The Korean Society of Surface Science and Engineering

Aqueous zinc-ion batteries (AZIBs) are gaining attention as safe, low-cost, and environmentally friendly energy storage systems. Despite progress in Zn metal anode stabilization, cathode optimization remains the primary challenge limiting practical performance. This review categorizes the major degradation mechanisms of AZIB cathodes into four pathways: dissolution of active materials, formation of by-products, structural distortion caused by repeated Zn²⁺/H⁺ insertion, and intrinsic limits in theoretical capacity. Based on this framework, we examine key cathode families-Mn-based oxides, V-based oxides, Prussian blue analogues (PBAs), and metal–organic frameworks (MOFs) and their derivatives, highlighting structural features, charge-storage mechanisms, failure modes, and recent engineering strategies. Approaches such as pre-intercalation, defect/interface engineering, electrolyte optimization, conductive composites, and MOF-derived architectures are emphasized as effective routes to enhance stability and Zn²⁺ transport. Finally, design principles and future research directions for high-performance AZIB cathodes are proposed.

Aqueous Zinc-ion Batteries; Cathode Degradation; Mn- and V-based oxides; Prussian blue analogues; Metal–organic frameworks.

Owing to its distinctive and valuable physical properties, lead scandium niobate (Pb(Sc_1/2Nb_1/2)O₃) has continued to attract significant research interest across various scientific disciplines, despite its limited environmental compatibility. In the present study, the structural characteristics and physical properties—including ferroelectric behavior—of disordered Pb(Sc_1/2Nb_1/2)O₃ ceramics synthesized at temperatures ranging from 1320℃ to 1380℃ were systematically examined. Among the synthesized samples, the specimen sintered at 1350℃ for 2 hours exhibited the most complete perovskite singlephase structure. Under these optimized conditions, a broad relaxation phenomenon associated with space-charge and dipolar interactions was observed across a wide temperature range. The corresponding dielectric constant and dielectric loss were approximately 36,720 and 0.039, respectively. The complex admittance of Pb(Sc_1/2Nb_1/2)O₃ was measured as the temperature was increased in 30℃ increments from room temperature, enabling detailed analysis of its frequency-dependent electrical response. The results indicate that the frequency response is strongly correlated with the polarization mechanism and energy dissipation processes intrinsic to ferroelectric materials. Furthermore, Pb(Sc_1/2Nb_1/2)O₃ exhibited a pronounced frequency dependence within the phase transition region and evident thermal hysteresis between heating and cooling cycles. The critical exponents derived from the heating and cooling experiments were 1.15 and 1.58, respectively, confirming the material’s diffuse phase transition behavior.

Pb(Sc_1/2Nb_1/2)O₃; Frequency dependence; Complex admittance; Dielectric relaxation.

Gadolinium oxide (Gd₂O₃) and boron carbide (B₄C) composites layers on 304-stainless steels were plasma thermal spray coated to make a high thermal neutron absorption and shielding layers for a nuclear spent fuel transportation and storage container and a high-level nuclear wastes canisters. The coating layers contained Gd₂O₃, B₄C and binder Ni alloy. More than 100㎛ thick coating layers with a 1:1 ratio of the neutron absorber material and the binder nickel alloy were able to shield 100% neutron against the neutron beam with the 48.4 meV energy and 0.13 nm wavelength that was higher the neutron energy of domestic spent nuclear fuels undergone 30 years of cooling in a spent fuel pool. The corrosion current density and potential of the coating layers in an artificial sea water were less than 10^-6 A/cm² and lower than -835 mV_SHE, respectively. These results support that the plasma coating layers can be well applicable as the thermal neutron shielding materials for a domestic spent nuclear fuel transportation and storage containers.

thermal plasma spray coating; gadolinium oxide; boron carbide; spent nuclear fuel; corrosion; neutron shielding efficiency.

Palladium (Pd) coatings were electrodeposited on copper (Cu) substrates using an ammonium-free electrolyte to investigate the effect of coating thickness on the microstructure and electrochemical properties. SEM analysis revealed that the Pd coating exhibited a porous and discontinuous surface at 0.25 μm, whereas a dense and smooth morphology was obtained at 1.0 μm. At 1.5 μm, localized overgrowth and surface roughening were observed due to stress accumulation during prolonged electrodeposition. TEM analysis of the Pd/Cu interface confirmed a coherent lattice structure without amorphous transition, indicating strong interfacial adhesion. XRD results showed typical face-centered cubic (fcc) Pd peaks corresponding to the (111), (200), and (220) planes, with the (111) reflection becoming dominant as the coating thickness increased. A weak PdO peak was detected near 34° for the 1.5 μm coating, implying partial surface oxidation. Electrochemical measurements in 3.5 wt% NaCl solution demonstrated that the corrosion potential Ecorr shifted positively from −0.30 V to −0.15 V, and the charge transfer resistance Rct increased from 1.2 × 10³ to 4.1 × 10³ Ω·cm² as the thickness increased from 0.25 to 1.0 μm. The coatings with thicknesses of 0.5–1.0 μm exhibited the highest corrosion resistance and electrochemical stability, attributed to their compact microstructure and strong (111) orientation. These findings confirm that optimizing the Pd coating thickness significantly enhances corrosion resistance and interfacial stability, establishing Pd electrodeposition as a promising and environmentally sustainable alternative to Au plating for electronic and semiconductor applications. This study aims not only to elucidate the relationship between Pd coating thickness, microstructural evolution, and electrochemical stability, but also to provide design criteria for the development of eco-friendly plating processes applicable to high-reliability electronic components.

Palladium (Pd) coating; Copper substrate; Ammonium-free electrolyte; Microstructure; Corrosion resistance; Electrochemical impedance spectroscopy (EIS).

The molybdenum(Mo) doped indium oxide (IMO) films were deposited on glass substrates by RF magnetron sputtering and the films were vacuum annealed at 150, 300, and 450℃, respectively to investigate the influence of the annealing temperature on the electrical and optical properties of the films. The grain size of In₂O₃(222) plane increased up to 32.93 nm with annealing temperatures and their electrical resistivity decreased from 2.0×10^-3 Ωcm to 9.7×10^-4 Ωcm at the 450℃ annealing. The visible transmittance also improved from 77.62 to 80.82% when the annealing temperature increased. The optical band gap of the post-deposition annealed films increased from 3.702 to 3.751 eV proportionally with annealing temperature. The figure of merit shows that the IMO films annealed at 450℃ had better optical and electrical performance than the other films prepared using lowertemperature conditions. The observed results suggested that the post-deposition vacuum annealing is the one of effective process for the increasement of electrical and optical property of IMO thin films.

Magnetron sputter; IMO; Thin fim; Vauum anneaning; Figure of merit.

The availability of highly reliable p-type two-dimensional (2D) semiconductors is essential for implementing complementary logic circuits, low-power electronics, and multi-functional devices. Despite significant progress in 2D field-effect transistor (FET) research, studies on p-type materials and their device applications remain insufficient. In this study, we report on the fabrication and electrical characterization of p-type FET based on 2D tungsten diselenide (2D-WSe₂) synthesized via a two-step synthetic method. The optimized process involving sequential tungsten trioxide (WO₃) precursor deposition and selenization, yielded few-layer 2D-WSe₂ films with controlled thickness. The fabricated back-gate transistors exhibited a clear p-type conduction behavior, with an on/off current ratio exceeding 10³, a hole mobility of 0.03 cm²/V·s, and a low gate leakage current of < 0.2 nA. Also, the synaptic characteristics were evaluated under successive pulse measurements, and stable operation was confirmed up to 400 cycles.

2D-WSe₂; Two-step CVD selenization; Back-gate transistor; Synatpic properties; Field-effect mobility.

This study employed a sealed immersion test cell to conduct long-term monitoring of the corrosion resistance of metallic specimens (POSSEN, STS304, and Steel) in NaCl solution. While conventional electrochemical evaluation methods provide high precision, their application is limited in inaccessible environments. To address this, a non-contact, non-destructive image-based analysis technique was utilized to quantitatively assess corrosion progression. Leveraging the zero-shot transferability and prompt-based segmentation capability of the Segment Anything Model (SAM), specimen regions were effectively separated from the container and background, ensuring stable image acquisition even under variations in lighting and solution transparency. The segmented specimen regions were converted into CIELab and HSV color spaces, and temporal changes in color values were analyzed to quantitatively characterize the initiation and progression of corrosion. The proposed method improves the accuracy and reliability of corrosion resistance evaluation under conditions with environmental variability, and holds potential for long-term corrosion monitoring and material performance assessment in various industrial settings.

POSSEN; Immersion test; Segment Anything Model; Image-based analysis.

To ensure the reliability of the atomic layer etching (ALE) process, it is essential to employ real-time monitoring of the adsorption (deposition) step. In this study, a quartz crystal–based polymer sensor was developed to enable real-time detection of radical adsorption. The operational characteristics of the sensor were evaluated using an ALE system equipped with a radical generation module designed to allow energetic radicals and neutral species to reach the substrate. The sensor frequency changed linearly in response to variations in the amount of radicals adsorbed and deposited on the sensor surface, confirming its ability to monitor process conditions. The frequency shift exhibited a linear proportional relationship with adsorption (deposition) time, and XPS analysis revealed that the amount of radicals generated from the decomposition of the etching gas C₄H₂F₆ increased with longer adsorption time. Furthermore, this increase in radical adsorption was found to proportionally enhance the etch per cycle (EPC).

Diagnostics; Plasma; ALE (Atomic Layer Etching); Radical.

This study focuses on the evaluation of ultra-thin copper foil properties used in the bottom-up copper electroplating process for filling Through Glass Via(TGV) holes. The foils are also applicable for forming high-density Redistribution Layers (RDL) on glass substrates with pre-formed TGVs. To ensure analytical accuracy, multiple complementary characterization methods were employed for surface and interface analysis and for assessing the release layer properties. The investigation covered various physical properties, including surface and cross-sectional morphology, layer structure, thickness, and crystallite size. In particular, detailed analyses were conducted on key layers affecting adhesion strength such as the Cu nodule layer, interfacial layer, adhesion layer, and release layer. Four types of copper foils were characterized using similar procedures. Based on thorough analyses, foil #1 was identified as having a Carrier Cu/Ni/Organic layer/Thin Cu structure; foil #2 exhibited a multilayer structure comprising Carrier Cu/Ni-P/Mo-Fe-Ni/Ni/Thin Cu. foil #3 showed a Carrier Cu/Ni-P (diffusion barrier)/Mo-Fe-Ni (release layer)/Thin Cu/Nodulous Cu structure; and foil #4 was confirmed to have a Carrier Cu/Ni-Mo/Thin Cu/nodule Cu structure. This study is expected to provide fundamental insights into release characteristics through detailed analyses of the carrier copper foil structure, establish cross-analytical methodologies, and suggest design strategies for optimal release performance, thereby supporting the application of ultra-thin foils in TGV technology.

TGV(Through Glass Via); Buttom-up copper electroplating; Release copper foil; Surface analysis; interface characteristic.

This study investigates the effect of PF₅–C₄F₈ mixed-gas composition on the SiO₂ etching characteristics in an inductively coupled plasma (ICP) etching system operated at a low temperature of –30 ℃. The behavior of reactive species in the plasma was analyzed using optical emission spectroscopy (OES), while neutral and ionic species that are difficult to detect with OES were identified using quadrupole mass spectrometry (QMS). The analysis revealed that PF₅ generated high-mass PF_x ions together with fluorine radicals, inducing physical bombardment on the substrate surface. Meanwhile, C₄F₈ exhibited a high dissociation rate, producing F and CF_x radicals that enhanced chemical etching reactions. In addition, increasing the bias power elevated the physical contribution of PFx ions, resulting in a higher overall etch rate. These observations quantitatively demonstrate the etching behavior and plasma chemistry occurring under PF₅–C₄F₈-based low-temperature plasma conditions.

Reactive Ion Etching, Plasma, Low-Temperature

This study explores the microstructural evolution, crystallographic development, electrochemical stability, discoloration resistance, and electrical performance of non-cyanide silver (Ag) coatings engineered for high-reliability electric vehicle (EV) relay contacts. Ag coatings with thicknesses ranging from 0.25 to 1.50 μm were deposited using a thiosulfate-based electrolyte containing thiourea, polyoxyethylene, and amine-type additives. Surface characterization revealed progressive grain refinement—from 125 to 75 nm—and a reduction in surface roughness from 43 to 28 nm, resulting in a highly compact and uniform microstructure at a thickness of 1.00 μm. X-ray diffraction analysis further confirmed enhanced crystallinity and a strengthened Ag(111) preferred orientation at this optimum thickness, accompanied by reduced peak broadening. Electrochemical measurements demonstrated improved corrosion resistance with increasing thickness, as evidenced by a positive shift in corrosion potential and a significant decrease in corrosion current density. Impedance analysis showed the highest charge-transfer resistance (4.1 kΩ·cm²) at 1.00 μm, indicating the most stable electrochemical interface. Accelerated aging tests (85 ℃, 85% RH) revealed excellent discoloration resistance, with ΔE values below 1.5 for 1.00 μm and thicker coatings. Electrical assessments confirmed low surface resistivity (~0.43 mΩ/sq) and superior thickness uniformity (±4–7%), both critical for maintaining stable contact resistance under repeated relay switching. These findings demonstrate that the optimized 1.00 μm Ag coating achieves a balanced enhancement in microstructural compactness, crystallographic stability, corrosion resistance, and environmental durability. The results provide a practical design guideline for eco-friendly, non-cyanide Ag plating processes for EV relay contacts and other high-reliability electronic components.

Silver plating; Discoloration suppression; EV relay; Electrochemical analysis; Process optimizatio.

Polyetheretherketone (PEEK) has been widely utilized in spinal implants owing to its favorable mechanical properties and radiolucency. Nevertheless, its intrinsically bio-inert surface limits direct bone attachment, often resulting in delayed osseointegration. Titanium coating has been proposed as an effective strategy to improve the interfacial bioactivity of PEEK, and among the available coating methods, physical vapor deposition (PVD) offers distinct advantages such as low processing temperature and the ability to produce uniform thin films without thermal degradation of the polymer substrate. This study aimed to evaluate the mechanical adhesion behavior of PVD titanium coatings applied to PEEK surfaces prepared under two different pre-processing conditions: machining (smooth surface) and zirconia bead blasting (rough surface). Adhesion performance was quantitatively assessed through tensile adhesion strength (ASTM F1147-05), shear adhesion strength (ASTM F1044-05), and fatigue shear testing (ASTM F1160-14). The tensile adhesion strength of the machining group was approximately 25% higher than that of the sanding group, whereas shear adhesion strength showed no significant difference between groups. Both surface conditions demonstrated stable performance under 10 million cycles of repeated shear loading without evidence of delamination or particle generation. The results indicate that PVD titanium thin films can establish mechanically stable interfaces on PEEK substrates. The reduced tensile adhesion in the roughened group may be attributed to discontinuities in the deposited thin film and limitations of adhesive layer uniformity required in ASTM-based testing. Considering the inherent characteristics of thin-film deposition under vacuum, clinically optimal roughness levels for osseointegration (Ra 2–3 μm) may still be advantageous when combined with uniform PVD coating. Further studies incorporating additional surface roughness levels, coating parameters, and biological evaluations are warranted to optimize coating strategies for clinical applications.

PEEK; titanium coating; PVD; adhesion strength; shear strength; fatigue durability; surface roughness; spinal implants.

Cast aluminum alloy A356 exhibits microstructural heterogeneity associated with Si particles, which undermines the uniform growth of anodic oxide and limits long-term corrosion resistance. Generally, corrosion resistance of aluminum alloys can be significantly enhanced by an anodizing, which creates nanoporous oxide layer on surface. However, the anodizing of casting aluminum alloys is not widely explored compared to wrought aluminum alloys. This study evaluated the anodization behavior and performance of A356 alloy under constant current conditions, with or without ethylene glycol (EG), and in low and sub-zero temperature environments. With a mixing the sulfuric acid with EG, the temperature of electrolyte can be decreased to –15 ℃. The required electric field during the anodizing increased with a decrease of electrolyte temperature. Some voids in anodic oxide were observed around the Si particles. Anodic oxide created at sub-zero temperatures (-15 ℃) shows a lower content of sulfuric acid, and higher hardness compared to the anodic oxides formed at 0 ℃ and 15 ℃. Moreover, anodized A356 alloy at –15 ℃ had a better corrosion resistance than other samples. Therefore, the anodizing process combining EG mixing and sub-zero temperature reducing the sulfate ions in the anodic oxide can provide a new solution for surface treatment of casting aluminum alloys to enhance the surface hardness and corrosion resistance.

A356 cast aluminum alloy; Anodization; Sulfuric acid; Corrosion resistance.

Electrophoretic deposition (EPD) has emerged as a promising electrode fabrication technique owing to its ability to form uniform coatings and its high flexibility in solvent and component selection. In this study, an N-methyl-2-pyrrolidone (NMP)-free and binder-free EPD process was developed to fabricate LiFePO₄ (LFP) cathodes, addressing both the environmental concerns and the electrochemical limitations associated with conventional slurry-based electrode manufacturing. Surface-engineered aluminum current collectors with hierarchical tunnel structures were combined with acidfunctionalized carbon nanotubes to simultaneously enhance particle dispersion, electrode cohesion, and interfacial adhesion without the use of polymeric binders. As a result, binder-free LFP cathodes with mechanically robust architectures were successfully obtained via EPD. Electrochemical evaluation revealed that the EPD-fabricated cathodes exhibited superior capacity and cycling stability compared to conventional slurry-cast electrodes. These results demonstrate that EPD, when coupled with appropriate interface and microstructure engineering, represents a viable and sustainable electrode fabrication strategy for high-performance lithium-ion batteries.

LFP electrode; Electrophoretic deposition; Binder-free electrode.

The thermal stability of Cu surface anti-oxidation film is crucial for high-temperature electronic packaging, particularly in next-generation SiC and GaN power semiconductor devices operating at ≥ 200 ℃. This study examines two improved BTA-based inhibitors(AT-1, AT-5) under three industrial reflow environments-N₂ convection, formic acid conduction, and PFPE condensation-to evaluate their chemical, electrical, and mechanical stability. XPS and surface-resistance analyses confirmed that both inhibitors effectively suppressed Cu oxidation during reflow, though with a slight increase in resistance compared with bare Cu. AT-1 demonstrated superior oxidation inhibition in the formic-acid atmosphere, whereas AT-5 under N₂ conditions delivered the best overall performance, producing the thinnest oxide layer (similar to bare Cu), the lowest surface resistance, excellent solder wettability, and the highest bonding strength. In contrast, PFPE conditions resulted in significantly thicker oxide layers and the lowest bonding strengths for all samples. These findings highlight the strong dependence of BTA-based inhibitor stability on the reflow environment and provide practical guidance for selecting optimal anti-oxidation coatings in high-reliability power semiconductor packaging.

Corrosion inhibitor; Copper&Copper alloy; Power semiconductor; Benzotriazole.