Oxide Research Articles

An insight into the electrochemical performance of nanostructured V2O5 in aqueous neutral electrolytes and fabrication of 2V, high energy density, symmetric supercapacitor

The exceptional redox characteristics, simple methods of synthesis, low cost and wide range of oxidation states of transition metal oxides like V2O5 have made them highly sought after electrode materials for supercapacitors. In the present study, V2O5 nanostructures prepared via a facile microwave-assisted method is used as the electrode material. The electrochemical performances of this electrode material is analysed in four different aqueous neutral electrolytes. The nature of the ions present in the electrolytes are found to have a significant influence on the performance of the electrode, achieving the highest specific capacitance values in KCl electrolyte while highest potential window and stability in Na2SO4 electrolyte. The symmetric supercapacitor fabricated using the Na2SO4 electrolyte exhibits a specific capacitance value of 82.35 F g-1 and a specific energy of 45.75 Wh kg-1 at a specific power of 1000 W kg-1. Moreover, the device retains 70 % of its initial capacitance even after 10,000 charge-discharge cycles at a current density of 5 A g-1. An asymmetric supercapacitor is also fabricated using KCl electrolyte after optimizing the mass-ratio of positive and negative electrodes using Ragone plot simulator. The asymmetric supercapacitor exhibits a specific capacitance of 34 F g-1 with an energy density and power density of 11 Wh kg-1 and 775 W kg-1 respectively. The present study summarizes the effect of different neutral electrolytes on the electrochemical performance of V2O5 nanostructured electrodes. The physiochemical properties of ions such as solvation, diffusion and mobility, and their influence on the electrochemical behaviour are also taken in to account to explain the observed electrode performance.

Structural, optical, antibacterial, antifungal, and anticancer activity of sodium alginate-pluronic-F127-tin dioxide nanoparticles prepared via microwave-assisted green process

The green synthesis of inorganic metal oxide nanoparticles is essential because it reduces environmental impact and enhances biocompatibility by using eco-friendly materials and processes. This sustainable approach also minimizes hazardous chemicals, promoting safer and cleaner production methods. The sodium alginate-Pluronic F127-modified SnO2 (SAPFSO) NPs were prepared using the green method using Psidium guajava leaf extract. The SAPFSO NPs exhibit a tetragonal rutile structure from the X-ray diffraction patterns. The FESEM and EDAX spectra identified the morphology and chemical composition. The Sodium Alginate, Pluronic-F127, and SnO2 functional group vibrations can be seen in the FTIR spectra. The DLS spectra and hydrodynamic sizes of SAPFSO NPs were observed at 183 nm. The various surface defects of SAPFSO NPs were identified from the PL spectrum. The antimicrobial activity of SAPFSO NPs was tested against gram-positive and gram-negative strains such as S. aureus, K. pneumoniae, S. dysenteriae, S. pneumoniae, Bacillus megaterium, Proteus valgaris, and Candida albicans fungal strain using the well-diffusion method. To increase the concentration, SAPFSO NPs also increased the antimicrobial activity. The anticancer activity of SAPFSO NPs tested against the human breast cancer cell line (MDA-MB-237). SAPFSO NPs exhibits potential anticancer activity against triple negative breast cancer cell line. These results support that SAPFSO NPs can be applied in healthcare and industrial settings to improve human health.

NH2-MIL-125(Ti-Zr) synergized with WO3 to construct S-Scheme heterojunction photocatalysts for highly efficient degradation of organic dyes and tetracycline in water

The rapid treatment of organic dyes and tetracycline (TC) in industrial wastewater requires highly efficient semiconductor photocatalysts. In this study, the S-Scheme NH2-MIL-125 (Ti-Zr)/ WO3 composite material was successfully synthesized using a two-step hydrothermal method. A comprehensive analysis using X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), High Resolution Transmission Electron Microscopy (HRTEM), and Field Emission Scanning Electron Microscopy (FESEM) images revealed that WO3 nanoparticles are intimately anchored on the NH2-MIL-125 (Ti-Zr) nanodisks, forming a closely packed heterostructure. The bandgap values of WO3 and NH2-MIL-125 (Ti-Zr) were determined to be 2.58 eV and 2.67 eV, respectively. Through Response Surface Methodology (RSM), the optimal photocatalytic conditions for the degradation of simulated pollutants in real aqueous environments by the synthesized photocatalysts were explored. Under the full-spectrum irradiation of a 300 W xenon lamp, the TZW-2 composite photocatalyst exhibited a degradation rate of RhB, MB, and TC solutions as high as 95.7 %, 96.7 %, and 93 % within 90 min, respectively. The excellent photocatalytic performance of the composite photocatalyst originates from the establishment of S-scheme heterojunctions between NH2-MIL-125 (Ti-Zr) and WO3, which was confirmed by various characterization techniques such as XPS valence spectra, photoelectrochemistry, and free radical trapping experiments. The excellent stability of the prepared composite photocatalyst was further validated through three cycling test experiments. This work presents new ideas for constructing novel S-Scheme photocatalysts by combining bimetallic cluster MOFs and metal oxides for wastewater treatment.

Product differentiation of Sarawak premium rice using MOS gas sensors: comparison between transient and frequency response

In Malaysia, rice, ranked as the third most crucial crop, faces challenges due to domestic consumption outpacing production, resulting in increased instances of rice adulteration. This underscores the imperative of maintaining integrity and quality standards across the entire supply chain. This study uses an electronic nose, comprising four metal oxide semiconductor (MOS) gas sensors, and employing temperature modulation, Principal Component Analysis (PCA) and supervised machine learning (classification models) to distinguish rice varieties such as Bario, Bajong, Borneo Fragrant, Biris, and Jasmine. The study evaluated 30 classifiers based on their classification and validation accuracy. Sensor data was first extracted from the transient response of sensors output voltage, yielding a 12-dimension dataset with response times of 30 s, 50 s, and 95 s. Classification models trained from this dataset achieved classification (training) accuracy of up to 100% and validation accuracy of up to 96%, where the best performing models are subspace discriminant and kernel naïve bayes classifiers. An attempt was also made to analyze the sensor data frequency response for rice classification. Comparison between the prediction results in the transient and frequency domains showed that transient response is better suited for the classification of rice.

Zinc manganite as an efficient battery-grade material for supercapattery devices

In the current context, supercapatteries emerge as highly desirable candidates capable of merging both energy and power density within a single device. Battery-type metal oxide materials, combined with capacitive-based materials, stand out as promising candidates for high-performance supercapatteries. This investigation centers on the synthesis of nanocrystalline ZnMn2O4 (ZMO) and CoMn2O4 (CMO) through a straightforward hydrothermal method, followed by their physico-electrochemical characterization. Electrochemical analysis reveals that ZMO exhibits notably enhanced charge storage capability compared to CMO. This superiority can be attributed to favourable electro-structural properties, and stable redox chemistry of ZMO. The real-time performance of ZnMn2O4 was further assessed by fabricating a hybrid asymmetric supercapattery device (ZnMn2O4||NrGO), which achieves a specific capacity of 232 C g−1 at a current density of 1 A g−1. The hybrid asymmetric device underwent rigorous stability testing for 4000 cycles at a current density of 2 A g−1, showcasing remarkable performance with a 92 % retention of its initial capacity. The device demonstrated a power density of 980 W kg−1 and an energy density of 63 Wh kg−1, highlighting its considerable promise in the field.

Optimizing symmetric supercapacitor performance through rational design of Zr/Cu/Fe Oxide-Modified Poly(vinyl alcohol) hybrid nanofibers

Present work, ZrO2/CuO/PVA (ZC-PVA), ZrO2/Fe2O3/PVA (ZF-PVA) and ZrO2/CuO/Fe2O3/PVA (ZCF-PVA) nanofibers were synthesized by cost effective electrospinning method. The ZCF-PVA nanofiber prepared in this study were subjected to analysis using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) techniques, individually. XRD was employed to ascertain both the structure and crystallite size of the synthesized materials. SEM and FT-IR analysis were used to identify the morphology and functional groups present in the prepared ZC-PVA, ZF-PVA and ZCF-PVA nanofibers. XPS confirmed the surface elemental composition and oxidation states of Zr4+, Cu2+, and Fe3+ in ZCF-PVA nanofiber comprising ZrO2, CuO, and α-Fe2O3. In three electrode configuration ZCF-PVA nanofiber shows significantly higher specific capacitance of 824F/g at 1 A/g current density under 1 M KOH. The generation of synergic effect between multi valence oxidation states of mixed metal oxides and polymer (ZCF-PVA) enhances the capacitive behavior. The ZCF-PVA symmetric device exhibits 184F/g at 0.5 A/g current density with 91 % capacitance retention and 94 % of coulombic efficiency even after 5000 cycles at 3 A/g of current density.

Order-Disorder Transition in Rutile VO2(M) Electrodes during Li Intercalation and Extraction.

Transition metal oxides are widely employed as electrode materials in Li-ion batteries. During battery operation, Li ions are intercalated and extracted from the framework of the electrode structure, causing structural transitions. In some materials, the process can drive order-disorder transitions; however, insights into such processes are generally lacking, although they are essential for our understanding of battery aging and in the design of new sustainable battery chemistries. Herein, we investigate the intercalation-induced order-disorder transition in rutile VO2(M) electrodes by means of galvanostatic charge/discharge cycling, operando powder X-ray diffraction, and total X-ray scattering with pair distribution function analysis. The study reveals that the rutile structure transforms irreversibly into a highly disordered layered Li x VO2 structure, which is capable of reversibly intercalating Li ions. Our findings point out general trends for the intercalation-driven transitions in rutile oxides.

Single-crystalline HfO2 nanostructures with novel ferromagnetic properties

Hafnium oxide (HfO2) has special technological significance due to its superior properties such as high dielectric constant (κ∼25), wide bandgap (∼5.7 eV), and superb thermal and chemical stabilities. Its room-temperature ferromagnetism and excellent CMOS technology compatibility make it a promising candidate for seamless CMOS-spintronics integration. Low-dimensional single-crystalline HfO2 nanostructures, particularly one dimensional (1D) nanostructures, are expected to exhibit enhanced ferromagnetic properties due to large specific surface areas and potentially more surface defects. To date, the synthesis of single-crystalline HfO2 1D nanostructures has, however, remained elusive. Here, single-crystalline dopant-free HfO2 nanostructures with notable morphologies, including HfO2 1D nanostructures, are grown using catalyst-assisted pulsed laser deposition. It is shown that Sn plays a crucial role in producing these 1D nanostructures by increasing both the VLS nucleation and growth rates. Magnetization measurements reveal room-temperature ferromagnetism in HfO2 nanowires, contrasting with weak paramagnetic responses in HfO2 nanostructured films. We also provide the first direct evidence of oxygen vacancies as the source of room-temperature ferromagnetism in HfO2. To account for the observed magnetic property, we employ a modified bound magnetic polaron-band ferromagnetism hybrid model, which is also generally applicable to dopant-free nanostructures of other metal oxides. This work provides new insights into the growth of novel metal oxide 1D nanostructures and the design of new dilute magnetic semiconducting oxides for potential integrated CMOS-spintronics applications.

Corrosion evaluation of austenitic stainless steels in Li2CO3-K2CO3 eutectic salt for thermal energy storage

Molten carbonate salt is one of the promising candidates for high-temperature thermal energy storage tailored towards advanced pumped-thermal energy storage and next generation concentrated solar power technologies. However, severe corrosion of structural materials exposed to molten carbonate salts poses one of the most pivotal threats in terms of limiting their large-scale application at ever-escalating temperatures. Here, we elaborate the compatibility of three commercial austenitic stainless steels specifically SS310, SS316L and Incoloy 625 with Li2CO3-K2CO3 (28–72 wt%) eutectic salt. The corrosion behavior and corrosion mechanism of Fe-Cr (SS316L), Fe-Cr-Ni (SS310) and nickel-based (In625) alloys at 600 °C in air were also investigated. It revealed that SS310 exhibited better corrosion resistance compared to SS316 and In625, with weight loss of 23.8 mg/cm2 and corrosion rate of 522 μm/year after 500 h of exposure at 600 °C. This implies that higher Ni content of the alloy may not necessarily improve the corrosion resistance, it is associated with the basicity of the molten and the solubility of Ni salt in the melt. ICP analysis indicated that the salts exposed to SS310 and In625 at the same exposure time both had nearly 11 times more Ni than that exposed to SS316. Precisely, it is related to the behavior of the Cr-enriched zones formed in the corrosion layers of different alloys. The corrosion mechanism of SS310 specimens in molten carbonate can be generally divided into the following steps: (i) selective oxidation of the metal elements and lithiation reactions of the metal oxides to generate a passivation scale, (ii) an ever-growing middle transition scale consisted of mixed metal oxides and lithium-containing compounds, (iii) cracking and peeling off of the corrosion scale.

Hollow porous silica nanoreactors encapsulating VOx-decorated Pt nanoparticles for the reverse water–gas shift reaction

Reverse water–gas shift (RWGS) reaction is a desirable strategy for achieving CO2 utilization and enhancing CO production. Due to the endothermic nature and the chemical equilibrium of this reaction, the reaction is typically conducted at high temperatures (300 ∼ 1000 °C); however, high temperature conditions lead to the sintering of the catalyst, resulting in a catalyst deactivation. Herein we report the synthesis of a metal oxide (V or Mo oxide)-decorated Pt nanoparticles encapsulated in hollow porous silica nanoreactors (HPSNs) by a W/O micro-emulsion system using branched poly(ethyleneimine) (PEI) as a sacrificial metal–ligand. The HPSNs encapsulating VOx-decorated Pt nanoparticles (Pt-VOx@HPSNs) afforded a 1.8-fold increased activity in RWGS reaction at 500 °C compared with Pt@HPSNs with a net CO production rate of 1140.3 mmol/gcat/h and with nearly 100 % CO selectivity. In situ XAFS measurement and reaction kinetic analysis reveal that the interplay of Pt nanoparticles and the decorated V oxide, which simultaneously activate H2 and CO2, respectively, leads to a lowering of the activation energy and a faster CO production rate. Furthermore, the Pt-VOx@HPSNs catalyst retains over 92 % activity after 50 h of continuous operation at 500 °C with the aid of a protective silica shell. This work offers a strategy for the design and development of an efficient and stable heterogeneous catalyst for RWGS reactions.

Assessment of 'Golden Delicious' Apples Using an Electronic Nose and Machine Learning to Determine Ripening Stages.

Consumers often face a lack of information regarding the quality of apples available in supermarkets. General appearance factors, such as color, mechanical damage, or microbial attack, influence consumer decisions on whether to purchase or reject the apples. Recently, devices known as electronic noses provide an easy-to-use and non-destructive assessment of ripening stages based on Volatile Organic Compounds (VOCs) emitted by the fruit. In this study, the 'Golden Delicious' apples, stored and monitored at the ambient temperature, were analyzed in the years 2022 and 2023 to collect data from four Metal Oxide Semiconductor (MOS) sensors (MQ3, MQ135, MQ136, and MQ138). Three ripening stages (less ripe, ripe, and overripe) were identified using Principal Component Analysis (PCA) and the K-means clustering approach from various datasets based on sensor measurements in four experiments. After applying the K-Nearest Neighbors (KNN) model, the results showed successful classification of apples for specific datasets, achieving an accuracy higher than 75%. For the dataset with measurements from all experiments, an impressive accuracy of 100% was achieved on specific test sets and on the evaluation set from new, completely independent experiments. Additionally, correlation and PCA analysis showed that choosing two or three sensors can provide equally successful results. Overall, the e-nose results highlight the importance of analyzing data from several experiments performed over a longer period after the harvest of apples. There are similarities and differences in investigated VOC parameters (ethylene, esters, alcohols, and aldehydes) for less or more mature apples analyzed during autumn or spring, which can improve the determination of the ripening stage with higher predicting success for apples investigated in the spring.

Synthesis of Z-scheme amorphous WO3-loaded TiO2 photocatalyst for enhanced photocatalytic degradation of dichloromethane: Internal electric field and mechanism exploration

Photocatalytic technology is a highly efficient means for treatment of volatile organic compounds (VOCs) and mitigation of environmental issues. In this study, we successfully prepared the Z-scheme WO3/TiO2 heterojunction catalyst through the impregnation sintering process. The photocatalytic performance of dichloromethane (DCM) was examined by monitoring its concentration changes under ultraviolet light irradiation. The results demonstrated that 3 % WO3/TiO2 exhibited the most excellent performance, achieving a degradation performance of 98 % under a continuous airflow of 0.8 L/min and an initial DCM concentration of 200 ppm. Importantly, the catalyst maintained its performance without any significant decrease even after 100 h of continuous testing. The excellent performance was mainly thanks to built-in electric field and narrower bandgap, which effectively reduced electron and hole complexation, thereby increasing the production of more reactive oxygen species. Gas phase capture testing revealed that •O2- radicals played a crucial role in DCM degradation. Additionally, the improvement of surface acidity by WO3 and preferential breaking of C-Cl bond effectively prevented the production of phosgene (COCl2). This research finding addresses the gap in the understanding of photocatalytic degradation of DCM with TiO2 modified by metal oxides and lays a strong foundation for future industrial applications.

Recent progress of high-energy density supercapacitors based on nanostructured nickel oxides

With the progressive demand of portable devices and hybrid electronic vehicles, relevant energy storage options are one of the most important practical necessities. Supercapacitors may play a key role for developing auto electronic advanced tools, because of their specific power density, fast charging capacity, and long-life time. On the other hand, nanostructured materials for supercapacitor electrodes have demonstrated great potential for constructing a reliable as well as efficient gateway for betterment. Nanostructured form of metal oxides, especially nickel oxide (NiO), is one of the most excel material to design high performance supercapacitors. This review deals with a detailed discussion on some fundamental aspects of supercapacitors incusing variety, performance evaluation criteria, and influencing factors for designing high density supercapacitors. Along with these, recent effective strategical approaches for generating high energy density supercapacitors utilizing NiO and their composites are particularly described the inherent performance influencing factors like their physical, chemical, and compositional variations. Finally, upgrading the next generation devices, the commercial application, challenges, and future prospects of the recently developed NiO-based supercapacitor materials are pointed out.

Enhanced NH3-SCR performance using hydrothermally synthesized cell-like MnOx loaded rectorite catalysts

This study evaluates the catalytic performance of hydrothermally synthesized MnOx loaded rectorite catalysts (MnOx/REC-HP) in the selective catalytic reduction of NH3-SCR. Comparative analyses were conducted with catalysts synthesized via pore-volume impregnation, coprecipitation, and in-situ deposition methods, all yielding comparable manganese mass fractions. Results reveal that catalysts derived from hydrothermal synthesis outperform others in NH3-SCR activity across the 100–300 °C temperature spectrum. MnOx/REC-HP exhibits a distinctive cell-like structure of supported MnOx atop the rectorite substrate, diverging from the particulate patterns observed in other synthesis methods. Hydrothermal synthesis of metal precursors into their respective metal oxides effectively meets the fundamental requirements for SCR composites. This method enables the production of composites that are uniformly attached to nanostructures with high purity and controlled crystallinity. The rectorite surface is embellished with a meticulously arranged honeycomb structure of MnOx, augmenting the BET surface area, intensifying redox capability, enhancing NH3 and NOx adsorption, and amplifying the Mn4+ molar ratio on the catalyst surface. Consequently, MnOx/REC-HP showcases remarkable low-temperature NH3-SCR performance.

Hydrogen Production from Ammonia Decomposition: A Mini-Review of Metal Oxide-Based Catalysts.

Efficient hydrogen storage and transportation are crucial for the sustainable development of human society. Ammonia, with a hydrogen storage density of up to 17.6 wt%, is considered an ideal energy carrier for large-scale hydrogen storage and has great potential for development and application in the "hydrogen economy". However, achieving ammonia decomposition to hydrogen under mild conditions is challenging, and therefore, the development of suitable catalysts is essential. Metal oxide-based catalysts are commonly used in the industry. This paper presents a comprehensive review of single and composite metal oxide catalysts for ammonia decomposition catalysis. The focus is on analyzing the conformational relationships and interactions between metal oxide carriers and active metal sites. The aim is to develop new and efficient metal oxide-based catalysts for large-scale green ammonia decomposition.

Phosphorous-doped nickel-cobalt bimetallic molybdate/three-dimensional hierarchical porous carbon for high-efficiency solid-state supercapacitors

The limited electrical conductivity and insufficient quantity of electrochemically active sites in transition-metal oxides impede their extensive utilization in high-performance supercapacitors. Herein, we present a successful synthesis of phosphorus-doped NixCo1-xMoO4 (P-NCMO) on three-dimensional hierarchical porous carbon (HPC) derived from enzymatically hydrolyzed lignin through a co-precipitation pathway and subsequent phosphorylation process. The electrochemical performance was improved by optimizing the content of P doping. Additionally, the incorporation of phosphorus into P-NCMO led to a decrease in Co-O bonding energy and facilitated the formation of molybdenum species with lower oxidation states, thereby enhancing surface redox chemistry and improving electrochemical performance. As a result, the optimized HPC/P-NCMO-2 electrode exhibits a high specific capacity of 1003 C g−1 at a current density of 1 A g−1, and it maintains 89.87 % of its initial capacity after 10,000 cycles at a current density of 1 A g−1. The optimized HPC/P-NCMO-2 assembled as the positive electrode and activated carbon as the negative electrode in an asymmetric supercapacitor delivers a high energy density of 94.7 Wh kg−1 at a power density of 800 W kg−1, while maintaining excellent cycle life.

Design of SEE-Tolerant analog switch chip with a novel diode structure *

This paper proposes a novel circuit-level design in order to enhance the radiation tolerance of an analog switch integrated circuit. After analyzing the mechanisms of single-particle sensitivity in a high-voltage analog switch chip fabricated using a commercial 1 μm complementary metal–oxide–semiconductor process, a diode unit was employed to reduce the V GS (voltage between the gate and the base) of the parasitic triode within the metal–oxide–semiconductor field-effect transistor of the switch. This reduction lowered the probability of activating the parasitic triode in response to single-event effect (SEE). Subsequently, single-particle irradiation experiments proceeded with the high-voltage analog switch chip, both with and without the diode unit. In the unreinforced device, the current of the power supply reached 100 mA within 11 s of single-particle irradiation at 75.8 MeV•cm2 mg−1. In contrast, in the reinforced device, the current of the power supply remained relatively stable under irradiation at both 37.2 and 75.8 MeV•cm2 mg−1. These findings indicate that the reinforced analog switch chip exhibits an SEE tolerance exceeding 75.8 MeV•cm2 mg−1, highlighting its potential to enhance the radiation tolerance of analog switches.

Hierarchical triplet-metallic oxide/carbon nanocomposites constructed from 2D layered double hydroxides and metal-organic frameworks for high-performance microwave absorption

In the face of increasingly severe electromagnetic wave radiation and interference, it is of great significance to design and prepare excellent absorbing materials. Particularly, hierarchical structure has emerged with enhanced physicochemical properties, offering enormous potential for designing absorbing materials. Here, a hierarchical structure composite constructed by ZIF-8 and fungus-like nickel-cobalt layered double hydroxide (Ni, Co-LDH) nanosheets were synthesized by in-situ self-assembly growth process. A series of Zn@NiCo-Lc composites were obtained by calcination under air. Calcined derivatives of dielectric and magnetic metallic oxides and carbon give rise to multiple polarizations and magnetic losses. The matching of the dielectric and magnetic losses of the hybrid material is further tuned by varying the feed ratio of the bimetallic LDH nanosheets, resulting in a sample with tunable EMA performance. All samples exhibit comparable EMA performance, especially large EABmax of above 5.5 GHz, and Zn@NiCo-Lc-2 has the strongest EMA intensity performance (RLmin is −67.61 dB at an ultra-thin thickness of 1.71 mm). This study provides a tractable method for the fabrication of hierarchical structural composites of high-performance MOF/LDH-derived absorbers, further broadening the application and development of novel electromagnetic wave absorption materials.

Comparative investigation on the performance of spot positioning sensors in point-autofocus microscopy

As products evolve towards greater precision and intelligence, their components also develop towards miniaturisation and increasing complexity. In the era of intelligence, the demand for complex small components continues to grow. The point-autofocus microscopy (PAM), with its attributes such as small measurement spots and high vertical resolution, holds a comprehensive advantage in instruments for measuring the geometry of complex small components. The performance of the spot positioning sensor directly determines the capability of the PAM to measure complex small components. This study introduces the basic measurement principles of the PAM and commonly used spot positioning sensors. The analysis explored the feasibility of applying different sensors to the PAM. An automatic segmentation and weighted localisation algorithm of the spot based on the centroid method was proposed. Using this algorithm, the spot positioning error of the complementary metal–oxide–semiconductor (CMOS) sensor can be controlled within 0.48 μm, with a measurement uncertainty of no more than ±0.19 μm. This study focuses on comparing the performance of CMOS and position-sensitive detector sensors with the performance of seven indicators. In addition, a measurement system of the PAM was constructed, and measurements of the test object were conducted using both types of sensors. The experimental results show that when the measurement system employs the CMOS sensor, it achieves higher measurement accuracy. The maximum measurement error was approximately 0.22 μm, with a measurement uncertainty of no more than ±0.10 μm.

Optimizing substrate bias voltage to improve mechanical and tribological properties of ductile FeCoNiCu high entropy alloy coatings with FCC structure

Conventional hard coatings are limited in their tribological applications due to their high brittleness. High-entropy alloy (HEA) coatings, which combine high toughness and hardness, represent a new class of tribological coatings with great potential. The microstructure and stress state of HEA coatings can be significantly affected by the deposition parameters of magnetron sputtering, which can regulate their mechanical and tribological properties. In this study, DC magnetron sputtering with varying substrate bias voltages was used to deposit FeCoNiCu HEA coatings with an FCC single phase structure on 316 stainless steel. The microstructure, mechanical, and tribological properties of these coatings were studied in detail. The residual tensile stress of the coatings decreases, while toughness and hardness increase as the bias voltage increases. The coatings exhibited optimal toughness, highest hardness (11.3 GPa), and the lowest wear rate (as low as 6.01 × 10−5 mm3/N·m) when the bias voltage was set to −200 V. The formation of a metal oxide adhesion layer during friction improved the tribological properties of the coatings. This study demonstrates that optimizing the deposition bias voltage is an effective way to improve the mechanical and tribological properties of high-entropy, face-centered cubic alloy coatings, which are intrinsically tough and ductile.