Metallic Side Research Articles

Dual driven asymmetric electrolyte with gradient distributed UPy-CNTs for high-performance lithium metal batteries

Asymmetric electrolytes with both anode and cathode compatibility are promising candidates for high-energy–density batteries and high-safety lithium metal batteries (LMBs). However, the asymmetric electrolyte is still hindered by the complex multi-layer coating process, resulting in multiple internal interfaces of the electrolyte and poor battery performance. Herein, a one-step constructed asymmetric electrolyte with gradient distributions of 2‐ureido‐4[1H]-pyrimidinone functionalized carbon nanotubes (UPy-CNTs) is prepared via the dual driving forces of solvent evaporation and fluoropolymer migration. On the one hand, during the solvent evaporation process, based on the competitive effect between evaporation of solvent and diffusion of dispersions, the gradient distribution of asymmetric electrolyte can be constructed by enhancing evaporation and inhibiting uniform diffusion. On the other hand, due to the abundant hydrogen bonds between UPy and F, the gradient distribution of UPy-CNTs can be further promoted when the fluoropolymer spontaneously migrates to the surface. The gradient distribution of UPy-CNTs not only greatly increases Young’s modulus of the asymmetric electrolyte on the Li metal side, but also can adjust the Li+ solvation structure to form a LiF-rich solid electrolyte interface (SEI), thereby inhibiting the generation and growth of lithium dendrites. Because of the ingenious structure of the asymmetric electrolyte, the ionic conductivity is 0.226 mS cm−1 and the Li+ transferences number is 0.79. Prominently, Li||Li symmetric batteries can stably cycle for 2500 h at 0.1 mA cm−2 and 0.1 mAh cm−2. In addition, Li||LFP batteries can maintain a high specific capacity of 146 mAh g−1 after 200 cycles at 0.5C.

Atypical Attack of the Dissimilar Metal Welds of a Water–Water Energetic Reactor Nuclear Power Plant Secondary Circuit: Possible Mechanisms of Failure

ABSTRACTDissimilar metal welds are utilized in the energy industry to connect two materials with different material characteristics. In the case of nuclear power plants, the connected materials tend to be low‐alloyed steel and high‐alloyed material. Despite different material and corrosion properties, under the proper environmental conditions, the used construction materials and weld metals are protected either by a passive layer or by a high‐temperature oxide. Although dissimilar metal welds are used in both primary and secondary circuits, the most frequently documented damage is in the secondary circuit, where, in addition to material heterogeneities, local environmental heterogeneities may form. For dissimilar metal welds in WWER nuclear power plants, a water–water energetic reactor, a subtype of pressure water reactor, we note two main types of attack near the dissimilar fusion boundary: on the carbon steel side or on the high‐alloyed weld metal side (X10CrNiMoN16‐25‐6). The possible causes of the latter “atypical” corrosion attack are debated and can be generalized as a consequence of change of the grain boundary condition.

Synthesis and Doping of Alkali Metals on MOF-74 for CO2 and CH4 Pure and Binary Mixtures Adsorption

The emergence of the industrial revolution, marked by a global supply-demand network mostly dependent on fossil fuels, has resulted in the generation of carbon emissions. Metal-organic frameworks (MOFs) have materialized as a innovative category of adsorbents extensively studied by researchers on CO2 adsorption over recent years because of their significant adsorption capability. Amongst the different types of MOFs, Mg-MOF-74 is known for its open metal sides and its applicability of CO2 adsorption on flue gas. This work modifies Mg-MOF-74 by doping alkali metal cations (Na, Li, and K) to improve the efficacy of CO2 adsorption. The crystal structures of pure Mg-MOF-74 and Mg-MOF-74 doped with Na, Li, and K were compared by characterization using field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), and Brunauer-Emmet Teller (BET) surface area. A CO2 adsorption test determined the CO2 adsorption capacity of the modified Mg-MOF-74 at 70 oC temperature and up to 50 bar pressure. It was found that the BET specific surface area and the pore sizes of Mg-MOF-74 increased gradually by doping with Na, Li, and K by 7.07%, 11.75 %, and 14.91%. The CO2 and CH4 adsorption breakthrough experiment shows that the CO2 adsorption capacity has been increased from 8.9 wt.% to 11.68 wt.% under dynamic conditions.

The electrochemical performance deterioration mechanism of LiNi0.83Mn0.05Co0.12O2 in aqueous slurry and a mitigation strategy

Integrating high-nickel layered oxide cathodes with aqueous slurry electrode preparation routes holds the potential to simultaneously meet the demands for high energy density and low-cost production of lithium-ion batteries. However, the influence of dual exposure to air and liquid water as well as the heating treatment during aqueous slurry electrode processing on the high-nickel layered oxide electrode is yet to be understood. In this study, we systematically investigate the structural evolution and electrochemical behaviors when LiNi0.83Mn0.05Co0.12O2 (NMC83) is subjected to aqueous slurry processing. It was observed that the crystal structure near the surface of NMC83 is partially reconstructed to contain a mixture of rock-salt and layered phases when exposed to water, leading to the deteriorated rate capability of the NMC83 electrodes. This partial surface reconstruction layer completely converts into a pure rock-salt phase upon cycling, accompanied by the release of O2, Ni leaching, catalyzed decomposition of the electrolyte, and the formation of a thick cathode electrolyte interphase layer. The byproducts of the electrolyte and dissolved Ni could shuttle to the Li metal side, causing a crosstalk effect that results in a thick and unstable solid electrolyte interphase layer on the Li surface. These in combination severely undermined the cycling stability of the NMC83 electrodes obtained from the aqueous slurry. A mitigation strategy using molecular self-assembly technique was demonstrated to enhance the surface stability of water-treated NMC83. Our findings offer new insights for tailoring ambient environment stability and aqueous slurry processability for ultra-high nickel layered oxide and other water-sensitive cathode materials.

Metasurface Source Antenna Gain Improvement Using Simple Side Metal Structure.

As metasurfaces are in the spotlight, research is being conducted to incorporate them into transmitarray (TA) antennas. Among these, as an attempt to create a low-profile design, a patch antenna classified as low-gain can be utilized as an appropriate source antenna. However, for high efficiency of the TA, the gain of the source antenna must be fundamentally improved. For this, a simple side metal structure was applied to a metallic cross-type slot transmitarray. This acts as a resonant element and reflector by utilizing the electromagnetic wave radiated from the source antenna. The changes in the center frequency and gain due to the application of the side metal structure to the source antenna were analyzed. The gain of the source antenna was improved by a total of 4.63 dB. This is expected to be applied to create various source waves and to conduct future research on improving the gain in transmitarray antennas.

Heteroatom Immobilization Engineering toward High-Performance Metal Anodes.

Heteroatom immobilization engineering (HAIE) is becoming a forefront approach in materials science and engineering, focusing on the precise control and manipulation of atomic-level interactions within heterogeneous systems. HAIE has emerged as an efficient strategy to fabricate single-atom sites for enhancing the performance of metal-based batteries. Despite the significant progress achieved through HAIE in metal anodes for metal-based batteries, several critical challenges such as metal dendrites, side reactions, and sluggish reaction kinetics are still present. In this review, we delve into the fundamental principles underlying heteroatom immobilization engineering in metal anodes, aiming to elucidate its role in enhancing the electrochemical performance in batteries. We systematically investigate how HAIE facilitates uniform nucleation of metal in anodes, how HAIE inhibits side reactions at the metal anode-electrolyte interface, and the role of HAIE in promoting the desolvation of metal ions and accelerating reaction kinetics within metal-based batteries. Finally, we discuss various strategies for implementing HAIE in electrode materials, such as high-temperature pyrolysis, vacancy reduction, and molten-salt etching and anchoring. These strategies include selecting appropriate heteroatoms, optimizing immobilization methods, and constructing material architectures. They can be utilized to further refine the performance to enhance the capabilities of HAIE and facilitate its widespread application in next-generation metal-based battery technologies.

Electrical Resistivity Measurements of Surface-Coated Copper Foils.

Due to the direct contact between the probe and sample, the contact of the four-probe method is important for the structural integrity of the sample and the accuracy of electrical resistivity measurements, especially for surface-coated metal foils with multilayered structures. Here, we analyzed the accuracy and stability of four-probe method probing on different sides of copper (Cu) foils covered with graphene (Gr). Theoretical simulations showed similar potential distributions on the probe tip when probing on the Cu and Gr sides. The resistivity of the Gr/Cu foil was 2.31 ± 0.02 μΩ·cm when measured by probing on the Cu side, and 2.30 ± 0.10 μΩ·cm when measured by probing on the Gr side. The major difference in the mean deviation is attributed to surface damage. In addition, the method of probing on the Cu side was sensitive to the resistivity changes of Gr induced by polymers with a dielectric constant range of 2~12, which is consistent with the calculations based on the random phase approximation theory. Our results demonstrated that the probing position on the metal side in the four-probe method can effectively protect the structural integrity of the functional surface-coated layer and maintain the high sensitivity of the measurement, providing guidance for the resistivity measurements of other similarly heterogeneous materials.

Theoretical design of alkaline earthides M+(36 adz) Be− (M+ = V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) with excellent nonlinear optical response and ultraviolet transparency

A novel series of alkaline earthides containing eight complexes based upon 36adz complexant are designed by placing carefully transition metals (V–Zn) on inner side and alkaline earth metal outer side of the complexant i.e., M+(36adz) Be− (M+ = V, Cr, Mn, Fe, Co, Ni, Cu and Zn). All the designed compounds are electronically and thermodynamically stable as evaluated by their interaction energy and vertical ionization potential respectively. Moreover, the true nature of alkaline earthides is verified through NBOs and FMO study, showing negative charge and excess electrons on alkaline earth metal respectively. Furthermore, true alkaline earthides characteristics are evaluated graphically by spectra of partial density state (PDOS). The energy gap (HOMO -LUMO gap) is very small (ranging 2.95 eV–1.89 eV), when it is compared with pure cage 36adz HOMO-LUMO gap i.e., 8.50 eV. All the complexes show a very small value of transition energy ranging from 1.68eV to 0.89eV. Also, these possess higher hyper polarizability values up to 2.8 x 105au (for Co+(36adz) Be−). Furthermore, an increase in hyper polarizability was observed by applying external electric field on complexes. The remarkable increase of 100fold in hyper polarizability of Zn+(36adz) Be− complex is determined after application of external electric field i.e., from 1.7 x 104 au to 1.7 x 106 au when complex is subjected to external electric field of 0.001 au strength. So, when external electric field is applied on complexes it enhances the charge transfer, polarizability and hyper polarizability of complexes and proves to be effective for designing of true alkaline earthides with remarkable NLO response.

Induced-charge electrophoresis of a tilted metal nanowire near an insulating wall.

Electric fields are commonly used to control the orientation and motion of microscopic metal particles in aqueous suspensions. For example, metallodielectric Janus spheres are propelled by the induced-charge electro-osmotic flow occurring on their metallic side, the most common case in electrokinetics of exploiting symmetry breaking of surface properties for achieving net particle motion. In this work, we demonstrate that a homogeneous metal rod can translate parallel to a dielectric wall as a result of the hydrodynamic wall-particle interaction arising from the induced-charge electro-osmosis on the rod surface. The applied electric field could be either dc or low-frequency ac. The only requirement for a nonvanishing particle velocity is that the axis of the rod be inclined with respect to the wall, i.e., it cannot be neither parallel nor perpendicular. We show numerical results of the rod velocity as a function of rod orientation and distance to the wall. The maximum particle velocity is found for an orientation of between ∼30^{∘} and ∼50^{∘}, depending on the position and aspect ratio of the cylinder. Particle velocities of up to tens of µm/s are predicted for typical conditions in electrokinetic experiments.

Enhancing the Robustness of Hybrid Metal-Composite Connections Through 3D Printed Micro Penetrative Anchors

This work proposes a novel solution for manufacturing hybrid metal-composite joints, in which different pin shapes are evaluated for their capability to penetrate long carbon fiber epoxy composites successfully and for the mechanical behavior determined by each configuration. On the metal side, pins are manufactured by Laser Powder Bed Fusion (LPBF), downsizing the currently adopted solutions and, at the same time, developing new blocking features aimed at enhancing the mechanical properties of the joint. The different configurations were evaluated in two distinct experiments: the first to evaluate the induced defects in the composite substrate and the second to characterize the mechanical behavior of the joint. It emerges that smaller pins produce much less damage and misalignments in the composite structure with respect to the conventional pin solution, whereas the new “blocking features” configurations consistently increase maximum pullout load and energy with respect to the conventional pin solution, with the same level of fiber damage.

Bio-based innovations in cross-laminated timber (CLT) envelopes: A hygrothermal and life cycle analysis (LCA) study

The purpose of this study is to evaluate the performance of a Cross-Laminated Timber (CLT) building envelope that employs more bio-based materials, in terms of its hygrothermal behavior and environmental impact. The study involved the construction of four wall assemblies, comparing the effects of the installation of a self-adhesive air barrier on the CLT and the choice of insulation: bio-based wood fiber insulation or stone wool insulation. The walls were subjected to static and dynamic tests in a climate chamber, with temperature and relative humidity sensors installed across the walls. Additionally, the life cycle analysis (LCA) of the identical assemblies was calculated using the Ecoinvent 3.5 database.The findings of the study showed that the wood fiber insulation had a lower relative humidity and a temperature similar to the stone wool insulation. The air barrier reduced the transfer of moisture and increased the temperature across the wall. Furthermore, the wood fiber insulation acted as a moisture buffer, thereby delaying the migration of moisture through the envelope. Concerning the LCA, the metal siding had the highest global warming impact, followed by the insulation types. The wood fiber insulation had a similar impact to the stone wool insulation, except for eutrophication, where stone wool had a lower impact. The air barrier had a negligible impact compared to the rest of the envelope but prevented the CLT wall from being fully recycled. The biogenic carbon stored in the CLT and the wood fiber insulation reduced the global warming potential of the walls.

Laser welding of ultra-high strength steel rocket engine shell

The microstructure and mechanical properties of 30Cr3-30CrMnSiA ultra-high strength steel rocket engine shell welded joint were investigated in detail. The results indicated that the microstructure of the fusion zone was martensite of columnar and equiaxial due to the fast cooling rate of the laser welding. At the as-weld (AW) state, the average grain size of the 30Cr3 base metal was 4.63 μm, which was much smaller than that of the 30CrMnSiA base metal, which averaged 6.85 μm. After the post-weld heat treatment (PWHT), all the microstructures of the base metal, fusion zone and heat affected zone (HAZ) of 30Cr3 were tempered martensite. Meanwhile, at both AW and PWHT state, the tensile specimens of the welded joints of dissimilar materials were all fractured in the 30CrMnSiA base metal side at both 25 °C and 800 °C. After the PWHT, the tensile strength of 30CrMnSiA and 30Cr3 base metal at 25 °C were 1517.4 MPa and 1795.3 MPa, respectively. The welded joints of dissimilar materials by laser welding also showed excellent tensile properties at high temperature (800 °C), because of the small average grain size.

Coating of ThO2 (111) surface with two–dimensional sheets for potential corrosion protection

ThO2 is an important nuclear fuel that could be used in molten salt reactors, and its corrosion behaviors and anticorrosion mechanisms should be in–depth understood. More emerging two–dimensional (2D) sheets show potentially great corrosion resistance in metal corrosion due to their barrier properties and poor conductivity. In this work, first-principle calculations were performed to assess the potential ability of a series of 2D sheets for the corrosion protection of nuclear material ThO2. The strong binding interaction is found for two MXenes (Mo2C and Ti3C2 sheets) with ThO2 (111) surface revealed by their fairly low binding energy. The high binding strength of Mo2C and Ti3C2 sheets with ThO2 (111) surface originates from the remarkable charge redistribution around the interfaces. The coatings of the semiconducting 2D sheets on the ThO2 surface weaken the interaction with H2O. The one–side passivated MXenes can be efficiently anchored on the ThO2 surface through metal side, and the passivated side shows low adsorption affinity to H2O molecule. Our current work provides the basic understanding of the interaction between 2D nanosheets and ThO2 surfaces.

Microstructural evaluation and mechanical properties of WC-6%Co/AISI 1045 steel joints brazed by copper, brass, and Ag-based filler metals: Selection of the filler material

Due to the higher production cost of the monolithic carbide tools as well as their brittle nature, cemented carbides such as WC-Co are frequently joined to tool steel. To overcome the joining complications that arise due to notable differences in thermal expansions between the components and the poor wettability, various investigators have used copper-based and silver-based filler metals to dissimilarly braze the cemented carbides to steels. However, researchers do not agree about the selection of filler material. This research investigates the use of pure copper, brass, and silver-based filler metals to join the WC-Co cemented carbide to AISI 1045 steel. In this regard, microstructural features and mechanical properties including microhardness and shear strength were studied. The results indicate the formation of Cu(Fe,Co) solid solution and η carbides at the joint interfaces as well as the development of various precipitated phases in the joint area comprising Fe-Zn and Co-Zn intermetallic compounds. The reaction layers at both sides of the joints accompanied by cobalt-depleted zone on the hard metal side were observed. While using the α−β brass interlayer, the increase in hardness of the joint area through the presence of (Cu,Zn) solid solution compared to pure copper, the joint shear strength was enhanced from 161 to 173 MPa. On the other hand, the utilization of silver-based filler alloy with a distribution of hard copper-rich solid solution phase (182 HV) embedded in a silver-rich ductile matrix (88 HV), presenting a dispersion hardening effect, improved the shear strength of the joint to 203 MPa.

Improving interface bonding strength of laser-welded steel/CFRTP hybrid joint via bilayer silane film

The γ-aminopropyltrimethoxysilane (γ-APS) and γ-(2,3-epoxypropoxy) propyltrimethoxysilane (γ-GPS) single or bilayer silane film was produced to improve the tensile property of laser-welded 304 stainless steel/CFRTP joint in this work. The bonding mechanism at joint interface was investigated through experiments as well as density functional theory (DFT) calculation. Si-O-Fe covalent bonds were formed between steel and different silane films. Hydrogen bonds were induced at the interfaces of silane coating/polymer sides. The binding energy calculation results suggested that the binding between γ-APS silane coupling agent and steel was more stable than that of γ-GPS and steel. The binding energy of −3.37 eV between amino group in γ-APS and carbonyl group in CFRTP was greater than the binding energy of −4.84 eV between epoxy group in γ-GPS and amide group in CFRTP, which indicated stronger interaction was obtained between γ-GPS and polymer compared to the interaction between γ-APS and polymer. The bilayer silane coating could combine the dominant functional groups of silane monolayer film to obtain stable bonding on both metal side and CFRTP side. Moreover, compared with silane single film, longer silane oligomer molecular chain length was provided by bilayer silane film, resulting in more entanglement sites between silane film and CFRTP and the increased joint mechanical property. The steel/CFRTP hybrid joint reached maximum tensile shear strength of 17.2 MPa, which was further increased by 115.0% and 79.2% than that obtained by γ-APS and γ-GPS silane single coating, respectively.

Metal-ligand delocalization of iron and cobalt porphyrin complexes in aqueous solutions probed by soft X-ray absorption spectroscopy.

Metal-ligand delocalization of metal porphyrin complexes in aqueous solutions was investigated by analyzing the electronic structure of both the metal and ligand sides using soft X-ray absorption spectroscopy (XAS) at the metal L2,3-edges and nitrogen K-edge, respectively. In the N K-edge XAS spectra of the ligands, the energies of the CN π* peaks of cobalt protoporphyrin IX (CoPPIX) are higher than iron protoporphyrin IX (FePPIX). The energy difference between the two lowest peaks in the XAS spectrum of CoPPIX is also larger than that of FePPIX. Nitrogen K-edge inner-shell calculations of metalloporphyrins with different central metals indicate that the energy differences between these peaks reflect the electronic configurations and spin multiplicities of metalloporphyrins. We also investigated the hydration structure of CoPPIX in aqueous solution by analyzing the electronic structure of the ligand and revealed that CoPPIX maintains its five-coordination geometry in aqueous solution. The present study shows high performance of N K-edge XAS of ligands for studying the coordination structures of metalloporphyrins in solutions rather than the metal L2,3-edges of central metals.

МЕХАНІЗМИ МАСОПЕРЕНОСУ ІНДІЮ В Cd(Zn)Te ПРИ ДІЇ НАНОСЕКУНДНИХ ЛАЗЕРНИХ ІМПУЛЬСІВ

The processes of heating, melting and ablation during nanosecond laser irradiation of metal film (In) / CdTe structures and CdZnTe solid solutions are considered. Time and coordinate (in depth) temperature profiles during nanosecond laser irradiation of the system the film In/CdTe were calculated. Melting thresholds of indium and CdTe in the In/CdTe film system have been established. The profile of the distribution of indium atoms in cadmium telluride after a single laser irradiation of the In/CdTe structure, accompanied by the formation of an inversion layer (n-type), was obtained and theoretically described; a peak at a depth of 6 nm was detected. The mass transfer coefficients of indium in CdTe in different regions were determined during nanosecond laser irradiation of the In/CdTe structure with a thickness of the In film of 30 nm on the metal side at Epad = 100 mJ/cm2. It was established that the mass transfer coefficient of In atoms in CdTe during nanosecond laser irradiation of the In/CdTe film structure depends on the distance from the CdTe surface and increases, which is associated with a rapid change over time in the inhomogeneous deformation of the crystal lattice in the process of indium diffusion. The obtained value of the coefficient of laser-induced mass transfer of In in CdTe by an order of magnitude is much higher than the diffusion coefficients of impurities under normal annealing conditions with the diffusion method of impurity introduction and is commensurate with the self-diffusion coefficient in a number of liquid metals.

An inorganic-rich but LiF-free interphase for fast charging and long cycle life lithium metal batteries

Li metal batteries using Li metal as negative electrode and LiNi1-x-yMnxCoyO2 as positive electrode represent the next generation high-energy batteries. A major challenge facing these batteries is finding electrolytes capable of forming good interphases. Conventionally, electrolyte is fluorinated to generate anion-derived LiF-rich interphases. However, their low ionic conductivities forbid fast-charging. Here, we use CsNO3 as a dual-functional additive to form stable interphases on both electrodes. Such strategy allows the use of 1,2-dimethoxyethane as the single solvent, promising superior ion transport and fast charging. LiNi1-x-yMnxCoyO2 is protected by the nitrate-derived species. On the Li metal side, large Cs+ has weak interactions with the solvent, leading to presence of anions in the solvation sheath and an anion-derived interphase. The interphase is surprisingly dominated by cesium bis(fluorosulfonyl)imide, a component not reported before. Its presence suggests that Cs+ is doing more than just electrostatic shielding as commonly believed. The interphase is free of LiF but still promises high performance as cells with high LiNi0.8Mn0.1Co0.1O2 loading (21 mg/cm2) and low N/P ratio (~2) can be cycled at 2C (~8 mA/cm2) with above 80% capacity retention after 200 cycles. These results suggest the role of LiF and Cs-containing additives need to be revisited.

New understanding on the critical factors determining stability of passive film on Fe-Cr alloy based on aberration-corrected TEM study

Purpose In recent years, using aberration-corrected transmission electron microscopy, the authors have achieved precisely detecting the structural evolution of passive film as well as its interface zone at atomic scale. The purpose of this paper aims to make a brief review to show the authors’ new understanding and perspective on the issue of critical factors determining stability of passive film of Fe-Cr alloy. Design/methodology/approach The introduction of single crystal enabled the authors to obtain a distinct metal/passive film interface and better characterize the structure of the interface region. The authors use aberration-corrected TEM to conduct cross-sectional observation and directly capture the details across the entire film at a high spatial and energy resolution. Findings Apart from the passive film itself, the interface zone, including metal/film (Me/F) interface and the adjacent metal side, is also the site which is attacked. Accordingly, the nature of the interface zone, such as microstructure, composition and atomic configuration, is one of the critical factors determining the stability of passive film. Originality/value Deciphering the critical factors determining the stability of passive film is of great significance and has been a fundamental issue in corrosion science. Great attention has been paid to the nature of the passive film itself. In contrast, the possible role of the interface between the passive film and the metal is rarely taken into account. Based on the advanced analytical tool with high spatial resolution, the authors have specified the significant role of interface structures on the macro-scale stability of passive film.

Electro-chemo-mechanical properties of anodic oxide (passive) films formed on Cu, Ni and Fe

Abstract Electro-chemo-mechanical properties of anodic oxide (passive) films formed on metals have been reviewed focusing on the results of stress variations caused by anodic oxidation of Cu, Ni, and Fe thin film electrodes in deaerated pH 8.4 borate buffer solution at 25 °C. The surface stress varies toward compressive direction due to adsorption of OH on Cu from aqueous solution as well as adsorption of oxygen on metals from gas phase. The stresses are generated with the growth of three-dimensional anodic oxide films on metals. The magnitude and sign (tensile or compressive) of the intrinsic film stress were determined by taking the residual stress of the substrate and the dielectrostriction into consideration. The tensile or compressive intrinsic film stress depends on p-type or n-type semiconductive properties of the anodic oxide films, which is explained in terms of the void formation or oxide formation in the metal side at the metal/film interface. Furthermore, the stress variation toward compressive direction during cathodic reduction of the anodic oxide films is explained in terms of the volume expansion due to the formation of intermediate species.