Sulfide corrosion of Cu is rapid, and hydrogen atoms produced by its cathodic half-reaction could adsorb on the Cu surface and diffuse into the Cu, potentially leading to hydrogen embrittlement. However, in solutions with low concentrations of SH-, absorption of hydrogen into Cu is not observed by ex situ hydrogen analysis, although it is unclear whether this is due to the lack of absorption, the outgassing of hydrogen from the Cu before it can be measured, or another mitigation mechanism. Herein, hydrogen uptake into Cu and the development of Cu2S layers during corrosion by SH- were studied by in situ neutron reflectometry and electrochemical impedance spectroscopy. The method relies on a 4-nm Ti layer beneath 50 nm of Cu to trap hydrogen that may penetrate the Cu. Additionally, elastic recoil detection analysis and Rutherford backscattering spectrometry were used to measure hydrogen. While no increase in hydrogen was detected in either the Ti or Cu layers, a higher concentration of hydrogen was observed in the outer Cu2S layer (2560 ppm) than in the underlying Cu (244 ppm), demonstrating that bisulfide-driven corrosion does not lead to hydrogen absorption into the Cu. These results have implications for deep geological repositories utilizing Cu corrosion barriers. Hydrogen uptake into Cu and the development of Cu2S layers during SH- corrosionCu2S film was initially observed to be compact before it transitioned to porousTransition from compact to porous occurs likely via small cracks in the Cu2S layerNo hydrogen absorption into either the Ti or Cu layers was detectedThe presence of hydrogen in the outer Cu2S layer (average 3.2Cu:S ratio) was detected

Sodium (Na) metal batteries (NMBs) offer great potential for high-energy-density storage applications. However, their practical use remains constrained by persistent challenges such as Na dendrite growth and interfacial instability. In this work, we design and fabricate a dual-metal-sites crosslinked polymer interface on Na metal anodes, which synergistically integrates sodiophilic sites, rapid interfacial kinetics, and enhanced mechanical crosslinking. This nanoscale hybrid interface features a tunable composition, optimized sodiophilicity, and exceptional mechanical stiffness, effectively suppressing dendrite propagation and stabilizing Na deposition. Electrochemical evaluations demonstrate that the dual-metal-sites hybrid interface enables unprecedented cycling stability under high-capacity operation. Complementary insights from electro-chemo-mechanical DFT modeling and mechanistic experiments reveal that the dual-metal synergy decouples ionic transport from mechanical degradation, facilitating homogeneous Na+ flux and adaptive SEI reconfiguration. By combining sodiophilic functionality with robust polymer-metal coordination, this work establishes a universal design strategy for durable, dendrite-free metal anodes, advancing the development of next-generation energy storage technologies.

TRi-structural ISOtropic (TRISO) fuel is a new-generation nuclear fuel with a multilayer coating system for long-term containment. However, the effect of ionizing radiation from radioactive decay on the coupled multilayer system under deep geological repository (DGR) conditions remains insufficiently understood. In this work, we studied the effects of DGR-relevant alpha- and gamma-radiation conditions on pyrolytic carbon (PyC) and silicon carbide (SiC) layers. Raman spectroscopy showed that alpha irradiation caused significant structural changes in both PyC and SiC. Irradiation at 100°C to simulate annealing did not cause noticeable recovery in either material. Nanoindentation results showed increased hardness and elastic modulus after alpha irradiation, whereas gamma irradiation resulted in a softer mechanical response without major chemical changes. The results indicate that the changes may increase the susceptibility of the coating layers to cracking or fracture and are therefore important for understanding the safe long-term containment of TRISO fuel under repository conditions.

ABSTRACT Nanophotonic lenses are transformative optical elements for nanoscale light manipulation and miniaturized optical systems. For a given material platform, the finite thickness of a planar metalens limits the phase and group‐delay response available for simultaneously achieving high numerical aperture, broad bandwidth, and high focusing efficiency. This Review examines the transition from planar to three‐dimensional (3D) nanophotonic lenses for imaging and how added degrees of freedom expand the available optical design space. State‐of‐the‐art fabrication methods, with emphasis on two‐photon lithography, are discussed together with computational design strategies including topology optimization, evolutionary algorithms, and machine learning. Recent demonstrations show that this enlarged design space can support broadband focusing, aberration correction, depth‐of‐field control, and multichannel imaging. Key challenges in scalable fabrication, material development, and large‐scale inverse design are summarized as a roadmap for future 3D nanophotonic lenses.

Neutron scattering methods, particularly neutron reflectometry, and ion scattering techniques, such as Rutherford backscattering spectrometry (RBS), medium-energy ion scattering (MEIS), and other accelerator-based methods such as nuclear reaction profiling (NRP), can provide high-resolution depth profiles of solid surfaces and near-surface buried regions that are difficult or impossible to obtain by other means. Applying these analytical methods to a material in situ, while it is undergoing corrosion processes, could yield valuable information about the composition and structure of the interfacial region, including corrosion product layers and the subsurface of the specimen. However, neither neutron beams nor ion beams are compatible with aqueous electrochemical environments without special innovations. Neutrons pass easily through substantial amounts of many types of materials, but the hydrogen present in the water of an aqueous electrolyte solution is a strong incoherent scatterer of neutrons, so the neutron beam used for in situ neutron reflectometry studies of corrosion processes must not pass through water on its way to probing the electrode/electrolyte interface. To overcome this inconvenience, we deposit a thin film of the material of interest in the corrosion experiments on a Si single-crystal wafer, which we mount on an electrochemical cell such that the specimen is in contact with the electrolyte solution while the neutrons access the specimen and proceed to the detector by passing through the Si substrate (a path length of about 10 cm through the solid) without ever entering the water. Likewise, ions are easily deflected by collisions with gaseous atoms and molecules in the atmosphere, so ion beam techniques are used within a chamber under ultra-high vacuum. Moreover, trying to penetrate an aqueous solution with an ion beam to allow the ions to interact with a corroding surface is unfeasible. Nevertheless, we have been developing an approach to enable in situ corrosion studies using ion beams by constructing an hermetically sealed electrochemical cell that can be filled with aqueous electrolyte at atmospheric pressure, then installed in the UHV chamber of an ion accelerator to enable ion beam analyses. The difficulties with delivering the ions to the corroding surface to probe its composition and structure while it is immersed in an aqueous electrolyte are overcome by depositing a thin film of the material of interest on a 100-nm-thick SiN substrate that can act as a “window” for the ions. The ions then access the specimen from the back side, and those that eventually contribute to the analysis also return through the SiN window, exiting the specimen toward the detector after interacting with the material of interest. This allows the analysis to proceed without the ions having to pass through the aqueous solution in contact with the specimen. This talk will describe the apparatus and approaches, as well as some of the experimental complications encountered, such as water radiolysis and high background signals, illustrated with examples from the ion beam measurements we have made on titanium in aqueous NaCl solutions under both open-circuit and polarized conditions and the neutron reflectivity measurements we have made in conjunction with electrochemical impedance spectroscopy to detect and quantify hydrogen absorption on corroding Ti, Zr, and Cu.

Nuclear power is a clean, safe, and economical energy source and after hydrothermal-powered sources, it is the second largest contributor to low-emitting electricity. However, the continuous usage of nuclear power entails the obligation to deal with the long-term management of used nuclear fuel. To do so, Canada plans to use a deep geological repository (DGR) system that will be built approximately 500-800 meters underground in Wabigoon Lake First Nation and the Township of Ignace, Ontario. The DGR consists of corrosion-resistant used fuel containers (UFCs) and other barriers, and it is expected to provide safe and long-term containment of radioactive waste. However, it is essential to consider the eventual failure of the UFCs which can expose fuel to groundwater and pose potential risks. Most of the radionuclides within the used fuel are trapped inside the fuel matrix and the fuel dissolution rate in groundwater determines how fast they can be released into the environment. The containers are expected to remain intact for a long time and any potential breach is likely to occur after β- and γ-radiation have largely decayed. This makes α-radiation the dominant radiation source at the fuel surface and a primary focus. The α-irradiation can cause accumulated radiation-induced damage to the fuel matrix and a possible scenario in this case is the formation of soluble U VI . This can increase the fuel’s dissolution rate as U VI is more soluble than U V and U IV by several orders of magnitude. Therefore, it is necessary to understand the direct effects of high-energy α-particles on the surface of UO 2 -based fuels, as these interactions may influence the fuel dissolution rate. This study uses a novel approach to investigate the effects of α-particles on UO 2 -based fuels via in-situ α-irradiation-electrochemistry experiments. This approach enables studying the surface oxidation state of the fuel in a thin-layer configuration exposed to α-irradiation. The method utilizes UO 2 thin film samples and the Tandetron Accelerator’s Rutherford backscattering beamline to deliver the high-energy high-flux α-particles. To prepare UO 2 thin films, electrodeposition parameters were first optimized via comprehensive characterization of the films deposited on copper substrates to assess their morphology, elemental composition, phase, and crystal structure. Overall, it was found that using less-negative potentials and current densities is optimal for achieving stable films with smaller cracks, better adherence, and higher crystallinity after annealing. UO 2 thin films were then deposited on copper-coated SiN windows using optimized electrodeposition parameters, and the samples were subsequently integrated into a custom-designed in-situ cell for α-irradiation-electrochemistry experiments. Investigations of the effects of high-energy α-particles via in-situ α-irradiation-electrochemistry experiments are currently underway. The surface oxidation states of UO 2 films after α-irradiation will be studied and the effects of α-irradiation on dissolution rate, surface morphology, and phase structure of the UO 2 samples will be presented.

In-situ electrochemical measurements during ion beam analysis to determine electrochemical oxide growth mechanisms is challenging, due to the need for a liquid electrolyte solution to enable the oxide growth and a high vacuum for the beam path. Our specially designed in-situ electrochemical cell for Rutherford backscattering spectroscopy (RBS) uses a high-energy-ion-permeable 100-nm-thick SiN window that allows us to measure the time evolution of elemental depth profiles characteristic of titanium anodization. In-situ RBS results show a titanium anodization ratio significantly higher than that observed ex-situ (24.5 ± 0.6 Å∙Vˉ 1 ), as well as spontaneous TiO 2 film growth at the open circuit potential. The growth enhancement factor under α irradiation was determined to be 1 nm/(2.5 × 10 12 × α) (i.e., there was a direct linear correlation between α-particle exposure and increased oxide thickness). Direct and indirect α-radiation exposure measurements determined the enhanced titanium oxide thickness generated via radiation and radiolysis effects. The grain size within the irradiated TiO 2 film was significantly smaller (25 ± 5 nm) than the grain size of the unirradiated film (40 ± 10 nm). In-situ electrochemical impedance spectroscopy was conducted for the first time in the presence of α-radiation in solution, and five different regimes with characteristic open-circuit potential (OCP) changes were identified. An equivalent electrical circuit analysis suggests that the changes detected in the defect-related charge transfer and a decrease in the resistance of the growing titanium oxide are the main factors contributing to the enhanced growth. Our accurate quantification of these effects allows for reliable comparison of in-situ and ex-situ anodization experiments.

Microcracks and surface heterogeneity in solid-electrolyte interphase (SEI) induced by repeated plating/stripping of lithium (Li) metal exacerbate SEI fracture propagation and dendrite growth, which lead to unsatisfactory Coulombic efficiency and limited cycle life of Li metal anode. In this study, the hybrid artificial interfaces with controlled organic-inorganic ratios are designed and deep insight into their impacts on the electro-chemo-mechanical properties is obtained. The organic-inorganic ratios in the hybrid interfaces influence the mechanical properties, lithiophilicity, and diffusion kinetics of the interfaces, which in turn affect the nucleation, early growth, and repeated deposition/dissolution behavior of Li. It is found that increasing the inorganic ratio in the hybrid interface can realize significantly enhanced electrochemical performances. This work answers a key question for hybrid interfaces: should organic-rich or inorganic-rich be preferred in the hybrid interface? It is believed that this work will guide the future design of hybrid interfaces for Li metal anode and open up opportunities for the realization of next-generation Li metal batteries. Through adjusting the organic-inorganic ratio inside the hybrid interfaces, the mechanical toughness, lithiophilicity, and diffusion kinetics of the hybrid interfaces can be precisely tuned, which thereby influences the nucleation, early growth behavior, and final bulk deposition morphology of Li. image

Persistent luminescence (PersL) materials are excellent candidates in the dynamic and multimodal anticounterfeiting field. Compared to commercially available micrometer-sized PersL phosphors, nanosized PersL materials could blend more easily with solvents and allow printing patterns with fine details. MgGeO3 is one of the frequently employed lattice hosts for PersL phosphors. It can accommodate divalent ions such as Mn2+ to produce deep-red PersL. To date, the only reported method of synthesizing nanosized Mn-doped MgGeO3 (MGO:Mn) is the sol-gel method. The synthesis product has a wide particle size distribution and suffers severe aggregation. In this work, MGO:Mn nanorods are synthesized, for the first time, with a uniformly distributed morphology. These nanorods exhibit more intense and longer-lasting PersL. A detailed comparative study between the MGO:Mn nanorods developed in this work and the MGO:Mn particles prepared by the sol-gel method is performed to identify the origin of the improved PersL property. We also demonstrate that the afterglow duration of the MGO:Mn nanorods can be further modulated by adding co-dopants such as Yb-,(3+) Eu3+, and Li+. The Yb3+ dopant also introduces a second PersL emission band in the near-infrared region of similar to 1000 nm. Using a combination of these MGO-based PersL nanorods, dynamic and multimodal anticounterfeiting can be achieved.

Na metal batteries (NMBs) are attracting increasing attention because of their high energy density. However, the widespread application of NMBs is hindered by the growth of Na dendrites and interface instability. The design of artificial solid electrolyte interphase (SEI) with tuned chemical/electrochemical/mechanical properties is the key to achieving high-performance NMBs. This work develops a metal-doped nanoscale polymeric film with tunable composition, sodiophilic sites and improved stiffness. The incorporation of metal crosslinkers in the polymer chains results in exceptional electrochemical stability for Na metal anodes, leading to a significantly prolonged lifespan even at high current densities, which is at the top of the reported literature. The mechanical properties measurements and electro-chemo-mechanical phase-field model are performed to interpret the impact of the ionic transportation capability (decoupled mechanical) and mechanic property in the metal-doped polymer interface. In addition, this approach provides a promising strategy for the rational design of electrode interfaces, providing enhanced mechanical stability and improved sodiophilicity, which can open up opportunities for the fabrication of next-generation energy storage.

We have formed SixGe1-x-ySny compounds on Si substrates by ion implantation and annealing and investigated their concentration profiles, crystallization, and optical properties. Ge and Sn ions were implanted in the range (2.5-10) x 10(16) Ge/cm(2) at 65 keV, and (1.0-4.0) x 10(16) Sn/cm(2) at 100 keV, resulting in a peak implant dose at a depth of 50 nm for both species. Epitaxially regrown SixGe1-x-ySny layers (110 nm thick) were produced with Ge and Sn contents that allowed bandgap tuning in the (0.88-1.1) eV range. Shifts in photoelectron binding energies (Si 2p, Ge 3d, and Sn 3d) were consistent with ternary compound formation. Sn segregation was observed for annealing temperatures >= 600 degrees C. A significant increase in the optical absorption coefficient (x10(4) cm(-1) for lambda = (800-1700) nm) was observed for SiGe, SiSn, and SiGeSn alloys, with SiGeSn having coefficients several orders of magnitude higher than for Si. Contributions of segregated Sn to these properties were observed. Metastable SixGe1-x-ySny layers were achieved, which may point to a promising route to mitigate Sn incorporation challenges for near-infrared detectors.

Metal anodes are considered the holy grail for next‐generation batteries because of their high gravimetric/volumetric specific capacity and low electrochemical potential. However, several unsolved challenges have impeded their practical applications, such as dendrite growth, interfacial side reactions, dead layer formation, and volume change. An electrochemically, chemically, and mechanically stable artificial solid electrolyte interphase is key to addressing the aforementioned issue with metal anodes. This study demonstrates a new concept of organic and inorganic hybrid interfaces for both Li‐ and Na‐metal anodes. Through tailoring the compositions of the hybrid interfaces, a nanoalloy structure to nano‐laminated structure is realized. As a result, the nanoalloy interface (1Al 2 O 3 –1alucone or 2Al 2 O 3 –2alucone) presents the most stable electrochemical performances for both Li‐and Na‐metal anodes. The optimized thicknesses required for the nanoalloy interfaces for Li‐ and Na‐metal anodes are different. A cohesive zone model is applied to interpret the underlying mechanism. Furthermore, the influence of the mechanical stabilities of the different interfaces on the electrochemical performances is investigated experimentally and theoretically. This approach provides a fundamental understanding and establishes the bridge between mechanical properties and electrochemical performance for alkali‐metal anodes.

Dye-dye conjugates have attracted significant interest for their utility in applications such as bioimaging, theranostics, and light-harvesting. Many classes of organic dyes have been employed in this regard; however, building blocks don't typically extend beyond small chromophores. This can lead to minor changes to the optoelectronic properties of the original dye. The exploration of dye-dye structures is impeded by long synthetic routes, incompatible synthetic conditions, or a mismatch of the desired properties. Here, we present the first-of-their-kind dye-dye conjugates of boron difluoride complexes of formazanate and dipyrromethene ligands. These conjugates exhibit dual photoluminescence bands that reach the near-infrared spectral region and implicate anti-Kasha processes. Cyclic voltammetry experiments revealed the generation of polyanionic species that can reversibly tolerate the uptake of up to 6 electrons. Ultimately, we demonstrate that BF2 formazanates can serve as a synthetically accessible platform to build upon new classes of dye-dye conjugates.

The few nanometres of titanium oxide present on titanium and Ti alloy surfaces are responsible for protecting the underlying metal from oxidation and enabling its use in many high-performance applications. The oxide provides a hard, uniform, and thermodynamically stable protective coating on an otherwise soft and very reactive metal. Because of its passivating oxide film, titanium has found uses in biomedical implants, aerospace engineering, corrosive industrial piping, and other areas where high strength and low weight are required. Our project is aimed at understanding the atomistic mechanisms of TiO 2 formation and growth. We have taken several different approaches to investigate the details of this process. In one approach, the electrochemical oxidation mechanism of titanium at applied potentials between 0 and 10 V vs the saturated calomel reference electrode (SCE) was examined for ultra-thin Ti films sputtered onto Si(001) substrates and exposed in-situ to H 2 18 O, and then anodized in D 2 16 O. The effects of this isotopic labeling procedure were studied using medium energy ion scattering (MEIS) and nuclear reaction profiling (NRP). Both MEIS and NRP results are consistent in showing that the titanium oxide layer is composed of two distinct regions (Ti 16 O 2 /Ti 18 O 2 /Ti/Si) for the entire range of the formation voltages (0–10 V vs SCE). The oxygen component of the outermost region consists entirely of 16 O, and the 18 O region is always adjacent to the Ti metal. No Ti or 18 O loss into the electrolyte solution during anodization was detected. The oxide thickened linearly as a function of potential in the 0–10 V range vs SCE, with experimental anodization ratio of 24.5±0.6 Å V −1 . Mott–Schottky (MS) analyses showed positive slopes, indicating formation of an n -type TiO 2 semiconductor, with O vacancies (or Ti interstitials) as major charge carriers in the 0–10 V range. Charge carrier densities, N D = (0.8-5.0)×10 21 cm −3 were calculated from Mott–Schottky analysis and were well within the range of results reported in the literature. We observed a decrease in the charge carrier densities above ∼4 V vs SCE, that can be connected to defect annihilation or minor modification in the structure (electrostatic annealing) of the growing TiO 2 film. In a second approach, we are using Rutherford backscattering spectrometry (RBS) for elemental depth profiling during oxide growth to determine oxidation rates and the role of the anodization potential on the Ti oxide layer structure and morphology. RBS is a powerful ion beam-based analytical tool used to determine thickness at the nanometer scale and elemental depth distribution, making it an excellent choice for studying the thin oxide on titanium. A difficulty with using RBS for such studies has been that RBS must function under ultra-high vacuum, and this has made it incompatible with performing aqueous electrochemistry; therefore, RBS had to be performed as an ex situ analysis, like MEIS and NRP. We are overcoming this limitation by using a specially designed in-situ cell with an ion-permeable silicon nitride window to provide a barrier between the ultra-high vacuum (UHV) required to perform RBS and the aqueous electrolyte solution required for anodization. In this cell, the thin silicon nitride window is coated with titanium and functions as the working electrode when exposed to the aqueous electrolyte solution. RBS measurements are taken as the titanium metal is anodized to titanium oxide. RBS is then performed during in-situ anodization, to obtain information about the growth mechanism of titanium oxide. Our initial in-situ RBS results show a significant increase in the oxidation rate of titanium compared to equivalent ex-situ measurements, and we also observe spontaneous TiO 2 film growth without applying an anodic polarization. These effects are likely generated by strongly oxidizing water radiolysis products (e.g., H 2 O 2 or ·OH) formed by the action of high-energy He + ions interacting with the electrolyte solution. This paper discusses our experimental methods and presents an overview of the results and conclusions of this work.

Inorganic persistent luminescence (PersL) nanoparticles (NPs) emitting at the deep-red and near-infrared (NIR) are promising candidates for applications in the biomedical field, such as optical imaging, sensing and therapy. The emission wavelength is closely related to the identity of the light activators (i.e. metal ion dopant), and the local environment they occupy in the host crystal lattice. In this paper, PersL nanoparticles with dual emission bands based on MgGeO3 was investigated. These nanoparticles exhibit one emission band at the deep-red region when doped with Mn2+. Introducing Yb3+ as a second dopant enables a deep-red-to-NIR energy transfer, producing dual-emission at both deep-red and NIR. The NIR emission can be further enhanced by the addition of Li+. A detailed spectroscopy study is performed to investigate the local structure around the light activators Mn2+ and Yb3+, and how it is influenced by the Li+ co-dopant. We found that adding the Yb3+ and Li+ changes the preferred site of occupancy for Mn2+, and when Mn2+ is shifted to a site that emits deep-red less efficiently, it acts as an electron trap to extend the PersL of the NIR-II emission. The mechanism for the deep-red-to-NIR energy transfer is proposed.

One concern regarding the used nuclear fuel containers proposed for use in a Canadian deep geological repository (DGR) is the possibility that a small amount of hydrogen might be absorbed into their copper coating, potentially altering its mechanical properties. Reported herein is a study of hydrogen absorption into 50 nm of copper, coated on 4 nm of Ti using in situ neutron reflectometry (NR) and electrochemical impedance spectroscopy (EIS). NR results show that hydrogen is absorbed when the copper is cathodically polarized below the threshold for the hydrogen evolution reaction (HER), but that the hydrogen concentrates in the underlying titanium layer rather than concentrating in the copper coating. The hydrogen concentration in titanium rapidly rose when the HER was initiated and was observed to reach a steady state at TiH1.5. Over the course of 55h of cathodic polarization, the concentration of hydrogen in the copper remained below the NR detection limit (2 at %). The portion of hydrogen atoms produced that diffused through the copper layer was initially 3.2%, suggesting a possible upper limit for hydrogen uptake by the copper coating of the UFC, although definitive conclusions can only be drawn from studies on 3 mm copper-coated steel samples.

Ion implantation has played a significant role in semiconductor device fabrication and is growing in significance in the fabrication of Si photonic devices. In this paper, recent progress in the growth and characterization of Si and Ge quantum dots (QDs) for photonic light-emitting devices is reviewed, with a focus on ion implantation as a synthetic tool. Light emissions from Si and Ge QDs are compared with emissions from other optically active centers, such as defects in silicon oxide and other thin film materials, as well as rare-earth light emitters. Detection of light in silicon photonics is performed via the integration of germanium and other elements into detector structures, which can also be achieved by ion implantation. Novel techniques to grow SiGe- and SiGeSn-on-Si structure are described along with their application as detectors for operation in the short-wave infrared range.

The electrochemical oxidation mechanism of titanium between 0 and 10 V vs saturated calomel reference electrode (SCE) was examined for ultra-thin Ti films sputtered onto Si(001) substrates and exposed in-situ to (H2O)-O-18, and then anodized in (D2O)-O-16. The effects of this isotopic labeling procedure were studied using medium energy ion scattering (MEIS) and nuclear reaction profiling (NRP). Both MEIS and NRP results are consistent in showing that the titanium oxide layer is composed of two distinct regions, (TiO2)-O-16/(TiO2)-O-18/Ti/Si(001) for the entire range of the formation voltages (0-10 V vs SCE). The outermost region consists entirely of O-16, and the O-18 region is always adjacent to the Ti metal. The two distinct structures observed can be consistent with both the point defect model (PDM) or high-field model (HFM), assuming the mobility of titanium cations is much higher compared to the mobility of oxygen ions. No Ti or O-18 loss into the electrolyte during anodization is detected. Linear growth rate is observed in 0-10 V range vs SCE with experimental anodization ratio of 24.5 +/- 0.6 angstrom V-1. Mott-Schottky (MS) analyses show positive slopes, indicating formation of an n-type TiO2 semiconductor, with O vacancies (or Ti interstitials) as major charge carriers in the 0-10 V range. Charge carrier densities, N-D = (0.8-5.0)x10(21) cm(-3) were calculated from Mott-Schottky analysis and were well within the range of results reported in the literature. We observe derease in the charge carrier densities above similar to 4 V vs SCE, that can be connected to defects annihilation or minor modification in the structure of the growing TiO2 film.

Low energy electron diffraction (LEED) peak intensities were measured to estimate surface Debye temperature for epitaxially-grown silicon thin films and for bulk Si (001). Rutherford backscattering spectroscopy (RBS, random and channeling modes) and positron annihilation spectroscopy (PAS) were used to quantify defect density and distribution in the near-surface layers. The surface Debye temperature of bulk Si (001), and 1.0 mu m, and 0.6 mu m Si on sapphire were measured to be 333 K, 299 K, and 260 K, respectively. RBS and PAS showed that the defect concentration was highest near the film/substrate interface, presumably due to the lattice mismatch, and decreased toward the top surface. The thicker film presented fewer defects in the surface and near-surface layers. We showed that a larger concentration of defects Nd in Si epitaxial films correlates with a lower surface Debye temperature following the empirical relation theta D = (365 +/- 14) - (8.1 +/- 1.5) x 10-13 Nd for our set of samples. Our study suggests the further development of LEED to estimate near-surface defect concentrations.

Alkali metals are regarded as the most promising candidates for advanced anode for the next-generation batteries due to their high specific capacity, low electrochemical potential, and lightweight. However, critical problems of the alkali metal anodes, especially dendrite formation and interface stabilization, remain challenging to overcome. The solid electrolyte interphase (SEI) is a key factor affecting Li and Na deposition behavior and electrochemical performances. Herein, a facile and universal approach is successfully developed to fabricate ionic conductive interfaces for Li and Na metal anodes by modified atomic layer deposition (ALD). In this process, the Li metal (or Na metal) plays the role of Li (or Na) source without any additional Li (or Na) precursor during ALD. Moreover, the key questions about the influence of ALD deposition temperature on the compositions and structure of the coatings are addressed. The optimized ionic conductive coatings have significantly improved the electrochemical performances. In addition, the electrochemical phase-field model is performed to prove that the ionic conductive coating is very effective in promoting uniform electrodeposition. This approach is universal and can be potentially applied to other different metal anodes. At the same time, it can be extended to other types of coatings or other deposition techniques.