predict the entry and exit penetration phases of a rigid projectile of different nose shapes into the STA target through ductile hole expansion. The model simplified the STA composite plate to be an equivalent monolithic based on the weighting of material resistance and specific cavitation energy in each layer. The analytical and numerical predictions of the residual velocity were in excellent agreement with the experimental data. The predicted evolution of projectile velocity with penetration depth was found to be in satisfactory correlation with those from the numerical simulation. The proposed analytical model shall be useful for designers of multilayer metallic protective structures against fragments from improvised explosive devices.

Multilayer temperature inversion structures and their potential impact on atmospheric pollution in northwest China

Multilayer temperature inversion structures and their potential impact on atmospheric pollution in northwest China

Ultra-broadband absorber and near-perfect thermal emitter based on multi-layered grating structure design

Ultra-broadband absorber and near-perfect thermal emitter based on multi-layered grating structure design

Layer-by-Layer Nanoarchitectonics: A Method for Everything in Layered Structures

The development of functional materials and the use of nanotechnology are ongoing projects. These fields are closely linked, but there is a need to combine them more actively. Nanoarchitectonics, a concept that comes after nanotechnology, is ready to do this. Among the related research efforts, research into creating functional materials through the formation of thin layers on surfaces, molecular membranes, and multilayer structures of these materials have a lot of implications. Layered structures are especially important as a key part of nanoarchitectonics. The diversity of the components and materials used in layer-by-layer (LbL) assemblies is a notable feature. Examples of LbL assemblies introduced in this review article include quantum dots, nanoparticles, nanocrystals, nanowires, nanotubes, g-C3N4, graphene oxide, MXene, nanosheets, zeolites, nanoporous materials, sol–gel materials, layered double hydroxides, metal–organic frameworks, covalent organic frameworks, conducting polymers, dyes, DNAs, polysaccharides, nanocelluloses, peptides, proteins, lipid bilayers, photosystems, viruses, living cells, and tissues. These examples of LbL assembly show how useful and versatile it is. Finally, this review will consider future challenges in layer-by-layer nanoarchitectonics.

A multi-layer structure β-FeOOH@GO/AgNWs membrane with robust photo-Fenton self-cleaning property for high-efficiency wastewater remediation

A multi-layer structure β-FeOOH@GO/AgNWs membrane with robust photo-Fenton self-cleaning property for high-efficiency wastewater remediation

Nonlinear Optical Bistability in a Bragg Reflector Multilayered Structure with MoS2

The special band structure of bilayer MoS2 makes it show strong nonlinear optical characteristics in the visible band, which provides a new way to develop visible nonlinear devices. In this paper, we present a theoretical analysis of the optical bistability (OB) in a silver–Bragg reflector structure by embedding bilayer MoS2 at the visible band. The nonlinear OB phenomenon is achieved due to the nonlinear conductivity of the bilayer MoS2 and the excitation of the optical Tamm state at the interface between the silver and the Bragg reflector. It is found that the hysteresis behavior and the threshold width of the OB can be effectively tuned by varying the incident light wavelength. In addition, the optical bistable behavior of the structure can be adjusted by varying the position of the MoS2 inset in the defect layer, the incident angle, and the structural parameters of the spacer layer. We believe the above results can provide a new paradigm for the construction of controllable bistable devices.

Uterine organoids reveal insights into epithelial specification and plasticity in development and disease

Understanding how epithelial cells in the female reproductive tract (FRT) differentiate is crucial for reproductive health, yet the underlying mechanisms remain poorly defined. At birth, FRT epithelium is highly malleable, allowing differentiation into various epithelial types, but the regulatory pathways guiding these early cell fate decisions are unclear. Here, we use neonatal mouse endometrial organoids and assembloid coculture models to investigate how innate cellular plasticity and external mesenchymal signals influence epithelial differentiation. Our findings demonstrate that uterine epithelium undergoes marked age-dependent changes, transitioning from a highly plastic state capable of forming both monolayered and multilayered structures to a more restricted fate as development progresses. Interestingly, parallels emerge between the developmental plasticity of neonatal uterine epithelium and pathological conditions such as endometrial cancer, where similar regulatory mechanisms may reactivate, driving abnormal epithelial differentiation and tumorigenesis. These results not only deepen our understanding of early uterine development but also offer a valuable model for studying the progression of reproductive diseases and cancers.