Abstract: Mg$_3$Sb$_2$ is a promising thermoelectric material that consists of nontoxic and earth-abundant elements. We investigate metallic-atom diffusion in Mg$_3$Sb$_2$ by calculating the defect formation energy and the diffusion energy barrier for several kinds of metallic-atom impurities. We find that early transition metals, including $4d$ elements, with a large atomic radius have a high defect formation energy, whereas Mg and late transition metals such as Ni, Cu, and Zn have relatively low formation energies as interstitial impurities. Interstitial Ni, which is found to have a very low defect formation energy, might diffuse in the $ab$ plane at high temperatures with the energy barrier of 0.7 eV, while it seems difficult to diffuse in the $c$ direction. Interstitial Cu has a higher defect formation energy than Ni but has a low energy barrier of $\sim$0.4 eV for diffusion in the $ab$ plane. This study will offer important knowledge for developing a thermoelectric device of Mg$_3$Sb$_2$.

Abstract: Correction for ‘Accelerating the electrochemical performance of solid oxide fuel cells using a Ce(Gd, Bi, Yb)O 2− δ diffusion barrier layer acting as an oxygen reservoir at high-current loading conditions’ by Hye Young Kim et al. , J. Mater. Chem. A , 2025, https://doi.org/10.1039/d4ta06374k.

Abstract: <p><span>The performance of solid oxide cells (SOC) that employ mixed ionic-electronic conductors such as LSCF is typically limited by reaction with conventional stabilized-zirconia electrolytes. Ceria-based diffusion barrier layers prevent undesirable reactions and are thereby enhancing the electrochemical activity and durability of such electrodes. Recently, the implementation of physical thin-film methods to fabricate sub-micrometer barrier layers has led to strongly improved performance with respect to traditional fabrication methods. However, scalable and cost-effective manufacturing processes have not been proved to result in layers with sufficient quality, preventing the implementation of these improved barrier layers in commercially available cells. This study demonstrates the scalability of efficient barrier layers based on magnetron sputtering combined with rapid thermal processing (RTP). This approach reduces both the time and energy consumption compared to conventional processes. Electrochemical performance tests conducted on button cells recorded </span><span><span>1.26 W · cm⁻² </span></span><span><span>and </span></span><span><span>1.54 A · cm⁻² </span></span><span><span>at 0.7 and 1.3 V in fuel cell and electrolysis mode at 750 °C, respectively, which represents >30% increase compared to conventional reference cells. When scaled up to large-area cells (12x8 cm²), the RTP-treated cells measured as part of short stacks achieved up to approximately a 60% improvement in fuel cell conditions and 30% in electrolysis conditions compared with their reference counterparts at 650 ºC. The combination of magnetron sputtering and RTP offers a faster, scalable manufacturing process for high-performance SOCs, providing a viable route for large-scale production of high-performance barrier layers based on thin film technology. </span></span></p> <p><span> </span></p>

Abstract: In the past decade, significant efforts have been made to develop efficient half-Heusler (HH) based thermoelectric (TE) materials. However, their practical applications remain limited due to various challenges occurring during the fabrication of TE devices, particularly the development of stable contacts with low interfacial resistance. In this study, we have made an effort to explore a stable contact material with low interfacial resistance for an n-type TiCoSb-based TE material, specifically Ti_0.85Nb_0.15CoSb_0.96Bi_0.04 as a proof of concept, using a straightforward facile synthesis route of spark plasma sintering. We tested many metals with compatible coefficients of thermal expansion to TiCoSb, like Fe and Co. Still, we failed to form proper atomic bonds with the TE material. In contrast, Ti metal bonded correctly but showed very high electrical contact resistance (∼300 mΩ at one side), reducing performance due to Ti diffusion and a high potential barrier at the interface. This issue was addressed by highly doped semiconductor (HDS) contact Ti_0.7Nb_0.3CoSb, which matched the TE material in terms of atomic bonding, crystal structure, and stability. The leg with the HDS contact demonstrated superior electronic transport performance and low interface resistance (∼15 mΩ at one side), achieving a maximum output power of 30.7 mW at ΔT = 451 K due to the sharp interface with a low barrier height. These findings suggest that using HDS material as a contact with the same HH TE material would be an effective way to develop a TE device with low interface resistance and high thermal stability.

Abstract: Abstract To realize highly reliable ULSI-Cu interconnects, it is essential to employ liner and diffusion barrier materials that exhibit strong adhesion to Cu and excellent Cu diffusion barrier properties. We previously demonstrated that Co(W) alloy thin films fulfill these requirements; however, a quantitative evaluation of their barrier properties at ultrathin thicknesses (~1 nm), as used in actual ULSI devices, has not yet been conducted. In this study, we applied the time-lag method, which was originally developed to measure the diffusivity (D) of H₂ in porous rubber membranes, to quantitatively evaluate the barrier performance of a 1-nm-thick Co(W) film fabricated by magnetron sputtering (physical vapor deposition, PVD). The time-lag method enabled the measurement of Cu diffusion coefficients at various temperatures. The results revealed that the 1-nm-thick PVD-Co(W) films exhibited excellent barrier performance, characterized by a high diffusion activation energy of 2.1 eV, indicative of lattice diffusion. These results are comparable to those obtained for a 20-nm-thick PVD-Co(W) film, suggesting that reducing the film thickness does not compromise its barrier properties. This study demonstrates the applicability of the time-lag method for quantitatively assessing the barrier properties of ultrathin diffusion barrier layers.

Abstract: Despite the excellent thermoelectric properties of Te, the element diffusion and reaction at the interface with the metal electrodes introduce a large contact resistivity (ρ_c), significantly reducing the conversion efficiency (η) of the device. Therefore, suitable barrier layers are being sought to optimize the connection between Te and metal electrodes. In this study, a Sn-Te alloy barrier layer is reported based on interfacial reaction. The results show that there is no reaction layer and microscopic defects at the interface of SnTe/Te0.985Sb0.015 device, and the η of the single-leg device is approximately 4.7% at a temperature difference of 230 K. Meanwhile, the interface exhibits good thermal stability with no significant change in ρ_c, η and interface microstructure, after aging at 523 K for 18 days.

Abstract: In order to clarify the influence mechanism of Cr diffusion barrier layer on the oxidation performance of NiCrAlY coating under high temperature conditions， NiCrAlY coatings and NiCrAlY-Cr composite coatings with Cr barrier layers of different design thicknesses (50， 100，150 μm) were prepared using plasma spraying technology.The phase composition changes of the coatings were analyzed using X-ray diffraction(XRD)， while the microstructure of the coatings was examined using scanning electron microscopy (SEM).The element distribution in the coatings and oxidation layers was analyzed by energy dispersive spectrometer (EDS) attached to the SEM.The high-temperature oxidation behavior of NiCrAlY-Cr coatings with different thicknesses of Cr barrier layers was investigated.Results showed that both the deposited NiCrAlY and NiCrAlY-Cr coatings were mainly composed of Ni3Al.After oxidation at 850 °C for 30 h， both NiCrAlY and NiCrAlY-Cr coatings formed α-Al2O3 and Cr2O3 on their surfaces.When the oxidation temperature was increased to 950 °C， after 30 h of oxidation， all three NiCrAlY-Cr composite coatings with different Cr barrier layer thicknesses showed a dominant Ni3Al phase on their surfaces， along with the formation of α-Al2O3， Cr2O3， and characteristic diffraction peaks of NiCr2O4.After 65 h of oxidation at 850 °C， the main phases in NiCrAlY and NiCrAlYCr composite coatings with different thicknesses of Cr barrier layers were α-Al2O3， Cr2O3， NiCr2O4 and Ni3Al.With the extension of oxidation time to 100 h， the phases in the NiCrAlY coatings and NiCrAlY-Cr composite coatings with Cr barrier layers of different design thicknesses remained dominated by α-Al2O3， Cr2O3， NiCr2O4 and Ni3Al after oxidation at both 850 °C and 950 °C.The dense protective layer formed by α-Al2O3， Cr2O3 and NiCr2O4 on the surface of NiCrAlY-Cr coatings in high-temperature environments provided significantly better high-temperature oxidation resistance compared to NiCrAlY coatings.

Abstract: ABSTRACT In this study, we investigate the potential of bimetallic MXenes as advanced anode materials for lithium‐ion batteries (LIBs) and sodium‐ion batteries (NIBs). Using first‐principles density functional theory (DFT), we systematically examined the electrochemical performance of Zr‐based bimetallic MXenes, Zr 2 MC 2 O 2 , and M 2 ZrC 2 O 2 ( M = Sc, Ti, V), including their structural stability, electronic properties, adsorption characteristics, and ion diffusion behavior. The strategic incorporation of 3d transition metals induces pronounced synergistic effects, significantly enhancing electronic conductivity, with Sc 2 ZrC 2 O 2 exhibiting the highest density of states at the Fermi level (9.375 states/eV). The computed adsorption energies confirm strong Li/Na interactions, particularly in Sc 2 ZrC 2 O 2 , which displays exceptional adsorption affinities of −2.754 and −2.241 eV for Li and Na, respectively. Additionally, Sc 2 ZrC 2 O 2 achieves a remarkable theoretical specific capacity of 429 mA h g −1 for NIBs and 213 mA h g −1 for LIBs. Furthermore, Zr 2 TiC 2 O 2 exhibits the lowest average open‐circuit voltage (OCV), measured at 0.33 V for NIBs and 1.23 V for LIBs. Notably, the introduction of 3d transition metals enhances Na‐ion diffusion while selectively optimizing Li‐ion mobility, with Sc 2 ZrC 2 O 2 exhibiting the lowest Li‐ion diffusion barrier (0.273 eV) and Zr 2 TiC 2 O 2 facilitating Na‐ion transport with the lowest diffusion barrier (0.309 eV). Furthermore, structural stability analysis confirms that these MXenes exhibit minimal lattice distortion and robust mechanical integrity during lithiation and sodiation. Our results highlight the synergistic effects of transition metal combinations in tailoring the electrochemical properties of MXenes, positioning them as promising candidates for high‐performance anode materials in energy storage applications.