Journal of Materials Science最新文献

In this study, the effects of Al₂O₃ and Y₂O₃ passivation layers on Ge substrates are investigated to enhance the thermal stability of Ge-based devices. Using X-ray photoelectron spectroscopy, we analyze the growth characteristics and chemical composition of Al₂O₃, Y₂O₃, and ZrO₂ on Ge. The changes in the crystallinity of ZrO₂ on different substrates of Ge, Al₂O₃/Ge, and Y₂O₃/Ge configurations are observed via X-ray diffraction. Material properties, including capacitance, flat band voltage shift (ΔV_FB), oxide charge trap (N_ot), interface defect density (D_it), and leakage current, are analyzed using the metal–oxide–semiconductor capacitor, with a particular focus on their electrical characteristics. Additionally, we investigate whether the passivation mechanisms of each material are more suitable for enhancing thermal stability. Overall, this study provides insight into the role of passivation layers in improving the interface and thermal stability of Ge-based devices, offering valuable contributions to the advancement of semiconductor technology.

Graphical abstract

In this work, the effects of Nb micro-alloying on the stress corrosion cracking (SCC) behaviors of the heat-affected zone (HAZ) of high-strength low-alloy (HSLA) steel exposed to SO₂-polluted seawater were investigated using electrochemical measurements, static load U-bend immersion tests and slow strain rate tensile experiments combined with fractographic observations. Results indicated that Nb existed in solute status in the coarse-grained HAZ (CGHAZ) while simultaneously in the form of solute status and NbC precipitate in the fine-grained HAZ (FGHAZ) and inter-critical HAZ (ICHAZ). With reduced prior austenite grain sizes, Nb micro-alloying refined the lath bainite in the CGHAZ as well as induced the formation of acicular ferrite in the FGHAZ and granular bainite in the ICHAZ. Moreover, the three types of HAZ microstructures had a high SCC susceptibility in SO₂-polluted seawater in the increasing order of ICHAZ < FGHAZ < CGHAZ under the combined mechanism of anodic dissolution and hydrogen embrittlement. Nevertheless, attributing to the variations of microstructural constituents and the presence of NbC precipitates, Nb micro-alloying was capable to enhance the SCC resistance of HAZ microstructures by inhibiting the initiation and propagation of SCC cracks, with the SCC susceptibility decreased by ~ 5%, ~ 28% and 24% for CGHAZ, FGHAZ and ICHAZ, respectively.

The impacts of La additions on the microstructures, corrosion resistance and discharge performance of the as-cast Mg–6Al–3Pb (wt. %) anodes for Mg–air batteries were systematically investigated. The Mg–6Al–3Pb–xLa (x = 0, 0.5, 1 and 2 wt. %) alloys primarily consisted of α-Mg, β-Mg₁₇Al₁₂, Al₁₁La₃ and LaAl₃ phases. The results indicated that the addition of La could not only increase the volume fraction of the second phase, leading to the formation of Al₁₁La₃ and LaAl₃ phases, but also effectively promote grain refinement. In terms of discharge performance, the AP63–1La alloy exhibited a high steady discharge voltage of −1.71 V (vs. SCE) at 10 mA·cm⁻². Regarding corrosion behaviors, the corrosion resistance of the alloys initially decreased and then increased with increasing La content. Notably, the AP63–2La alloy demonstrated the best corrosion resistance, due to the high proportion of acicular second phase inhibiting the corrosion process.

Synthesized DE@HTDMS-SiO₂ particles loaded with TiO₂ nanoparticles, linked to adhesive epoxy resin and the green hydrophobic agent cetyltrimethoxysilane, were utilized to fabricate superhydrophobic composite coatings on various substrates using a simple spraying technique. The resulting composite coating exhibited a contact angle of 156.6° and a rolling angle of 7.6°, demonstrating excellent self-cleaning properties, antifouling capabilities, and durability. The photocatalytic performance was evaluated by using visible light from a 220 W incandescent lamp as a light source. The results indicated that the composite coating could degrade both RhB and MB solutions by over 90%. In a custom-made oil–water separation device, the composite-coated cotton fabric achieved a separation efficiency exceeding 96% for mixtures of n-hexane and diesel. Even after 10 cycles of repeated separation, the efficiency remained above 89%. This underscores the composite coating’s remarkable photocatalytic performance and its capacity for efficient, recyclable oil–water separation. Furthermore, the hydrophobic angle of the composite superhydrophobic glass sheet decreased by only 2.3° after undergoing a three-month outdoor aging experiment. Additionally, the composite-coated cotton fabric maintained a certain level of hydrophobicity even after being submerged in a strong alkali solution for 24 h.

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The hydrolysis of silicon and its compounds to produce hydrogen for fuel cell remains a major problem. The main obstacle is the weak hydrolytic activity and slow kinetics of silicon. In this work, the alloying properties of Si and Ca to improve its hydrolytic activity, and studied the film breaking effect of different metals and halogen ions on its passivation layer. The results show that the hydrogen production of the alloy is still determined by its phase composition. Among the common metal (Ni, Bi, Sn) and halogen ions (F^–, Cl^–) catalyzed by hydrolysis, Ni and F^– showed a good synergistic effect, resulting in a hydrogen yield of 269 mL/g at room temperature without alkali.

Graphical Abstract

The effects of metal ions and halogens on the hydrolytic properties of Ca–Si alloy were investigated, and Ni²⁺ and F^— showed good synergistic effect.

The corrosion resistance of Zr₅₅Cu₃₀Al₁₀Ni₅ amorphous alloys fabricated by twin-roll strip casting using various process parameters was systematically investigated compared with 316 stainless steel. Potentiodynamic polarization tests indicated that pure amorphous alloy sheets possessed the best passivation in NaOH and H₂SO₄ solutions, but pitting corrosion was observed in NaCl solution. In NaOH and H₂SO₄ solution, the corrosion current density of amorphous matrix is increased by nearly two times, and the corrosion rate increases accordingly. The presence of Al-rich microcrystallites retained from the melt in the amorphous matrix reduces the corrosion resistance of the sheets. The preferential attack occurs on the microcrystallites due to the formation of a passivation film of composition and structure different from that of the substrate. The study on the corrosion properties of twin-roll cast-rolling amorphous provides theoretical guidance for expanding its practical application. It provides new ideas to extend the application of amorphous alloys in practical environments.

Bi₂O₃ is an excellent visible light photocatalyst. However, the structural instability limits its activity and engineering application. To enhance the activity and stability, the composite of CQDs and Bi₂O₃ was constructed by solvothermal method, and the physical–chemical properties of prepared composite were characterized using XRD, TEM, XPS, FTIR and TPC. As the target pollutant, bisphenol A (BPA) was used to investigate the photocatalytic activity and the stability of CQDs@Bi₂O₃ by photodegradation experiment under the irradiation of simulated visible light, and butyl xanthate was used to prove the applicability by mung bean sprouts. As the results, the existence of CODs obviously promoted the photocatalytic activity of Bi₂O₃:10% CQDs@Bi₂O₃ could remove 93.7% of BPA in 120 min, and the reaction constant rate was almost 1.5 time of pure Bi₂O_3. Moreover, 10%CQDs@Bi₂O₃ could effectively remove butyl xanthate and greatly reduce the growth toxicity on mung bean sprouts. After doping with CQDs, the electron transfer path on the surface of the catalyst could effectively inhibit the electron–hole composite and improve the stability of the composite to a certain extent.

This study investigates the structural, optoelectronic, magnetic and thermophysical properties of three newly designed semiconductor pyrochlore oxides, namely RE₂Ti₂O₇ (RE = Er, Eu, Tb), using ab-initio calculations within the density functional theory framework. The values of indirect bandgaps are 3.8, 2.2 and 3.77 eV for the spin up channel of Er₂Ti₂O₇, Eu₂Ti₂O₇, and Tb₂Ti₂O₇, respectively. While the values of indirect bandgaps for the spin down channel of Er₂Ti₂O₇, Eu₂Ti₂O₇, and Tb₂Ti₂O₇ are 3.56, 3.65 and 2.1 eV, respectively. The paramagnetic magnetic moments can be inferred by analyzing the distinct band shapes observed in the energy band structures of the studied compounds corresponding to the spin up and spin down states. The magnetic moments of Er₂Ti₂O₇, Eu₂Ti₂O₇, and Tb₂Ti₂O₇ have significant magnitudes, specifically measuring 12.00, 24.51, and 24.00 ({mu }_{B}), respectively. Significant absorption of incident photons by the studied compounds can be noted in near UV region in both spin channels. Low reflectivity (~ 30%) by RE₂Ti₂O₇ (RE = Er, Eu, Tb) is evident from the (R(omega )) spectra in an energy range of 1.0–10.0 eV. However, these compounds exhibit ~ 50% reflectance of the incident photons in upper UV region (above 10.0 eV). The analysis of the Seebeck coefficient spectra reveals that RE₂Ti₂O₇ (RE = Er, Eu, Tb) exhibits p-type semiconductor behavior, however, Eu₂Ti₂O₇ also shows n-type behavior from 200 to 450 K. The presented thermodynamic characteristics reveal that the pyrochlore oxides RE₂Ti₂O₇ (RE = Er, Eu, Tb) exhibit thermal stability.

In order to obtain a building thermal storage material with excellent thermal performance, sufficient strength and low leakage, the advantages of ternary PCMs (Lauric acid—Palmitic acid—Tetradecyl alcohol, LA-PA-TA) and vitrified beads (VB) as a adsorbent carrier were integrated to prepare a novel LA-PA-TA/VB composite PCM which exhibited favorable phase change temperature (i.e. 20.1–20.5°C) and low sub-cooling (0.4°C). Then, the novel LA-PA-TA/VB was, respectively, encapsulated with five different materials (a true stone paint emulsion, styrene-acrylic emulsion, EVA emulsion, epoxy resin and cement powder) to form a shape-stabilized LA-PA-TA/VB (SS-LA-PA-TA/VB) in order to reduce the leakage. The mass loss and mechanical properties experiments showed that SS-LA-PA-TA/VB encapsulated with the real stone paint emulsion-cement powder presented the optimal stability and reliability with low mass loss ratio of only 2.67% after 50 phase change cycles. The SS-LA-PA-TA/VB with the optimal package was further prepared into a thermal energy storage mortar (TESM) with different SS-LA-PA-TA/VB contents. The results show that the thermal properties of the TESM increased and the mechanical properties decreased with SS-LA-PA-TA/VB contents. However, even with the TESM with 30 wt% SS-LA-PA-TA/VB (30TESM), the compressive strength, flexural strength etc. still satisfy the requirement of the Chinese National Standard. The analysis shows that the hydrophobic functional groups are attached to the surface of the emulsion of the real stone paint, whereby a stable hydrophobic film was formed. In addition, the temperature regular ability and heat insulation performance of 30TESM and the referenced mortar were compared by temperature probe embedded inside the mortar blocks and installed in a small experimental room. The results indicated that the internal temperature of the mortar blocks, backside and central temperature in the small room was 5.4°C,5.6°C and 2.1°C lower than those of the referenced group, respectively. It is thus clear that the novel low cost TESM exhibits a good temperature damping effect and temperature control performance and may have a widespread application in the areas of building energy conservation.