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A detailed analysis of the N(1s) and C(1s) X-Ray Photoelectron Spectroscopy (XPS) is made, where the measured XPS is compared with theoretical Sudden Approximation (SA) intensities and theoretical XPS Binding Energies (BEs). There is remarkably good agreement between the theoretical predictions and the measured XPS; in particular, the different full width at half maximum values for the C(1s) and N(1s) BEs are explained in terms of unresolved C(1s) BEs for the different C atoms in pyridine. This work demonstrates that the combination of theory and XPS measurements can extract analysis of the XPS relevant to the molecular electronic structure. The theory used is based on fully relativistic self-consistent field solutions of the Dirac–Coulomb Hamiltonian, and the SA is used to determine relative XPS intensities. [ABSTRACT FROM AUTHOR]

This study presents a novel methodology for the separation of quartz and feldspar under neutral and weakly alkaline conditions. Ethyl-bis(dodecyl dimethyl ammonium bromide) (Gemini) is introduced as a new collector in the flotation process, combined with sodium oleate (NaOL) to enhance separation efficiency. The investigation focuses on the adsorption mechanism of these combined collectors on mineral surfaces. While the individual collectors, Gemini and NaOL, were ineffective in differentiating between quartz and feldspar, their combination resulted in significantly improved separation outcomes. Flotation tests indicated that at a pulp pH of 7, with Gemini and NaOL at concentrations of 12 × 10−5 mol l−1 and molar ratios of 1:1 and 1:2, the flotation recovery of quartz was 46.51% and 40.57% higher than that of potassium feldspar, respectively. Zeta potential measurements, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy analyses, and molecular dynamics simulations demonstrate that the Gemini collector predominantly influences the flotation performance of quartz and feldspar. NaOL molecules do not directly adsorb onto the quartz surface; instead, they co-adsorb via electrostatic interactions with Gemini, which minimally affects the interaction dynamics. In contrast, NaOL preferentially adsorbs onto the aluminum, silicon, and other reactive sites on the feldspar surface through its –COO functional group, leading to competitive adsorption with Gemini and consequently diminishing Gemini's effectiveness on feldspar. This study elucidates the selective separation mechanism of quartz and feldspar using Gemini and NaOL and aims to provide insights into employing combined collectors in diverse separation scenarios to enhance quartz quality. [ABSTRACT FROM AUTHOR]

The morphology, crystallinity, and photoconductive properties of gallium nitride films grown by pulsed chemical vapor deposition on p-type Si(100) with and without ammonia (NH3) pretreatment are investigated. Ammonia pretreatments were performed at 525 °C and 800 °C, which resulted in GaN film thicknesses of 80 and 140 nm, respectively. An amorphous film of GaN is obtained without pretreatment and a polycrystalline GaN film with pretreatment. X-ray photoelectron spectroscopy showed that the pretreatment results in a 1–2 nm bilayer consisting of SiNx and SiOxNy at the GaN/Si interface. Photoconductive measurements show the 525 °C pretreated GaN film has a responsivity of 72 mA W−1 and a rise time of 0.37 ms, whereas the GaN film with an 800 °C pretreatment has a responsivity of 246 mA W−1 and a rise time of 1.7 ms. Moreover, the photocurrent of the 525 °C pretreated device exhibits superlinear power dependence with a power coefficient of 1.74, whereas the 800 °C pretreated device exhibits sublinear power dependence with a power coefficient of 0.58. The superlinear power dependence of the photoresponse of the 525 °C pretreated film is attributed to the presence of fast and slow recombination centers. [ABSTRACT FROM AUTHOR]

Black titania nanotubes possess an extraordinary surface functionality while having a high absorbance in the visible light range. In this study, a low-temperature manufacturing approach for dark titania nanotubes is presented: low-energy low-fluence carbon ion implantation. It allows a local chemical reduction, preserves the amorphous structure and induces oxygen vacancies, leading to high electrical conductivity. The material's modification is unveiled on microscopic and macroscopic scales: electrical characteristics are recorded on the nanometer scale using tunneling atomic force microscopy and overall with two-point measurements. The depth-resolved atomic composition is assessed via elastic recoil detection analysis, while optical and x-ray photoelectron spectroscopy elucidate the global chemical binding situation and bandgap shifts. This extensive analysis supports the concept of percolated carbon paths that vertically span the nanotubes and provide a substantial contribution to the enhanced conductivity. In combination with the utilization of implantation masks, a versatile route for a targeted and localized material's manipulation toward patterned dark amorphous titania nanotubes is demonstrated that gives rise to innovative materials and smart devices. [ABSTRACT FROM AUTHOR]

Recently, spin asymmetry in O 2p related deep valence states was evidenced in SrTiO3(001) [Popescu et al., Phys. Scr. 99(10), 105925 (2024)]. In this work, we report the detection of a much higher (about four times) spin asymmetry in SrTiO3(011) by spin resolved photoelectron spectroscopy, with samples characterized also by core level x-ray photoelectron spectroscopy and low energy electron diffraction. The explanation of a so important spin asymmetry is related to the partial neutralization of O2(4−) or SrTiO(4+) end layers. Missing electrons from O 2p states in the case of O2 terminations enable robust atomic spins, according to Hund's rule. The parallel analysis of core level shifts for surface atoms and the amplitude of spin asymmetry suggests that 50% of the oxygens from the surface SrO layer of SrTiO3(001) have a 2p5 configuration with an unpaired electron (the rest are in a 2p6 configuration), while in the case of O2 terminated SrTiO3(011), about 50% of surface oxygens have a 2p5 configuration and 50% of surface oxygens are neutral (2p4), yielding a net charge per O2 surface unit cell of (−1) instead of (−4). The magnetization is oriented along the rows formed by the (4 × 1) reconstruction in the 0 1 ̄ 1 in-plane direction. [ABSTRACT FROM AUTHOR]

Long afterglow is a fascinating luminescence phenomenon exhibited by certain storage phosphors that emit visible light after being stimulated by ultraviolet rays. Strontium magnesium silicate phosphors doped with europium and dysprosium (Sr2MgSi2O7:Eu2+, Dy3+) have garnered attention in recent years. Enhancing the afterglow performance of these phosphors remains a significant challenge. In this study, we investigate the enhancement of afterglow performance in Sr2MgSi2O7:Eu2+, Dy3+ phosphors prepared via a sol–gel auto-combustion method using commercial silica (CS) and lab-made nanosilica (NS). Our results reveal that the afterglow performance of the NS-based phosphor is significantly improved, glowing with optimal intensity for a prolonged period compared to the CS-based phosphor. Time-resolved photoluminescence studies show that the average lifetime of the NS-based phosphor is enhanced tenfold compared to the CS-based phosphor, attributed to the improved crystallinity of the NS-based phosphor. Photoluminescence studies indicate that both phosphors exhibit comparable performance. Thermoluminescence studies suggest that the presence of multiple trap levels with varying trap depths in the NS-based phosphor allows it to exhibit extended afterglow emission than the CS-based phosphor. Structural, morphological, and optical properties of the phosphors were analyzed using x-ray diffraction, Fourier transform infrared, x-ray photoelectron spectroscopy, field emission scanning electron microscopy, and UV–vis techniques. The underlying mechanism of the afterglow is explained in detail. The prepared phosphor was used to create flexible and transparent labels with silicone rubber, which can serve as indicators during dark hours. [ABSTRACT FROM AUTHOR]

The advancement of neuromorphic computing in resistive random-access memory (RRAM) is crucial for the rapid expansion of artificial intelligence. Conventional metal oxide-based RRAM faces challenges in mimicking synaptic activity, leading to the exploration of new resistive switching (RS) materials. This study introduces a ZnO@β-SiC composite-based RRAM device that exhibits biological synapse-like functionality. The device shows self-compliance and forming-free RS at ∼0.8 V, where it also mimics synaptic responses such as potentiation, depression, and paired-pulse facilitation at low voltage stimuli (∼0.6 V, 40 ms) with learning and forgetting behavior. Moreover, the synaptic plasticity is analyzed through spike rate dependent plasticity, spike number dependent plasticity, and spike time dependent plasticity. Further, the transition from short-term plasticity to long-term plasticity is observed under more training pulses and lower interval stimuli. The observed RS mechanism and synaptic functionalities are explained by the electric field-driven formation and dissolution of conducting filaments of oxygen vacancies. The chemical properties and local electronic structure have been examined by x-ray photoelectron spectroscopy and x-ray absorption spectroscopy. To elucidate the atomistic memristive behavior and the contribution of different electrical parameters in RRAM, detailed conductive atomic-force microscopy and impedance analysis have been carried out. [ABSTRACT FROM AUTHOR]

Despite the many advantages afforded to the investigation of complex compositional systems by combinatorial sputtering, the application of this synthesis technique is hindered by high-throughput characterization bottlenecks. The recent application of translatable compositional and magnetic characterization techniques, such as precision Wavelength Dispersive X-ray Fluorescence (WDXRF) and Magneto-Optic Kerr Effect (MOKE), are enabling for full wafer mapping of film chemistry, magnetic moment, and coercivity, although under-applied. An example system that stands to benefit from the application of combinatorial sputtering and high-throughput characterization is lightly nitrided FexVyNz, which, among other doped FeN materials, is a candidate rare earth-free permanent magnet for electric motor and read/write head applications. Within this report, a combinatorial sputtering and characterization procedure, which leverages high-throughput WDXRF and MOKE mapping, is utilized to investigate the effects of V composition on the room temperature ferromagnetic properties of FexVyNz. Observations made using WDXRF and MOKE mapping are shown to closely agree with vibrating sample magnetometry and x-ray photoelectron spectroscopy measurements made on cleaved regions of interest from the parent wafer. It is observed that the inclusion of V deleteriously affects the saturated moment of FeN, resulting in complete macroscopic reduction at 18 at. %. A maximum film coercivity of 165 Oe is observed at 10 at. % V, likely contributed to by crystallographic texture due to processing, followed by a complete reduction along with the saturated moment. These observations support the high-throughput characterization approaches of WDXRF and MOKE to combinatorial synthesis workflows. [ABSTRACT FROM AUTHOR]