Quantifying the CaO and CaF₂ content of industrial ladle furnace slag with optical emissions measured through the casting spout

Abstract CaO and CaF₂ are important slag constituents and additive materials in secondary metallurgy. Optimization of the quantity of these compounds has a key role in adjusting the slag chemistry for optimal refining properties. In this study, the CaO and CaF₂ content of the slag has been analyzed with optical emissions from an industrial ladle furnace measured through the casting spout. Molecular optical emissions from CaO and CaF were observed directly from the molten bath and the arc, whereas atomic emission lines from the slag components were detected in the arc spectra. Optical emissions from CaO, CaF, and atomic calcium lines have been correlated with the CaO and CaF₂ content of the slag. The CaO and CaF₂ content of the slag could be evaluated from the spectra ranging from 10 to 41 min before the X-ray fluorescence (XRF) analysis was finished. The mean differences between the OES and XRF analysis were 0.59 % and 0.61 % for CaF₂, and 2.19 % and 0.67 % for CaO when using the spectra from the molten bath and the arc, respectively. The method has the potential to work as an in situ online measurement system due to real-time data acquisition and fast computation times

Ab initio study of hydrogen sensing in Pd and Pt functionalized GaN [0 0 0 1] nanowires

Abstract Using density functional theory based simulations, the adsorption of hydrogen on GaN nanowires with [0 0 0 1] orientation is studied with Pt and Pd functionalization. The adsorption energies show that both Pt and Pd prefer to attach to a top site above the Ga atom in the nanowire. In the pristine GaN, hydrogen attach as a molecule, while in the presence of Pt and Pd, it dissociates into atoms and adsorb through a chemical bonding. Change in Ga-N bond lengths are observed with hydrogen adsorption on the surface of the nanowire and the resultant strain as well as the charge transfer between atoms can be used as entities to understand the detection mechanism. From the electronic structure analysis, it is revealed that both Pt and Pd can be used to tune the band gap and are favorable adsorbates to enhance the hydrogen sensing properties of GaN nanowires. Pt turns out to be a more efficient adsorbate for hydrogen detection due to the lowered adsorption energies, compact Pt-H bond length and enhanced surface charge reconstruction

15th international conference on electronic spectroscopy and structure:book of abstracts

Welcome to ICESS 15th Welcome to the 15th ICESS conference! Finally, after five years of waiting it is our pleasure to welcome you - the whole international community – to Oulu, Finland. The scientific program built in collaboration with international advisory board (IAB) covers widely the areas of research and surely engages plenty of discussions and ideas for future collaborations. Great thanks for participating and making the event possible! Let us all make the event pleasant respecting the diversity and committing to strengthening the international community of ICESS. Welcome to Oulu! ICESS local committee: Marko Huttula, chair Minna Patanen, program committee Samuli Urpelainen, Satu Ojala, local organizatio

Efficient neutralization of core ionized species in an aqueous environment

Abstract Core ionization dynamics of argon–water heteroclusters ArM[H₂O]N are investigated using a site and process selective experimental scheme combining 3 keV electron irradiation with Auger electron–ion–ion multi-coincidence detection. The formation of Ar 2p⁻¹ vacancies followed by non-radiative decay to intermediate one-site doubly ionized states Ar²⁺(3p⁻²)−ArM−1[H₂O]N and subsequent redistribution of charge to the cluster environment are monitored. At low argon concentrations the emission of an [H₂O]n′H⁺/[H₂O]n′′H⁺ ion pair is the dominant outcome, implying on high efficiency of charge transfer to the water network. Increasing the condensation fraction of argon in the mixed clusters and/or to pure argon clusters is reflected as a growing yield of Arm′+/Arm′′+ ion pairs, providing a fingerprint of the precursor heterocluster beam composition. The coincident Auger electron spectra, resolved with better than 1 eV resolution, show only subtle differences and thereby reflect the local nature of the initial Auger decay step. The results lead to better understanding of inner shell ionization processes in heterogeneous clusters and in aqueous environments in general

Optical emission spectroscopy as a tool for process control of steelmaking burners

Abstract In contemporary steelmaking, burners are widely used for heating slabs in walking beam and annealing furnaces, heat-up of empty ladles, flame cutting of steel, as well as providing additional energy in electric arc furnaces. To facilitate the future of carbon-neutral steelmaking, a transition from natural gas-based burners toward hydrogen-based burners is essential to reduce the CO2 emissions associated with the burners. In addition to this transition, it is important also to optimize the burner practices that are used today, since the transition will take its time. To this end, CO2 reductions could also be realized with process control aiming toward more efficient use of energy and gas resources. This study presents how optical emission spectroscopy could be used for on-line monitoring and process control of the burner flame. A case study of oxy-fuel cutting is presented, where optical emissions from H2O, C2, FeO, Na, and K together with thermal radiation were observed. The flame’s properties, such as temperature and radiative heat transfer, identification of the flame species and impurities, and detection of rapid changes in the flame are analyzed from the OES data

Adsorption of CO₂ on the ω-Fe (0001) surface:insights from density functional theory

Abstract The stabilization of a hexagonal phase known as the ω-phase in steel has recently been identified. The presence of C in steel samples is found to be helping the formation of this otherwise meta stable phase. This indicates that the probability of degradation of the surface is high in steel samples containing the ω-phase, through surface adsorption. Here we calculate the adsorption process of CO₂ on the ω-Fe(0001) surface, for different sites and find that it strongly adsorbs horizontally with a bent configuration. The adsorption is characterized by significant charge transfer from the surface Fe atoms to the CO₂ molecule, and structural modification of the molecule is occurring. The density of states calculations indicate that hybridization and subsequent charge transfer is probable between the d orbitals of Fe and p orbitals of CO₂, resulting in strong chemisorption, that further leads to spontaneous dissociation of the molecule

Orienting spins in dually doped monolayer MoS₂:from one-sided to double-sided doping

Abstract Electron spins of the doped monolayer MoS₂ were aligned by placing two magnetic impurities at sulfur vacancies, both on the same side and different sides of the slab. Origins of the calculated magnetisms are beyond most conventional physical models, yet interactions of single-molecule magnets are tentatively proposed

One-pot hydrothermal synthesis of BiVO₄ microspheres with mixed crystal phase and Sm³⁺-doped BiVO₄ for enhanced photocatalytic activity

Abstract The BiVO₄ microspheres and Sm³⁺-doped BiVO₄ polygons were prepared via a facile hydrothermal method by means of K₆V₁₀O₂₈·9H₂O as a novel vanadium source. Optimized temperature and pH value of prepared BiVO₄ were obtained. The polycrystalline BiVO₄ microspheres prepared at T = 140 °C, pH 4, demonstrates the best photocatalytic activities for degrading dyes under UV radiation. This is resulted due to transfers of photogenerated electrons from tetragonal to monoclinic phases. In contrast to the undoped BiVO₄, the photocatalytic activity of Sm³⁺-doped BiVO₄ polygons is drastically enhanced not only under UV radiation but also under visible light radiation. The optimized Sm content was found to be 10 %. Enhanced efficiency with the doped sample is attributed to the dopants’ role in blocking recombination of photogenerated electron–hole pairs. This work offers a simple route to obtain mixed phase BiVO₄ and provide an effective way to achieve higher photocatalytic activity by doping the Sm³⁺ in the semiconductor catalysts

Surface plasmon-driven photocatalytic activity of Ni@NiO/NiCO₃ core–shell nanostructures

Abstract Ni@NiO/NiCO3 core–shell nanostructures have been investigated for surface plasmon driven photocatalytic solar H₂ generation without any co-catalyst. Huge variation in the photocatalytic activity has been observed in the pristine vs. post-vacuum annealed samples with the maximum H₂ yield (∼110 μmol g⁻¹ h⁻¹) for the vacuum annealed sample (N70–100/2 h) compared to ∼92 μmol g⁻¹ h⁻¹ for the pristine (N70) photocatalyst. Thorough structural (X-ray diffraction) and spectroscopic (X-ray photoelectron spectroscopy and transmission electron microscopy coupled electron energy loss spectroscopy) investigations reveal the core Ni nanoparticle decorated with the shell, a composite of crystalline NiO and amorphous NiCO₃. Significant visible light absorption at ∼475 nm in the UV-vis region along with the absence of a peak/edge corresponding to NiO suggest the role of surface plasmons in the observed catalytic activity. As per the proposed mechanism, amorphous NiCO₃ in the shell has been suggested to serve as the dielectric medium/interface, which enhances the surface plasmon resonance and boosts the HER activity

Harnessing photo/electro-catalytic activity via nano-junctions in ternary nanocomposites for clean energy

Abstract Though solar energy availability is predicted for centuries, the diurnal and asymmetrical nature of the sun across the globe presents significant challenges in terms of harvesting sunlight. Photo/electro-catalysis, currently believed to be the bottleneck, promises a potential solution to these challenges along with a green and sustainable environment. This review aims to provide the current highlights on the application of inorganic-semiconductor-based ternary nanocomposites for H₂ production and pollutant removal. Various engineering strategies employing integration of 2D materials, 1D nanorods, and/or 0D nanoparticles with inorganic semiconductors to create multiple nano-junctions have been developed for the excellent photocatalytic activity. Following a succinct description of the latest progress in photocatalysts, a discussion on the importance of ternary electrocatalysts in the field of next-generation supercapacitors has been included. Finally, the authors’ perspectives are considered briefly, including future developments and critical technical challenges in the ever-growing field of photo/electro-catalysis