Search Results (92)

Titanium dioxide (TiO₂) is a versatile material that exhibits a high refractive index, strong light-scattering capability, effective UV-absorption, wide band gap semiconductor behavior (3.0–3.2 eV), and excellent chemical stability. Owing to this unique combination of properties, TiO₂ is widely used in applications such as cosmetic and healthcare products, architectural and automotive coatings, and photocatalytic degradation of environmental pollutants. In photocatalytic applications, the crystal structure, phase composition and electronic properties of TiO₂ play a critical role in determining its performance. In the present study, TiO₂ nanotubes were synthesized by anodization of Ti° coatings deposited via a semi-industrial arc-PVD process. A post-anodization heat treatment was carried out at 430 °C for 1 h to promote the formation of the anatase phase within the TiO₂ nanotube structures. The structural characterization of the synthesized film was performed using X-ray diffraction (XRD) and Rietveld refinement. This methodology enabled the identification of the formed oxide phases, structure, and crystalline, confirming the formation of mixed oxides in the coating. To address the difficulty of refinement of these crystalline phases, the Le Bail method was applied. This refinement strategy allowed the identification of the crystalline phases that are present in the Ti_xO_y coating, including a hexagonal structure characteristic of α-Ti (space group P63/mmc, No. 194), the tetragonal anatase TiO₂ (space group I41/amd, No. 141) phase, and the trigonal Ti₂O₃ phase (space group R-3/c No. 167). Key crystallographic parameters such as lattice constants, bond lengths and angles, crystallite sizes, unit cell distortion and electron density were systematically evaluated for each phase. In addition, the Wyckoff positions and interatomic distances of the constitutive atoms were calculated, providing a comprehensive description of the TiO₂+Ti₂O₃/Ti° crystallographic system. The topographic and surface oxidation states were recorded by using profilometry and X-ray photoelectron spectroscopy, respectively. Full article

Scale-up synthesis in doped semiconductor metal oxide plasmonic nanocrystal batch reaction dispersion mixture processes often leads to significant changes in rheological behavior and flow characteristics, especially when using high-viscosity organic media. In this study, the rheological and hydrodynamic properties during the scale-up of a nanocrystal dispersion system where oleyl alcohol was used as a reaction solution medium were investigated. The flow field in a mechanically stirred 4 L pilot reactor was numerically analyzed using ANSYS Fluent based on experimentally obtained viscosity and density data of oleyl alcohol. At 290 °C, coincident with the nucleation and growth of plasmonic-doped metal oxide nanocrystals, solvent viscosity decreases to a corresponding Reynolds number of 9.2 × 10⁵, indicating that the dramatic viscosity reduction in oleyl alcohol above synthetic temperature batch reaction conditions drives a sharp increase in Reynolds number into a strongly turbulent mixing regime at synthetically relevant temperatures. The simulation results revealed that the scale-up process induces notable variations in shear rate distribution, local turbulence intensity, and overall mixing efficiency. These findings suggest that understanding rheological transitions under scale-up conditions is essential for optimizing nanoparticle synthesis and dispersion uniformity in industrial applications. Full article

We have fabricated amorphous tin oxide (a-SnO_x) thin-film transistors (TFTs) with Al₂O₃ gate insulator from deep eutectic solvents (DESs). DESs were formed using the chloride derivates of each precursor (SnCl₂, or AlCl₃) mixed with urea. The DESs were then used as precursors for the semiconductor and dielectric. Our target was to form extremely thin semiconductor film, and a sufficient high capacitance insulator. We characterized the physical and chemical properties of the DES-derived thin films by X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). We could evaluate that the highest content of metal–oxygen bonds was from the DES condition SnCl₂–urea = 1:3. At a low 300 °C budget temperature, we could fabricate a 3.2 nm thick a-SnO_x layer and 30 nm thick Al₂O₃, from which the TFT demonstrated a mobility of 80 ± 17 cm²/Vs, threshold voltage of −0.29 ± 0.06 V, and subthreshold swing of 88 ± 11 mV/dec. The proposed process is adequate with the back-end of the line (BEOL) process, but it is also eco-friendly because of the use of DESs. Full article

This study explored the oxygen-sensing mechanism of CeO₂ modified with TiO₂ via high-energy ball milling at different speeds. Different characterization techniques were employed to investigate the obtained materials. Quantitative surface analysis by X-ray photoelectron spectroscopy was conducted to elucidate their sensitivity mechanisms and assess the impact of the introduction of TiO₂. A comparable concentration of oxygen vacancies was found in the samples milled at 350 and 450 rpm. Electrical measurements conducted at temperatures lower than required for semiconductor gas sensors revealed the higher sensitivity of these two samples in comparison to pure CeO₂ at an oxygen concentration above 10%. In contrast, the samples derived from precursors milled at the highest speed exhibited the lowest sensitivity. This may be linked to a slight decrease in the vacancy concentration and the presence of a differentially charged carbon-containing phase. Eventually, the C 1s line provided significant insight into the surface characteristics of the materials. The uniform and non-uniform charging found for pure TiO₂ and CeO₂, respectively, along with the high charging of CeO₂, suggest that TiO₂ promotes the contact between the sensing layer and the overlayer. Sensor testing showed the significantly lower resistance of mixed oxides in comparison to CeO₂, which increases the utility of metal oxide-based sensors. Full article

We evaluated the efficacy of an innovative technique using an S3+ device equipped with two custom-made nanosensors (e-nose). These sensors are integrated into kitchen appliances, such as planetary mixers, to monitor and assess dough leavening from preparation to the fully risen stage. Since monitoring in domestic appliances is often subjective and non-reproducible, this approach aims to ensure safe, high-quality, and consistent results for consumers. Two sensor chips, each with three metal oxide semiconductor (MOS) elements, were used to assess doughs prepared with flours of varying strengths (W200, W250, W390). Analyses were conducted continuously (from the end of mixing to 1.5 h of leavening) and in two distinct phases: pre-leavening (PRE) and post-leavening (POST). The technique was validated through solid-phase micro-extraction combined with gas chromatography–mass spectrometry (SPME-GC-MS), used to analyze volatile profiles in both phases. The S3+ device clearly discriminated between PRE and POST samples in 3D Linear Discriminant Analysis (LDA) plots, while 2D LDA confirmed flour-type discrimination during continuous leavening. These findings were supported by SPME-GC-MS results, highlighting differences in the volatile organic compound (VOC) profiles. The system achieved 100% classification accuracy between PRE and POST stages and effectively distinguished all flour types. Integrating this e-nose into kitchen equipment offers a concrete opportunity to optimize leavening by identifying the ideal endpoint, improving reproducibility, and reducing waste. In future applications, sensor data could support feedback control systems capable of adjusting fermentation parameters like time and temperature in real time. Full article

The communication module is crucial for control systems. Under thermal, electrical, and mechanical stresses, sensitive digital and analog components may degrade in performance or fail, compromising the module’s long-term stability. Existing reliability-prediction methods, however, do not fully leverage multi-physics simulations to model stress-induced failure modes, leading to limited confidence in their predictions. This article proposes a systematic method to enhance the reliability prediction of mixed-signal electronic systems under complex operating conditions. First, we identify the key Complementary Metal-Oxide-Semiconductor (CMOS) chips and their associated failure mechanisms. Then, we use an I/O Buffer Information Specification-based (IBIS-based) topology to build a hybrid-precision simulation that models electrical stress. A Verilog-SPICE framework is employed to simulate component degradation and failure modes. Subsequently, by including mission profiles, we perform a simplified multi-physics coupling analysis to evaluate the effects of temperature and mechanical stress on failure mechanisms. Finally, the Physics of Failure models of components are integrated to derive the reliability curve of the module, and targeted optimization strategies are proposed. Compared to conventional methods, the method combines hybrid-precision simulation with multi-physics coupling modeling, improving the accuracy of critical failure modes. This method enhances the quantitative product reliability analysis and provides valuable support for optimized design. Full article

With advances in space, nuclear, and defense industries, the susceptibility of semiconductor integrated circuits (ICs) to radiation has increased. Radiation-induced degradation and malfunctioning of IC performance can lead to system failure, leading to significant damage. To address this limitation, this study employed mixed-stage modeling and simulation (M&S) techniques to evaluate the reliability of complementary metal-oxide semiconductor application-specific ICs (ASICs) in radiation environments. Radiation-hardened IC chips were designed and fabricated using layout modification techniques based on M&S. The ASIC, which includes the D-latch and Operational Amplifier (Op-Amp) circuits, was validated for resistance up to a total ionizing dose of 20 kGy(Si). The proposed radiation-hardened ICs demonstrated stable performance even in radiation-exposed environments, ensuring reliable operation under such conditions. The findings provide insights into overcoming radiation-induced degradation and malfunction in semiconductor integrated circuits, which is particularly relevant for advancing space, nuclear, and defense industries. Full article

This study investigates the surface energies and work function changes in ZnGa₂O₄(111) surfaces with different atomic terminations using ab initio density functional theory. It explores the interactions of gas molecules such as NO, NO₂, and CH₃COCH₃ with Ga-terminated, O-terminated, and Ga-Zn-O-terminated surfaces. This study reveals previously unreported insights into how O-terminated surfaces exhibit enhanced reactivity with NO, resulting in significant work function changes of +6.42 eV. In contrast, Ga-terminated surfaces demonstrate novel interactions with oxidizing gases, particularly NO₂, with a notable reduction in work function change of −1.63 eV, offering potential gas sensor technology advancements. Particularly notable is the Ga-Zn-O-terminated surface, which presents mixed characteristics influenced by the interplay of oxygen and metallic elements (gallium and zinc), leading to substantial work function changes of +4.97 eV for NO and +1.82 eV for NO₂, thereby significantly enhancing sensitivity. This study unveils the previously unexplored roles of Ga-Zn-O-terminated ZnGa₂O₄ surfaces in optimizing semiconductor-based gas sensors, offering both oxidative and reductive potentials and making them versatile for diverse applications. Full article

Bentonite-supported TiO₂ (Montmorillonite (MMT)-TiO₂) and Cu₃TiO₅ oxides (MMT-Cu₃TiO₅) nanomaterials were synthesized via a facile and sustainable sol–gel synthesis approach. The XRD results indicate the presence of mixed phases, namely, TiO₂ anatase and a new semiconductor, Cu₃TiO₅, in the material. The specific surface area (S_BET) exhibits a notable increase with the incorporation of TiO₂ and Cu₃TiO₅, rising from 85 m²/g for pure montmorillonite to 245 m²/g for MMT-TiO₂ and 279 m²/g for MMT-Cu₃TiO₅. The lower gap energy of MMT-Cu₃TiO₅ (2.15 eV) in comparison to MMT-TiO₂ (2.7 eV) indicates that MMT-Cu₃TiO₅ is capable of more efficient absorption of visible light with longer wavelengths. The immobilization of TiO₂ and Cu₃TiO₅ on bentonite not only enhances the textural properties of the samples but also augments their visible light absorption capabilities, rendering them potentially more efficacious for adsorption and photocatalytic applications. The photocatalytic efficacy of both MMT-TiO₂ and MMT-Cu₃TiO₅ was evaluated through the monitoring of the degradation of Orange G, an anionic azo dye. The MMT-Cu₃TiO₅ photocatalyst was observed to induce complete degradation (100%) of the Orange G dye in 120 min when tested in an optimized reaction medium with a pH of 3 and a catalyst concentration of 2 g/L. MMT-Cu₃TiO₅ was demonstrated to be an exceptionally effective catalyst for the degradation of Orange G. Following the synthesis of the catalyst, it can be simply washed with the same recovered solution and reused multiple times for the photocatalytic process without the need for any chemical additives. Full article

To solve the energy crisis and environmental issues, it is essential to create effective and sustainable energy conversion and storage technologies. Traditional materials for energy conversion and storage however have several drawbacks, such as poor energy density and inadequate efficiency. The advantages of MOF-based materials, such as pristine MOFs, also known as porous coordination polymers, MOF composites, and their derivatives, over traditional materials, have been thoroughly investigated. These advantages stem from their high specific surface area, highly adjustable structure, and multifunctional nature. MOFs are promising porous materials for energy storage and conversion technologies, according to research on their many applications. Moreover, MOFs have served as sacrificial materials for the synthesis of different nanostructures for energy applications and as support substrates for metals, metal oxides, semiconductors, and complexes. One of the most intriguing characteristics of MOFs is their porosity, which permits space on the micro- and meso-scales, revealing and limiting their functions. The main goals of MOF research are to create high-porosity MOFs and develop more efficient activation techniques to preserve and access their pore space. This paper examines the porosity tunable mixed and hybrid MOF, pore architecture, physical and chemical properties of tunable MOF, pore conditions, market size of MOF, and the latest development of MOFs as precursors for the synthesis of different nanostructures and their potential uses. Full article

Advanced Oxidation Processes (AOPs) offer promising methods for disinfection by generating radical species like hydroxyl radicals, superoxide anion radicals, and hydroxy peroxyl, which can induce oxidative stress and deactivate bacterial cells. Photocatalysis, a subset of AOPs, activates a semiconductor using specific electromagnetic wavelengths. A novel material, Cu/Cu₂O/CuO nanoparticles (NPs), was synthesized via a laser ablation protocol (using a 1064 nm wavelength laser with water as a solvent, with energy ranges of 25, 50, and 80 mJ for 10 min). The target was sintered from 100 °C to 800 °C at rates of 1.6, 1.1, and 1 °C/min. The composite phases of Cu, CuO, and Cu₂O showed enhanced photocatalytic activity under visible-light excitation at 368 nm. The size of Cu/Cu₂O/CuO NPs facilitates penetration into microorganisms, thereby improving the disinfection effect. This study contributes to synthesizing mixed copper oxides and exploring their activation as photocatalysts for cleaner surfaces. The electronic and electrochemical properties have potential applications in other fields, such as capacitor materials. The laser ablation method allowed for modification of the band gap absorption and enhancement of the catalytic properties in Cu/Cu₂O/CuO NPs compared to precursors. The disinfection of E. coli with Cu/Cu₂O/CuO systems serves as a case study demonstrating the methodology’s versatility for various applications, including disinfection against different microorganisms, both Gram-positive and Gram-negative. Full article

We explore security aspects of a new computing paradigm that combines novel memristors and traditional Complimentary Metal Oxide Semiconductor (CMOS) to construct a highly efficient analog and/or digital fabric that is especially well-suited to Machine Learning (ML) inference processors for Radio Frequency (RF) signals. Analog and/or hybrid hardware designed for such application areas follows different constraints from that of traditional CMOS. This paradigm shift allows for enhanced capabilities but also introduces novel attack surfaces. Memristors have different properties than traditional CMOS which can potentially be exploited by attackers. In addition, the mixed signal approximate computing model has different vulnerabilities than traditional digital implementations. However both the memristor and the ML computation can be leveraged to create security mechanisms and countermeasures ranging from lightweight cryptography, identifiers (e.g., Physically Unclonable Functions (PUFs), fingerprints, and watermarks), entropy sources, hardware obfuscation and leakage/attack detection methods. Three different threat models are proposed: (1) Supply Chain, (2) Physical Attacks, and (3) Remote Attacks. For each threat model, potential vulnerabilities and defenses are identified. This survey reviews a variety of recent work from the hardware and ML security literature and proposes open problems for both attack and defense. The survey emphasizes the growing area of RF signal analysis and identification in terms of commercial space, as well as military applications and threat models. We differ from other recent surveys that target ML, in general, neglecting RF applications. Full article

Interface termination bonding between metal oxide and metals is discussed from the viewpoint of thermodynamics. The method of interface termination prediction proposed by the authors for Al₂O₃–metal and ZnO–metal interfaces is extended to a general interface between metal-oxide and metals. The extension of the prediction method to the interface between metal oxides and elemental semiconductors is also discussed. Information on interface bonding was extracted by carefully examining the experimental results and first-principles calculations in the references. The extracted information on interface bonding from references is compared with the results obtained via the proposed prediction method. It is demonstrated that interface termination bonding can be predicted by extending the method to oxide–metal interfaces in general, when there is no interface reaction such as the reduction of oxide, oxidation of metal, or mixed oxide formation. The method uses only basic quantities of pure elements and the formation enthalpy of oxides. Therefore, it can be applied to most of the metals (including elemental semiconductors) in the periodic table and metal oxides with one stable valence. The method is implemented as a software, “InterChemBond”, and can be used free of charge. Full article

Since its invention in the 1960s, one of the most significant evolutions of metal-oxide semiconductor field effect transistors (MOSFETs) would be the 3D version that makes the semiconducting channel vertically wrapped by conformal gate electrodes, also recognized as FinFET. During recent decades, the width of fin (W_fin) and the neighboring gate oxide width (t_ox) in FinFETs has shrunk from about 150 nm to a few nanometers. However, both widths seem to have been leveling off in recent years, owing to the limitation of lithography precision. Here, we show that by adapting the Penn model and Maxwell–Garnett mixing formula for a dielectric constant (κ) calculation for nanolaminate structures, FinFETs with two- and three-stage κ-graded stacked combinations of gate dielectrics with SiO₂, Si₃N₄, Al₂O₃, HfO₂, La₂O₃, and TiO₂ perform better against the same structures with their single-layer dielectrics counterparts. Based on this, FinFETs simulated with κ-graded gate oxides achieved an off-state drain current (I_OFF) reduced down to 6.45 × 10⁻¹⁵ A for the Al₂O₃: TiO₂ combination and a gate leakage current (I_G) reaching down to 2.04 × 10⁻¹¹ A for the Al₂O₃: HfO₂: La₂O₃ combination. While our findings push the individual dielectric laminates to the sub 1 nm limit, the effects of dielectric permittivity matching and κ-grading for gate oxides remain to have the potential to shed light on the next generation of nanoelectronics for higher integration and lower power consumption opportunities. Full article

Iron oxides (hematite, Fe₂O₃, and magnetite, Fe₃O₄), previously used as electron mediators in the galvanic system with zero-valent aluminum (ZVAl), have been shown to recover Au upon cementation in Au–Cu ammoniacal thiosulfate media selectively, and this warrants further investigation. This research is focused on investigating the role of the semiconductive properties of metal oxides by performing a cementation experiment by mixing 0.15 g of electron mediators (Fe₃O₄, Fe₂O₃, TiO₂ (anatase and rutile)) and 0.15 g of zero-valent aluminum powder as an electron donor in various electrochemical experiments. The results revealed that upon the cementation experiment, synthetic Fe₂O₃ and Fe₃O₄ were consistently able to selectively recover Au at around 90% and Cu at around 20%. Compared to activated carbon (AC), TiO₂, in anatase and rutile forms, obtained selective recovery of gold, but the recovery was utterly insignificant compared to that of iron oxides, obtaining an average of 93% Au and 63% Cu recovery. The electrochemical and surface analysis supports the results obtained upon the cementation process, where TiO₂, upon cyclic voltammetry (CV), obtained two reduction peaks centered at −1.0 V and −0.5 V assigned to reducing Au and Cu ions, respectively. Furthermore, various electrochemical impedance spectroscopic analyses revealed that the flat band potential obtained in the Mott–Schottky plot is around −1.0 V and −0.2 V for iron oxides and titanium oxides, respectively, suggesting that the electrons travel from semiconductor interface to electrolyte interface, and electrons are accessible only to Au ions in the electrolyte interface (reduction band edge around −1.0 V). The determination of this selective cementation mechanism is one of a kind. It has been proposed that the semiconductive properties of Fe₂O₃, Fe₃O₄, and, by configuring their relative energy band diagram, the travel of electrons from the iron oxide–electrolyte interface facilitate the selective cementation towards Au(S₂O₃)₂³⁺ ions in gold–copper ammoniacal thiosulfate solutions. Full article