Hydrogen Incorporation Research Articles

Intra-grain variability of hydrogen and trace elements in rutile

Rutile is a commonly used petrogenetic indicator mineral to determine metamorphic temperatures, ages, host−/source lithologies, geochemical reservoirs, and subduction conditions. However, intra grain variabilities of trace elements in rutile are rarely considered. We performed trace element and hydrogen mapping of rutile to assess zoning and diffusion in natural rutile from various lithologies. Trace element and hydrogen show distinct zoning patterns, with mostly regular zoning in rutile from pegmatites and low-T hydrothermal clefts, and typically irregular zoning in rutile from high-P veins and metamorphic rocks. Whereas no clear patterns of trace element correlations can be identified, hydrogen, tri-, tetra- and pentavalent cations can show the same zoning patterns within single rutile grains, despite different substitution mechanisms. This indicates that hydrogen and trace element incorporation is externally controlled by availability and diffusivity of hydrogen and trace elements within the rock matrix, as well as rutile growth rates. H2O mapping reveals that hydrogen is retained in rutile at temperatures of up to ~650 °C. Coupled substitution of hydrogen with divalent and trivalent cations requires coupled diffusion processes for charge balance if hydrogen is diffusively re-equilibrated. Slow diffusion rates and thus relatively high temperatures for diffusive closure in rutile lead to retention of primary hydrogen and trace element zoning. At high-T conditions of >650 °C, diffusive re-equilibration of all trace elements can be observed. Complex zoning patterns of Zr in rutile show that Zr incorporation into rutile is not purely temperature dependent. In this study, Zirconium-undersaturation can lead to inaccurate Zr-in-rutile temperatures of up to ~35 °C difference from peak formation temperatures within single rutile grains and might be a useful tool to evaluate rutile growth conditions. Niobium and Ta are highly zoned in rutile, leading to extremely variable Nb/Ta ratios within single rutile grains that cannot be reconstructed from single spot analyses. Overall, mapping offers a novel and promising tool to understanding trace element behavior in rutile.

Comprehensive Screening of Plasma-Facing Materials for Nuclear Fusion

Plasma-facing materials (PFMs) represent one of the most significant challenges for the design of future nuclear fusion reactors. Inside the reactor, the divertor will experience the harshest material environment: intense bombardment of neutrons and plasma particles coupled with extremely large and intermittent heat fluxes. The material designated to cover this role in ITER is tungsten. While no other materials have shown the potential to match the properties of tungsten, many drawbacks associated with its application remain, including cracking and erosion induced by a low recrystallization temperature combined with a high ductile-brittle transition temperature and neutron-initiated embrittlement; surface morphology changes (helium bubbles and fuzz layer) due to plasma-tungsten interaction with subsequent risk of spontaneous material melting and delamination; and low oxidation resistance in the case of air contamination. Exploring alternatives to tungsten requires the design of a multivariable optimization problem. This work aims to produce a structured and comprehensive material screening of PFM candidates based on known inorganic materials. The method applied in this study to identify the most promising PFM candidates combines peer-reviewed data present in the PAULING FILE database and first-principles density-function theory calculations focusing on two key PFM defects—namely, the sputtering of surface atoms and the incorporation of interstitial hydrogen, respectively characterized by the surface binding energy and the interstitial formation energy. The crystal structures and their related properties, extracted from the PAULING FILE, are ranked according to the heat-balance equation of a PFM subjected to the heat loads in the divertor region of an ITER-like tokamak. The materials satisfying the requirements are critically compared with the state-of-the-art in plasma-facing materials research and in studies of refractory materials exposed to high temperatures, plasma, and neutron bombardment. This comparison assesses their thermo-mechanical properties under such conditions, identifying a subset of promising materials for first-principles electronic structure calculations. Most previously known and extensively studied PFMs, such as tungsten, molybdenum, and carbon-based materials, are captured by this screening process, confirming its reliability. Additionally, less familiar refractory materials suggest performance that calls for further investigations. Published by the American Physical Society 2024

Experimental Investigation and Chemical Kinetics Analysis of Carbon Dioxide Inhibition on Hydrogen-Enriched Liquefied Petroleum Gas (LPG) Explosions

The utilization of hydrogen-enriched liquefied petroleum gas (LPG) is an effective means of reducing carbon emissions, but the special physical and chemical properties of hydrogen have raised concerns among the public. To delve into the intricate chemical kinetic mechanisms governing the inhibitory effect of CO2 on the explosion of hydrogen-enriched LPG, this study systematically investigated the influence of varying CO2 concentrations (3%, 6%, and 9%) on the explosion characteristics of hydrogen-enriched LPG (hydrogen ratio ranging from 0 to 0.5) within a 20 L spherical explosion chamber. Subsequently, a chemical kinetic analysis was conducted, focusing on the explosion reaction dynamics of the H2/LPG/CO2/Air mixture, encompassing temperature sensitivity assessments and the production rates of key free radicals. The findings reveal that although hydrogen incorporation does not significantly alter the maximum explosion pressure of LPG, it markedly accelerates the explosion reaction rate, posing a challenge for CO2 in effectively inhibiting the explosion of hydrogen-enriched LPG. CO2 functions as a stabilizing third body within the reaction system, diminishing the collision frequency among free radicals, hydrogen molecules, hydrocarbon molecules, and oxygen molecules, thereby slowing down the reaction rate. As the proportion of hydrogen increases, the concentration of ·H radicals, known for their high reactivity, escalates, rapidly completing the propagation phase of the chain reaction and intensifying the overall generation rates of critical free radicals, including ·H, ·O, and ·OH. Notably, the key reaction H+O2⇋O+OH, which governs the reaction temperature, undergoes significant enhancement, further accelerating the explosion reaction rate and ultimately diminishing the inhibitory efficacy of CO2 against the hydrogenated LPG explosion. Furthermore, as the amount of hydrogen added increases, hydrogen’s competitiveness for oxygen within the reaction system markedly improves, attenuating the oxidation of hydrocarbons. Concurrently, the alkane recombination reaction, exemplified by C3H6+CH3(+M)⇋sC4H9(+M), is strengthened. These insights provide valuable understanding of the complex interactions and mechanisms during the explosion of hydrogen-enriched LPG in the presence of CO2, with implications for the safe application of hydrogen-enriched LPG.

A Highly Efficient Catalytic Co-Combustion of Aromatic and Oxygenated Volatile Organic Compounds (VOCs) via H2-Driven Onsite Heating

Catalytic combustion, a highly efficient technique for reducing volatile organic compounds (VOCs), is the focus of this study. We investigate the improved catalytic efficiency of the physical mixing of nanosized Pt and atomically dispersed Co, supported on Al2O3 catalysts (Pt-Co)/Al2O3 (PM) for the catalytic combustion of VOCs. The catalyst efficiency is evaluated for the hydrogen-assisted catalytic oxidation of various VOCs, including aromatic and oxygenated VOCs such as benzene, toluene, methanol, and formic acid. Our study aims to understand the impact of hydrogen incorporation on the combustion process of various VOCs. The findings of this work underscore the potential of hydrogen-assisted catalytic ignition, which can achieve ignition at ambient temperature, a significant departure from conventional electric heating that typically requires additional energy to raise the temperature. Various characterization techniques, such as BET, STEM, and XRD, are employed to assess the structure–activity relationship of the catalyst. The optimal hydrogen concentration for complete VOC conversion is 3%. Notably, even at a lower hydrogen concentration of 2%, benzene and methanol reach an ideal ignition temperature of over 500 °C when introduced into the physically mixed catalyst. This study highlights the significant potential of hydrogen-assisted catalytic combustion, inspiring further research and offering a promising method to reduce VOCs effectively.

Hydrogen activation and surface exchange over La0.8Sr0.2Ga0.8Mg0.2O3-z

Hydrogen mass-transfer between molecular hydrogen and La0.8Sr0.2Ga0.8Mg0.2O3-z (LSGM) has been studied by means of hydrogen isotope exchange with gas phase equilibration. The measurements were carried out within a temperature range of 300–700 °C, with molecular hydrogen pressures of 100, 150 and 200 Pa. It was found that LSGM is capable of consuming hydrogen from the gas phase. The relative number of hydrogen atoms in the LSGM structure varied between 1 and 4 mol.%. The kinetics of hydrogen isotope redistribution revealed that the mass-transfer mechanism between molecular hydrogen in the gas phase and LSGM includes at least three steps. The first two relate to dissociative and associative/molecular adsorption of molecular hydrogen, while the third, identified as the rate-determining step in the exchange process, relates to hydrogen incorporation into LSGM structure. The kinetic and thermodynamic isotope effects of the exchange were estimated.

Influence of in-situ hydrogenation on photoelectrical properties of amorphous and nanocrystalline GeSn deposited by magnetron sputtering

This study investigates the fabrication of short-wavelength infrared (SWIR) photosensitive amorphous and nanocrystalline Ge1-xSnx:H thin films by magnetron sputtering from separate Ge and Sn targets using different Ar:H mixing ratios as working gas. Amorphous Ge1-xSnx:H films have been obtained on both c-Si and fused quartz substrates at ambient temperature, while dynamic nanocrystallization occurs in-situ when the substrate temperature during deposition is raised to 200 °C. Fourier-transform infrared spectroscopy has shown the hydrogen incorporation by detecting an absorption line at 1873 cm-1, close to the value corresponding to Ge-H bonding, only in the room temperature amorphous films. Based on that, we infer that the hydrogen concentration is very low in the films deposited at high temperature. The higher concentration of hydrogen in the amorphous samples is associated with an increase of the absorption gap to 0.5eV compared to 0.3eV in the 200oC samples. In-situ (during deposition) and ex-situ (by subsequent rapid thermal annealing) nanocrystallization have been analyzed by high-resolution transmission electron microscopy, X-ray diffraction and micro-Raman spectroscopy. SWIR spectral photosensitivity up to 2.4µm was found to be more than two orders of magnitude improved in hydrogenated amorphous films with high hydrogen content, compared to the nanocrystalline ones that are weakly hydrogenated. These findings demonstrate the potential of hydrogenation to enhance the photoelectric properties of GeSn sputtering films for optoelectronic SWIR infrared applications.

Fluorescently probing anaerobic digester sludge: Measuring single-cell anabolic activity in methanogens (Methanosarcina and Methanothermobacter) with deuterium-labeled Raman analysis

This study addresses the challenge of obtaining in situ information on substrate utilization rates for individual microbial species in complex microbial communities such as anaerobic digester sludge. To overcome this hurdle, a novel approach combining doubly-labelled deuterium, fluorescence in situ hybridization (FISH) and Raman microspectroscopy was developed. The method enables quantitative determination of anabolic heavy hydrogen incorporation into FISH-targeted, exemplified by methanogenic cells from the genera Methanosarcina and Methanothermobacter.The deuterium incorporation rates ascertained by Raman red-shifting of C-Hx vibrational region to C-Dx vibrations, quantified through Raman peak area ratios, were compared for different carbon sources. Methanosarcina exhibited highest kinetic rates with acetate and propionate, while Methanothermobacter demonstrated faster incorporation under acetate and methanol supplementation.This groundbreaking study demonstrates the feasibility of obtaining quantitative metabolic rate information at a single-cell level using deuterium, FISH probes, and Raman microspectroscopy.

On the Topotactic Phase Transition Achieving Superconducting Infinite-Layer Nickelates.

Topotactic reduction is critical to a wealth of phase transitions of current interest, including synthesis of the superconducting nickelate Nd0.8Sr0.2NiO2, reduced from the initial Nd0.8Sr0.2NiO3/SrTiO3 heterostructure. Due to the highly sensitive and often damaging nature of the topotactic reduction, however, only a handful of research groups have been able to reproduce the superconductivity results. A series of in situ synchrotron-based investigations reveal that this is due to the necessary formation of an initial, ultrathin layer at the Nd0.8Sr0.2NiO3 surface that helps to mediate the introduction of hydrogen into the film such that apical oxygens are first removed from the Nd0.8Sr0.2NiO3 / SrTiO3 (001) interface and delivered into the reducing environment. This allows the square-planar / perovskite interface to stabilize and propagate from the bottom to the top of the film without the formation of interphase defects. Importantly, neither geometric rotations in the square planar structure nor significant incorporation of hydrogen within the films is detected, obviating its need for superconductivity. These findings unveil the structural basis underlying the transformation pathway and provide important guidance on achieving the superconducting phase in reduced nickelatesystems.

Extensive hydrogen incorporation is not necessary for superconductivity in topotactically reduced nickelates

A key open question in the study of layered superconducting nickelate films is the role that hydrogen incorporation into the lattice plays in the appearance of the superconducting state. Due to the challenges of stabilizing highly crystalline square planar nickelate films, films are prepared by the deposition of a more stable parent compound which is then transformed into the target phase via a topotactic reaction with a strongly reducing agent such as CaH2. Recent studies, both experimental and theoretical, have introduced the possibility that the incorporation of hydrogen from the reducing agent into the nickelate lattice may be critical for the superconductivity. In this work, we use secondary ion mass spectrometry to examine superconducting La1−xXxNiO2 / SrTiO3 (X = Ca and Sr) and Nd6Ni5O12 / NdGaO3 films, along with non-superconducting NdNiO2 / SrTiO3 and (Nd,Sr)NiO2 / SrTiO3. We find no evidence for extensive hydrogen incorporation across a broad range of samples, including both superconducting and non-superconducting films. Theoretical calculations indicate that hydrogen incorporation is broadly energetically unfavorable in these systems, supporting our conclusion that extensive hydrogen incorporation is not generally required to achieve a superconducting state in layered square-planar nickelates.

(Invited) An Interplay between Electronic and Ionic Processes in Oxide Resistive Switching Devices

Emerging memory devices play a major role in implementing artificial neural networks as basic types of neuromorphic hardware. They provide extra functionality to conventional CMOS technology, such as the ability to implement non-volatile memory within a nanoscale region on the chip. Among 2-terminal devices, the resistive switching random access memory (RRAM) devices are very promising for these applications. However, the mechanisms of resistance changes depend on the oxide and metal electrode material and are still debated. Under an applied stress bias, MIM devices experience changes in their resistance from relatively large, in the high resistance state (HRS), to relatively low, in the low resistance state (LRS). These effects have generally been attributed to defect generation and aggregation in the oxide and depend on the chemical nature of metal electrodes. Using multiscale modelling, we investigate the role of electron injection and hydrogen incorporation inside amorphous (a) oxide films of SiO2, HfO2, Al2O3 and at interfaces with Si and TiN electrodes in creation of new defects, oxide degradation, and resistance change. The initial models of a-SiO2, a-HfO2 and a-Al2O3 structures are created using classical force-fields and the LAMMPS package. The volume and geometry of all structures are fully optimized using density functional theory (DFT) implemented in the CP2K code with the range-separated hybrid PBE0-TC-LRC functional, as described in detail in [1]. The results demonstrate that hole injection into amorphous SiO2, HfO2 and Al2O3 leads to hole localization at low-coordinated O sites in the amorphous network [2]. Injected extra electrons localize in amorphous SiO2 and HfO2 in deep states about 3.0 eV below the mobility edge [2]. Trapping of up to two electrons at intrinsic sites results in weakening of Si-O and Hf-O bonds and emergence of efficient bond breaking pathways for producing neutral O vacancies and interstitial Oi 2- ions with low activation barriers [2]. These barriers as well as barriers for migration of the O2- ion (< 0.5 eV) are further reduced by bias application. Simulations of SiO2/TiN interfaces [3] explain how, as a result of electroforming, the system undergoes very significant structural changes with the oxide being significantly reduced, interface being oxidized, and part of the oxygen leaving the system. Creation of O vacancies facilitates trap-assisted tunnelling through oxide films and is responsible for oxide charging and leakage current. Hydrogen and metal incorporation from metal electrodes leads to creation of additional defects in the oxide. DFT calculations of the incorporation and diffusion of Ag in Ag/SiO2/Me (Me=W or Pt) RRAM devices [4] show how the interplay between Ag+ ion diffusion, electron injection and vacancy creation lead to the formation of Ag clusters and filaments. Atomistic simulations of defect creation in amorphous oxide films are combined with kinetic simulations of trap assisted tunnelling of electrons and ionic diffusion through oxide [5,6]. They provide the mechanisms and time evolution of oxide charging and degradation. These mechanisms are used to simulate the kinetics of dielectric breakdown in devices and explain the mechanisms of set and reset in RRAM devices.[1] A-M. El-Sayed et al., Phys, Rev. B89, 125201 (2014)[2] J. Strand et al., J. Phys.: Condens. Matter30,233001 (2018)[3] J. Cottom et al. ACS Appl. Mater. Interfaces 11, 36232 (2019)[4] K. Patel et al. Microel. Reliab. 98, 144 (2019)[5] A. Padovani et al., J. Appl. Phys. 121, 155101 (2017)[6] J. Strand et al. J. Appl. Phys. 131, 234501 (2022)

Hydrogen incorporation into butter improves its microbial and chemical stability, biogenic amine safety, quality attributes, and shelf-life

Butter is susceptible to chemical and biological degradation. Hydrogen (H2) and nitrogen (N2) gases and BHT were incorporated into the butter, packaged into polyethylene laminated aluminum bags, and stored at 4 °C for 90 days. The microbial counts, peroxide value (PV), titratable acidity (TA), acidity degree value (ADV), and conjugated dienes and trienes (CD and CT) were examined. The samples' color and biogenic amines, amino acids, and volatile profiles were analyzed. At the end of storage, microorganisms grew slower in the H2 samples than in the other groups. The highest values of fat deterioration were determined for the control, while the lowest values were for the H2- and BHT-incorporated samples. All biogenic amines (BAs) showed the highest values in the control, while the lowest ones were observed in the BHT samples, followed by H2 and N2. H2 incorporation into butter limited the spoilage microorganism growth, improved the color, restricted the formation of BAs (44–61%), increased the levels of some amino acids (Met and Lys), and didn't give an off-flavor. The physicochemical results showed that H2 extended the shelf life of butter by 30 days. H2 incorporation can help the dairy industry extend shelf life and maintain the product's quality and safety.

Inhibited hydrogen uptake in metasomatised cratonic eclogite

Water occurs in Earth’s interior mostly as trace hydroxyl in nominally anhydrous minerals. Clinopyroxene is known to be an important water carrier in the uppermost mantle, and eclogite, which forms a subordinate part of the cratonic lithosphere, contains some 50% of jadeite-rich clinopyroxene, making this potentially a significant H2O reservoir in the bulk lithospheric mantle. Mantle metasomatism, in particular by small-volume melts like kimberlite, is known to enrich the lithosphere in highly incompatible components, but its effect on H2O contents in cratonic eclogite remains unclear. We report H2O concentrations for clinopyroxene and garnet in eclogite and pyroxenite xenoliths from several African kimberlites, obtained by Fourier-Transform Infrared Spectroscopy (FTIR). Except one sample showing evidence for minor within-grain variability of H2O concentrations (< 15%), FTIR images demonstrate that H2O is homogeneously distributed in optically clear areas of clinopyroxene fragments mounted for this study. The samples were variably metasomatised by a kimberlite-like melt, as evidenced by elevated MgO contents and abundances of highly incompatible elements (e.g., Sr, Ce, Th). Although metasomatised eclogites and pyroxenites on average show higher H2O abundances than pristine ones, mantle metasomatism decreases the Al2O3 content in clinopyroxene, which is known to enhance hydrogen incorporation in this mineral. As a consequence, hydrogen incorporation is inhibited, and c(H2O) becomes increasingly decoupled from other highly incompatible components, such as LREE. Thus, eclogite – metasomatised or not - does not significantly contribute to the H2O inventory in the bulk cratonic mantle.

The role of hydrogen as long-duration energy storage and as an international energy carrier for electricity sector decarbonization

With countries and economies around the globe increasingly relying on non-dispatchable variable renewable energy (VRE), the need for effective energy storage and international carriers of low-carbon energy has intensified. This study delves into hydrogen’s prospective, multifaceted contribution to decarbonizing the electricity sector, with emphasis on its utilization as a scalable technology for long-duration energy storage and as an international energy carrier. Using Japan as a case study, based on its ambitious national hydrogen strategy and plans to import liquefied hydrogen as a low-carbon fuel source, we employ advanced models encompassing capacity expansion and hourly dispatch. We explore diverse policy scenarios to unravel the timing, quantity, and operational intricacies of hydrogen deployment within a power system. Our findings highlight the essential role of hydrogen in providing a reliable power supply by balancing mismatches in VRE generation and load over several weeks and months and reducing the costs of achieving a zero-emission power system. The study recommends prioritizing domestically produced hydrogen, leveraging renewables for cost reduction, and strategically employing imported hydrogen as a risk hedge against potential spikes in battery storage and renewable energy costs. Furthermore, the strategic incorporation of hydrogen mitigates system costs and enhances energy self-sufficiency, informing policy design and investment strategies aligned with the dynamic global energy landscape.

Hydrogenation of calcite and change in chemical bonding at high pressure: Diamond formation above 100 GPa

Synchrotron X-ray diffraction (XRD) and Raman spectroscopy in laser heated diamond anvil cells and first principles molecular dynamics (FPMD) calculations have been used to investigate the reactivity of calcite and molecular hydrogen (H2) at high pressures up to 120 GPa. We find that hydrogen reacts with calcite starting below 0.5 GPa at room temperature forming chemical bonds with carbon and oxygen. This results in the unit cell volume expansion; the hydrogenation level is much higher for powdered samples. Single-crystal XRD measurements at 8–24 GPa reveal the presence of previously reported III, IIIb, and VI calcite phases; some crystallites show up to 4% expansion, which is consistent with the incorporation of ≤ 1 hydrogen atom per formula unit. At 40–102 GPa XRD patterns of hydrogenated calcite demonstrate broadened features consistent with the calcite VI structure with incorporated hydrogen atoms. Above 80 GPa, the CO stretching mode of calcite splits suggesting a change in the coordination of CO bonds. Laser heating at 110 GPa results in the formation of CC bonds manifested in the crystallization of diamond recorded by in situ XRD at 300 K and 110 GPa and by Raman spectroscopy on recovered samples commenced with C13 calcite. We explored several theoretical models, which show that incorporation of atomic hydrogen results in local distortions of CO3 groups, formation of corner-shared CO polyhedra, and chemical bonding of H to C and O, which leads to the lattice expansion and vibrational features consistent with the experiments. The experimental and theoretical results support recent reports on tetrahedral C coordination in high-pressure carbonate glasses and suggest a possible source of the origin of ultradeep diamonds.

Influence of Hydrogen on the Failure Mechanism of Standard Duplex Stainless Steel X2CrNiMoN22-5-3 Exposed to Corrosion Fatigue

IIn a geothermal environment, cathodic protection is employed to improve resistance against corrosion fatigue. However, during the cathodic reactions under applied potential, hydrogen is generated and assimilated, leading to a reduced lifetime expectancy of high-alloyed steels. The corrosion fatigue mechanism of a standard duplex stainless steel X2CrNiMoN22-5-3 (1.4462) specimen loaded with hydrogen was studied in a corrosion chamber specifically designed for the purpose, surrounded by the electrolyte of the Northern German Basin at 369 K. The microstructural reactions resulting in hydrogen incorporation significantly decrease the number of cycles to failure of the specimen. This reduction is attributed to hydrogen enhancing crack propagation and causing early failure, primarily due to the deterioration of the mechanical properties of the ferritic phase rather than corrosion reactions or corrosive degradation.

Enhanced Management of Unified Energy Systems Using Hydrogen Fuel Cell Combined Heat and Power with a Carbon Trading Scheme Incentivizing Emissions Reduction

In the quest to achieve “double carbon” goals, the urgency to develop an efficient Integrated Energy System (IES) is paramount. This study introduces a novel approach to IES by refining the conventional Power-to-Gas (P2G) system. The inability of current P2G systems to operate independently has led to the incorporation of hydrogen fuel cells and the detailed investigation of P2G’s dual-phase operation, enhancing the integration of renewable energy sources. Additionally, this paper introduces a carbon trading mechanism with a refined penalty–reward scale and a detailed pricing tier for carbon emissions, compelling energy suppliers to reduce their carbon footprint, thereby accelerating the reduction in system-wide emissions. Furthermore, this research proposes a flexible adjustment mechanism for the heat-to-power ratio in cogeneration, significantly enhancing energy utilization efficiency and further promoting conservation and emission reductions. The proposed optimization model in this study focuses on minimizing the total costs, including those associated with carbon trading and renewable energy integration, within the combined P2G-Hydrogen Fuel Cell (HFC) cogeneration system. Employing a bacterial foraging optimization algorithm tailored to this model’s characteristics, the study establishes six operational modes for comparative analysis and validation. The results demonstrate a 19.1% reduction in total operating costs and a 22.2% decrease in carbon emissions, confirming the system’s efficacy, low carbon footprint, and economic viability.

The Effect of Implantoplasty on the Fatigue Behavior and Corrosion Resistance in Titanium Dental Implants.

Implantoplasty is a technique increasingly used to remove the biofilm that causes peri-implantitis on dental implants. This technique of mechanization of the titanium surface makes it possible to eliminate bacterial colonies, but it can generate variations in the properties of the implant. These variations, especially those in fatigue resistance and electrochemical corrosion behavior, have not been studied much. In this work, fatigue tests were performed on 60 dental implants without implantoplasty, namely 30 in air and 30 in Hank's solution at 37 °C, and 60 with implatoplasty, namely 30 in air and 30 in Hank's solution at 37 °C, using triaxial tension-compression and torsion stresses simulating human chewing. Mechanical tests were performed with a Bionix servo-hydraulic testing machine and fracture surfaces were studied by scanning electron microcopyElectrochemical corrosion tests were performed on 20 dental implants to determine the corrosion potentials and corrosion intensity for control implants and implantoplasty implants. Studies of titanium ion release to the physiological medium were carried out for each type of dental implants by Inductively Coupled-Plasma Mass Spectrometry at different immersion times at 37 °C. The results show a loss of fatigue caused by the implantoplasty of 30%, observing that the nucleation points of the cracks are in the areas of high deformation in the areas of the implant neck where the mechanization produced in the treatment of the implantoplasty causes an exaltation of fatigue cracks. It has been observed that tests performed in Hank's solution reduce the fatigue life due to the incorporation of hydrogen in the titanium causing the formation of hydrides that embrittle the dental implant. Likewise, the implantoplasty causes a reduction of the corrosion resistance with some pitting on the machined surface. Ion release analyses are slightly higher in the implantoplasted samples but do not show statistically significant differences. It has been observed that the physiological environment reduces the fatigue life of the implants due to the penetration of hydrogen into the titanium forming titanium hydrides which embrittle the implant. These results should be taken into account by clinicians to determine the convenience of performing a treatment such as implantoplasty that reduces the mechanical behavior and increases the chemical degradation of the titanium dental implant.

Hydrogen incorporation mechanism in the lower-mantle bridgmanite

Abstract Bridgmanite, the most abundant mineral in the lower mantle, can play an essential role in deep-Earth hydrogen storage and circulation processes. To better evaluate the hydrogen storage capacity and its substitution mechanism in bridgmanite occurring in nature, we have synthesized high-quality single-crystal bridgmanite with a composition of (Mg0.88Fe0.052+Fe0.053+Al0.03)(Si0.88Al0.11H0.01)O3 at nearly water-saturated environments relevant to topmost lower mantle pressure and temperature conditions. The crystallographic site position of hydrogen in the synthetic (Fe,Al)-bearing bridgmanite is evaluated by a time-of-flight single-crystal neutron diffraction scheme, together with supporting evidence from polarized infrared spectroscopy. Analysis of the results shows that the primary hydrogen site has an OH bond direction nearly parallel to the crystallographic b axis of the orthorhombic bridgmanite lattice, where hydrogen is located along the line between two oxygen anions to form a straight geometry of covalent and hydrogen bonds. Our modeled results show that hydrogen is incorporated into the crystal structure via coupled substitution of Al3+ and H+ simultaneously exchanging for Si4+, which does not require any cation vacancy. The concentration of hydrogen evaluated by secondary-ion mass spectrometry and neutron diffraction is ~0.1 wt% H2O and consistent with each other, showing that neutron diffraction can be an alternative quantitative means for the characterization of trace amounts of hydrogen and its site occupancy in nominally anhydrous minerals.

Impact of channel thickness on device scaling in vertical InGaZnO channel charge-trap memory transistors with ALD Al2O3 tunneling layer

This study investigates the impact of channel thickness (TCH) variation on memory performance and its physical origins in vertical channel charge trap memory (V-CTM) using InGaZnO (IGZO) channels for X–Y scaling. When the TCH decreased, the subthreshold slope (SS) increased from 0.21 to 0.30 V/dec, while the minimum program voltage decreased from 12 to 8 V, indicating a performance trade-off. The analysis of bulk trap density extracted by SS, density of states distribution, and x-ray photoelectron spectroscopy confirmed an increase in the number of trap states and hydrogen-related defects in the IGZO channel when a thin TCH is employed. As a result, it was expected that the barrier height at the active layer/TL would be lowered during program operations at relatively thin channel. However, the SS would also be degraded due to an increase in sub-gap states, such as OH- and VOH, induced by hydrogen incorporation. The V-CTM with an optimal TCH of 7 nm had a maximum memory window of 5.7 V. The program/erase states were maintained for 106 s before experiencing a 50 % charge loss, and 5-level memory states were verified to be available within a memory window of 3.2 V for 108 s with little degradation. It was noteworthy that the long-term reliability and multilevel implementation could be secured for the V-CTM with a TCH as thin as 7 nm, demonstrating the sound feasibility of its X–Y scaling. This work presents new key parameters and understanding of device integration issues for future 3D structured memory transistors, and aims to contribute to the advancement of memory technologies using oxide semiconductor channels.

Impact of hydrogen plasma treatment on fluorine-contained silicon nitride films

It has been suggested that the trap energy level in silicon nitride (SiN) films becomes shallow due to hydrogen and fluorine incorporation, which causes a charge migration in the MONOS memory cells and deteriorates the data retention characteristics. To solve these issues, we have proposed the hydrogen plasma treatment and demonstrated the reduction of the shallow trap density consequent to the removal of hydrogen from SiN films. In this study, the hydrogen plasma treatment is applied to the fluorine-contained SiN films. The results show that deepening of the trap energy level contributing to hole current, decreasing of the shallow trap density contributing to charging and the fluorine concentration near at the SiN surface. These results are regarded to be due to the removal of fluorine in the SiN film through the reaction with hydrogen radicals (H*) during the hydrogen plasma treatment.