Surface Defects Research Articles

Machine vision system for automatic defect detection of ultrasound probes

Industry 4.0 conceptualizes the automation of processes through the introduction of technologies such as artificial intelligence and advanced robotics, resulting in a significant production improvement. Detecting defects in the production process, predicting mechanical malfunctions in the assembly line, and identifying defects of the final product are just a few examples of applications of these technologies. In this context, this work focuses on the detection of ultrasound probes’ surface defects, with a focus on Esaote S.p.A.’s production line probes. To date, this control is performed manually and therefore biased by many factors such as surface morphology, color, size of the defect, and by lighting conditions (which can cause reflections preventing detection). To overcome these shortfalls, this work proposes a fully automatic machine vision system for surface acquisition of ultrasound probes coupled with an automated defect detection system that leverage artificial intelligence. The paper addresses two crucial steps: (i) the development of the acquisition system (i.e., selection of the acquisition device, analysis of the illumination system, and design of the camera handling system); (ii) the analysis of neural network models for defect detection and classification by comparing three possible solutions (i.e., MMSD-Net, ResNet, EfficientNet). The results suggest that the developed system has the potential to be used as a defect detection tool in the production line (full image acquisition cycle takes ~ 200 s), with the best detection accuracy obtained with the EfficientNet model being 98.63% and a classification accuracy of 81.90%.

Leveraging Phenazine‐Based Ligands for Optimized Perovskite Optoelectronic Performance Through Chelation and Redox Engineering

AbstractPerovskite nanocrystals (PNCs) hold immense potential for optoelectronic and photovoltaic applications. However, their performance is hindered by surface defects that promote non‐radiative recombination and reduce stability. Surface engineering, particularly through defect passivation, is crucial for achieving high‐performing perovskite solar cells. Chelation has been shown to significantly improve the efficiency and stability of perovskite solar cells. In this study, a novel chelation strategy using 1,10‐Phenanthroline (Phen) is presented as a bidentate chelating ligand to effectively target and passivate these detrimental surface defects. By strategically designing a Phenanthroline derivative, dipyrido[3,2‐a:2′,3′‐c]phenazin‐11‐amine (Phen‐derivative) with optimized redox potentials, dual functionality: efficient defect passivation and hole transport is achieved. X‐ray photoelectron spectroscopy (XPS) confirms the superior binding capability of the Phen‐derivative due to chelation. This strong interaction facilitates efficient and ultrafast charge transfer from PNCs and the formation of a long‐lived charge‐separated state, as evidenced by sustained bleaching in transient absorption spectra. A metal‐dipyrido[3,2‐a:2′,3′‐c]phenazin‐11‐amine complex (Ir‐complex) derived from dipyrido[3,2‐a:2′,3′‐c]phenazin‐11‐amine, but lacking a chelation site, hinders desired hole transfer despite similar charge transfer energetics. This work emphasizes the critical role of chelation‐mediated interfacial interactions and energy alignment in designing effective charge shuttle molecules and unlocking the potential of lead‐chelating hole transporters for next‐generation light‐harvesting technologies.

Ball-Milling-Assisted N/O Codoping for Enhanced Sodium Storage Performance of Coconut-Shell-Derived Hard Carbon Anodes in Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are regarded as cost-effective alternatives or competitors to lithium-ion batteries for large-scale electric energy storage applications. However, their development has been hindered by the high cost of hard carbon (HC) anodes and poor electrochemical performance. To enhance the sodium storage capacity and rate performance of HC, this study accelerated the electrochemical performance of coconut-shell-derived HC anodes for SIBs through N/O codoping using ball milling and pyrolysis. Experimental results demonstrate that the simultaneous introduction of N and O generates a synergistic effect, increasing the surface oxygen-containing functional groups, defects, and interlayer spacing of coconut-shell-derived HC through the codoping of light elements. The excellent strategy has increased the slope capacity and platform capacity of HC, and the synergistic modification of N/O has increased its reversible specific capacity from 272 to 343 mA h g-1 (30 mA g-1), with a retention rate of approximately 92.1% after 100 cycles. In addition, it also exhibits an excellent rate performance, reaching 178 mA h g-1 at 1500 mA g-1. In summary, this study presents an effective strategy for modifying biomass-derived HC.

MgAc2-Modified SnO2 Electron Transport Layer for Highly Efficient and Thermal Stable Perovskite Solar Cells.

There are always defects and oxygen vacancies in SnO2 prepared by solution methods, hindering efficient carrier transfer between SnO2 and the perovskite in perovskite solar cells. Thus, we employed MgAc2 to modify the interface. Carboxyl groups of MgAc2 filled the oxygen vacancies in SnO2, reducing its surface defect density, and Mg2+ partially replaced surface Sn4+, improving the properties of the SnO2 layer. Finally, perovskite solar cells modified with MgAc2 exhibited a significant improvement in open-circuit voltage and fill factor, improving the power conversion efficiency from 20.52% to 22.02%. Moreover, MgAc2-devices maintained 80% of the initial efficiency after 1250 h in thermal stability tests at 85 °C and 30% relative humidity compared to control devices. This work provides a method for treating the SnO2 electron transport layer and demonstrates the synergistic effects of Mg2+ and acetate ions, which can facilitate the development of efficient and stable perovskite solar cells.

Efficient Energy Transfer from Quantum Dots to Closely‐Bound Dye Molecules without Spectral Overlap

Quantum dots (QDs) are semiconductor nanocrystals whose optical properties can be tuned by altering their size. By combining QDs with dyes we can make hybrid QD‐dye systems exhibiting energy transfer (ET) between QDs and dyes, which is important in sensing and lighting applications. In conventional QDs that need a shell to passivate surface defects, ET usually proceeds through Förster resonance energy transfer (FRET) that requires significant spectral overlap between QD emission and dye absorbance, as well as large oscillator strengths of those transitions. This considerably limits the choice of dyes. In contrast, perovskite QDs do not require passivating shells for bright emission, which makes ET mechanisms beyond FRET accessible. This work explores the design of a CsPbBr3 QD‐dye system to achieve efficient ET from CsPbBr3 QDs to dyes with dimethyl iminium binding groups where the close binding of dyes surface facilitates spatial wavefunction overlap. Using steady‐state and time‐resolved photoluminescence experiments, we demonstrate that efficient ET from CsPbBr3 to dyes with minimal spectral overlap proceeds via the Dexter exchange‐type mechanism, which overcomes the conventional restriction of spectral overlap that severely limits the tunability of these systems. This approach opens new avenues for QD‐molecule hybrids for a wide range of applications.

Optimized YOLOv8 based on SGW for surface defect detection of silicon wafer

Abstract Wafer detection is a critical procedure in IC manufacturing. Deep learning models are extensively used to identify the wafer defects. The key issue is how to recognize the small defects in complex backgrounds reducing the probability of misjudge and enhancing the detection accuracy. To solve the problems, we proposed a new detection model, SGW-YOLOv8 (SimAM-GhostConv-Wise IOU), based on the YOLOv8 model. The SimAM attention mechanism was added to enhance the network's focus on important positions without increase of the parameter numbers. The GhostConv improved the backbone network, and the Wise-IOU (Weighted Intersection over Union) loss function was introduced to address the deviation of evaluation results caused by the traditional loss function. Moreover, an additional detection head was appended to YOLOv8 to improve the model's capability of recognizing small targets. The dataset containing six types of defects was established by generating 6000 images of silicon wafers. The experimental results demonstrated that the mAP@0.5 of SGW-YOLOv8 increased by 4.8% compared to YOLOv8, and the model parameters are decreased by 11.8%. Therefore, the proposed SGW-YOLOv8 model is potential for wafer detection in IC industry.

Selective passivation of 2D MoS2 nanosheets surface defects by spontaneous growth of Au nanoparticles for full response-recovery NO2 detection at room temperature

Full recovery at room temperature (RT) is quite challengng for two dimensional transition metal dichalcogenides chemiresistive gas sensors. The main reason for the incomplete recovery is the strong bonding of gas molecules onto sensing layer defects. Here, we show that the recovery rate of MoS2 chemiresistive NO2 sensors can be improved by selective passivation of MoS2 nanosheets (NSs) defects with Au nanoparticles (NPs) via a simple spontaneous reduction method. MoS2 NSs were produced by liquid shear exfoliation. Pristine and Au NPs functionalized MoS2 were characterized using ς-potential, UV–Visible spectroscopy, TEM, SEM, AFM, EDS, XRD, XPS and Raman spectroscopy. The analyses confirm the presence of Au NPs on the edges of MoS2 NSs at defective sites with NP sizes of 1–4 nm and 5–30 nm. Both pristine MoS2 and Au-decorated MoS2 NSs were employed to fabricate NO2 chemiresistive devices. Au-decorated MoS2 sensors showed an improved performance (for 1 ppm NO2, Au-MoS2 sensor exhibited a response of 5.6 % instead of 2.2 % for MoS2 sensor), and gave faster response and better recovery time. Concurrently, the functionalization is independent of the adsorption and desorption of NO2. Most importantly, the functionalization of MoS2 NSs helps to full response-recovery within one hour, without either thermal or UV irradiation treatment.

Efficient Energy Transfer from Quantum Dots to Closely-Bound Dye Molecules without Spectral Overlap.

Quantum dots (QDs) are semiconductor nanocrystals whose optical properties can be tuned by altering their size. By combining QDs with dyes we can make hybrid QD-dye systems exhibiting energy transfer (ET) between QDs and dyes, which is important in sensing and lighting applications. In conventional QDs that need a shell to passivate surface defects, ET usually proceeds through Förster resonance energy transfer (FRET) that requires significant spectral overlap between QD emission and dye absorbance, as well as large oscillator strengths of those transitions. This considerably limits the choice of dyes. In contrast, perovskite QDs do not require passivating shells for bright emission, which makes ET mechanisms beyond FRET accessible. This work explores the design of a CsPbBr3 QD-dye system to achieve efficient ET from CsPbBr3 QDs to dyes with dimethyl iminium binding groups where the close binding of dyes surface facilitates spatial wavefunction overlap. Using steady-state and time-resolved photoluminescence experiments, we demonstrate that efficient ET from CsPbBr3 to dyes with minimal spectral overlap proceeds via the Dexter exchange-type mechanism, which overcomes the conventional restriction of spectral overlap that severely limits the tunability of these systems. This approach opens new avenues for QD-molecule hybrids for a wide range of applications.

Spiral feed polishing uniform removal and compensation strategy of sapphire components

A single crystal sapphire component has been widely used in various high-tech fields because of its significant advantages such as high hardness, high stability, and excellent optical and mechanical properties, and has put forward high requirements for surface accuracy and quality. The existing sapphire polishing technology has problems such as low polishing efficiency, difficult control of polishing accuracy, and difficulty in removing surface defects and subsurface damage introduced by the front grinding process. Therefore, for the polishing and damage removal stage of sapphire optical components, the surface shape accuracy should be strictly controlled, especially for the surface shape accuracy after ultra-precision grinding. It is of great significance to study the uniform removal technology of grinding damage based on not destroying the surface shape. This study focuses on the mechanical polishing of sapphire. Firstly, the characteristics of the sapphire removal function of the elastic polishing tool are analyzed and the stability of the polishing tool is verified. Secondly, by establishing the relationship between the amount of workpiece material removal and the radius of rotation, the feed rate is planned to achieve the effect of uniform spiral removal. By optimizing the center feed speed of the tilting axis small-size polishing tool, the center feature of the polishing surface is controlled to be sharp. Finally, based on the sub-aperture polishing figuring theory, the influence of the center feature on the surface profile is reduced by using the spiral grating processing method. This study provides an efficient and stable strategy for the uniform removal and polishing of rotationally symmetric optical elements (such as aspheric surfaces) of high-hardness material sapphire and is expected to play a role in scenes that are particularly difficult to process, difficult to detect full aperture, difficult to calculate removal function and dwell time, such as higher steep aspheric surfaces and Gaussian aspheric surfaces.

Chemically anchored black phosphorus/chromophore composite luminescent materials towards solid-state photoluminescence and electroluminescence

As a promising two-dimensional (2D) material, black phosphorus (BP) has gained great attention because of its intrinsic physicochemical characteristics. However, BP is easy to be oxidized and form various surface defects, which decreases the charge transport and makes luminescence difficult. Herein, we report a facile strategy to synthesize chemically anchored BP/chromophore composite luminescent materials by integrating 2D BP nanosheets with boron dipyrromethene (BODIPY) dyes through simple sonication reactions. Solids of BP composite materials are brightly fluorescent with 5 orders of magnitude increase of photoluminescence intensity compared with the pure solids of BP and BODIPY. 2D BP nanosheets with large specific surface area and lone pair electrons facilitate chemisorption of BODIPY by forming covalent interactions between P and B/N atoms, which not only passivates the surface of BP and eliminates the oxidation, but also prevents the aggregation caused quenching (ACQ) issue of BODIPY. Furtherly, the organic light-emitting diodes (OLEDs) based on the BP/chromophore composite luminescent materials were first successfully achieved, the electroluminescence spectra of which cover the full spectrum of red, green, and blue visible light. This work provides a brand-new approach to further design and development of high mobility and high luminous efficiency composite luminescent materials and devices based on BP.

Laser-formed nanoporous graphite anodes for enhanced lithium-ion battery performance

Lithium-ion batteries are pivotal in modern energy storage, commonly utilizing graphite anodes for their high theoretical capacity and long cycle life. However, graphite anodes face inherent limitations, such as restricted lithium-ion storage capacity and slow diffusion rates. Enhancing the porosity of graphite and increasing d-spacing in expanded graphite anodes have been explored to improve lithium-ion diffusion and intercalation. Recent advancements suggest that nanoscale modifications, such as utilizing nano-graphite and graphene, can further enhance performance. Laser processing has emerged as a promising technique for synthesizing and modifying graphite and graphene-related materials, offering control over surface defects and microstructure. Here, we demonstrate an industrially compatible one-step laser processing method to transform a nano-graphite and graphene mixture into a nanoporous matrix, significantly improving lithium-ion battery performance. The laser-processed anodes demonstrated significantly enhanced specific capacities at all charge rates, with improved relative performance at higher charge rates. Additionally, long-term cycling at 1 C showed that laser-processed cells outperformed their non-processed counterparts, with specific capacities of 323 and 241 mAh/g, respectively.

Carbon nanomaterials for efficient oxygen and hydrogen evolution reactions in water splitting: A review

Water splitting has gained significant attention as a means to produce clean and sustainable hydrogen fuel through the electrochemical or photoelectrochemical decomposition of water. Efficient and cost-effective water splitting requires the development of highly active and stable catalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Carbon nanomaterials, including carbon nanotubes, graphene, and carbon nanofibers, etc., have emerged as promising candidates for catalyzing these reactions due to their unique properties, such as high surface area, excellent electrical conductivity, and chemical stability. This review article provides an overview of recent advancements in the utilization of carbon nanomaterials as catalysts or catalyst supports for the OER and HER in water splitting. It discusses various strategies employed to enhance the catalytic activity and stability of carbon nanomaterials, such as surface functionalization, hybridization with other active materials, and optimization of nanostructure and morphology. The influence of carbon nanomaterial properties, such as defect density, doping, and surface chemistry, on electrochemical performance is also explored. Furthermore, the article highlights the challenges and opportunities in the field, including scalability, long-term stability, and integration of carbon nanomaterials into practical water splitting devices. Overall, carbon nanomaterials show great potential for advancing the field of water splitting and enabling the realization of efficient and sustainable hydrogen production.

D2-SPDM: Faster R-CNN-Based Defect Detection and Surface Pixel Defect Mapping with Label Enhancement in Steel Manufacturing Processes

The steel manufacturing process is inherently continuous, meaning that if defects are not effectively detected in the initial stages, they may propagate through subsequent stages, resulting in high costs for corrections in the final product. Therefore, detecting surface defects and obtaining segmentation information is critical in the steel manufacturing industry to ensure product quality and enhance production efficiency. Specifically, segmentation information is essential for accurately understanding the shape and extent of defects, providing the necessary details for subsequent processes to address these defects. However, the time-consuming and costly process of generating segmentation annotations poses a significant barrier to practical industrial applications. This paper proposes a cost-efficient segmentation labeling framework that combines deep learning-based anomaly detection and label enhancement to address these challenges in the steel manufacturing process. Using ResNet-50, defects are classified, and faster region convolutional neural networks (faster R-CNNs) are employed to identify defect types and generate bounding boxes indicating the defect locations. Subsequently, recursive learning is performed using the GrabCut algorithm and the DeepLabv3+ model based on the generated bounding boxes, significantly reducing annotation costs by generating segmentation labels. The proposed framework effectively detects defects and accurately defines them, even in randomly collected images from the steel manufacturing process, contributing to both quality control and cost reduction. This study presents a novel approach for improving the quality of the steel manufacturing process and is expected to enhance overall efficiency in the steel manufacturing industry.

Electronic Structure of Rh and Ir Single Atom Catalysts Supported on Defective and Doped ZnO: Assessment of Their Activity Towards CO Oxidation.

This study investigated the electronic structure of single-atom Rhodium (Rh) and Iridium (Ir) adsorbed on defective and impurity-doped ZnO(0001) surfaces, and assessed their activity towards the CO oxidation reaction. Our findings reveal that surface impurities significantly influence the binding energies and electronic properties of the metal atoms, with Al and Cr serving as particularly effective promoters. While Rh and Ir acquire a positive charge upon incorporation on the unpromoted Zn(0001) surface, adsorption directly on the promoter results in a net negative charge, thus facilitating the activation of both CO and O2 species. These results highlight the potential of impurity-promoted ZnO surfaces in modulating and tailoring the electronic properties of SACs, which can be used for a rational design of active single-atom catalysts.

Analysis of the Impact and Mechanism of Polyacrylate-Based Composite Paste on the Performance of Recycled Aggregate.

This study developed three composite slurries for coating recycled aggregate by incorporating polyacrylate emulsion, fly ash, and gypsum into a cement-based mixture. The filling and pozzolanic effects of fly ash help to improve microcracks in the recycled aggregates. The polyacrylate emulsion forms a strong bonding layer between the cement matrix and the aggregates, enhancing the interfacial bond strength. Based on relevant studies, the following mix designs were developed: Slurry 1 consists of pure cement paste; Slurry 2 contains 15% fly ash and 3% gypsum added to the cement paste; Slurry 3 adds 22% polyacrylate emulsion to the slurry. The study first compared the effects of the three composite slurries on the crushing value and water absorption of recycled aggregates, and then analyzed their impact on the mechanical properties, permeability, and drying shrinkage of concrete. Finally, the mechanisms behind the enhancement were investigated using the Vickers Hardness Test (HV), Mercury Intrusion Porosimetry (MIP), and scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS). The results showed that the polyacrylate emulsion composite slurry had the most significant improvement effect. For recycled aggregate AL, the crushing value decreased from 28.8% to 22.5% and the saturated surface-dry water absorption decreased from 15.1% to 13.8% after cement slurry modification. After coating with the composite slurry, the crushing value further dropped to 18.2% and the water absorption to 9.5%. Two aspects of the performance of recycled aggregates are enhanced with the polymer composite slurry: first, fly ash provides nucleation sites for CH, reducing the tendency for directional CH alignment. Second, the long chains of PAE (polyacrylic ester) encapsulate cementitious particles, effectively filling surface defects on the recycled aggregates, improving the bonding strength at the new-to-old interface, and significantly enhancing the performance of both recycled aggregates and recycled concrete.

Defect Chemistry of Titanium Dioxide (Rutile). Progress Toward Sustainable Energy.

This work, which overviews defect chemistry of TiO2 (rutile), is focused on atomic-size structural defects that are thermodynamically reversible. Here it is shown that thermodynamics can be used in defect engineering of TiO2-based energy materials, such as photoelectrodes and photocatalysts. We show that surface segregation of defects leads to the building-up of new surface structures that are responsible for reactivity. Since rational design of surface properties requires in situ surface characterization in operational conditions, expansion of bulk defect chemistry to surface defect chemistry requires a defect-related surface-sensitive tool for in situ monitoring of defect-related properties at elevated temperatures corresponding to defect equilibria and in a controlled gas-phase environment. Here we show that the high-temperature electron probe is a defect-related surface-sensitive tool that is uniquely positioned to aid surface defect engineering and determine unequivocal surface properties. The related applied aspects are considered for photoelectrochemical water splitting and the performance of solid oxide fuel cells. Here we report that trail-blazing studies on in situ surface monitoring of TiO2 during gas/solid equilibration, along with in situ characterization of surface semiconducting properties, leads to the discovery of a segregation-induced low-dimensional surface structure that is responsible for stable performance of oxide semiconductors, such as TiO2, in operational conditions.

Steel Surface Defect Detection Based on YOLOv8-TLC

Steel Surface Defect Detection Based on YOLOv8-TLC

Analysis of the strength of an infinite matrix with a single-periodic array of healed cracks under torsion load

A boundary-integral approach for the study of the stress-strain state of an infinite body-matrix with single-periodic array of cracks healed by a ductile material and under static torsion loaded is proposed. The ptoblem is reduced to solving a system of 2-d boundary integral equation with respect to an unnown jump functions of shear displacements of defect surfaces.

Formation and Passivation of Surface Defects in Lead-Free Tin Halide Perovskites

Formation and Passivation of Surface Defects in Lead-Free Tin Halide Perovskites

Direct cleavage of C=O double bond in CO2 by the subnano MoOx surface on Mo2N

Compared to H2-assisted activation mode, the direct dissociation of CO2 into carbonyl (*CO) with a simplified reaction route is advantageous for CO2-related synthetic processes and catalyst upgrading, while the stable C = O double bond makes it very challenging. Herein, we construct a subnano MoO3 layer on the surface of Mo2N, which provides a dynamically changing surface of MoO3↔MoOx (x < 3) for catalyzing CO2 hydrogenation. Rich oxygen vacancies on the subnano MoOx surface with a high electron donating capacity served as a scissor to directly shear the C = O double bond of CO2 to form CO at a high rate. The O atoms leached in CO2 dissociation are removed timely by H2 to regenerate active oxygen vacancies. Owing to the greatly enhanced dissociative activation of CO2, this MoOx/Mo2N catalyst without any supported active metals shows excellent performance for catalyzing CO2 hydrogenation to CO. The construction of highly disordered defective surface on heterostructures paves a new pathway for molecule activation.