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The discoloration switching appearing in the initial and final growth stages of 4H-silicon carbide (4H-SiC) single crystals grown using the physical vapor transport (PVT) technique was investigated. This phenomenon was studied, investigating the correlation with linear-type micro-pipe defects on the surface of 4H-SiC single crystals. Based on the experimental results obtained using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and micro-Raman analysis, it was deduced that the orientation of the 4H-SiC c-axis causes an axial change that correlates with low levels of carbon. In addition, it was confirmed that the incorporation of additional elements and the concentrations of these doped impurity elements were the main causes of discoloration and changes in growth orientation. Overall, this work provides guidelines for evaluating the discoloration switching in 4H-SiC single crystals and contributes to a greater understanding of this phenomenon. [ABSTRACT FROM AUTHOR]

In this study, Al2O3–siloxane composite thermal pads were fabricated using a tape–casting technique, and the thermal conductivity effect of the Al2O3 nanoparticle powder synthesized using a flame fusion process on siloxane composite thermal pads was investigated. Furthermore, various case studies were implemented, wherein the synthesized Al2O3 nanoparticle powder was subjected to different surface treatments, including dehydration, decarbonization, and silylation, to obtain Al2O3–siloxane composite thermal pads with high thermal conductivity. The experimental results confirmed that the thermal conductivity of the Al2O3–siloxane composite pads improved when fabricated using surface–treated Al2O3 nanoparticle powder synthesized with an optimally spheroidized crystal structure compared to that produced using non–treated Al2O3 nanoparticle powder. Therefore, this study provides guidelines for fabricating Al2O3–siloxane composite thermal pads with high thermal conductivity in the field of thermal interface materials. [ABSTRACT FROM AUTHOR]

Since the emergence of layered two-dimensional materials, the development of methods for their large-scale synthesis has become crucial for integrating these materials into existing fabrication processes. In this study, we report the synthesis of a NiTe2 single crystal on the near-centimeter scale using the molten salt flux method (MSFM). The single-crystal nature of the synthesized NiTe2 sample was confirmed using X-ray diffraction analysis, while its chemical characteristics were analyzed using X-ray photoelectron spectroscopy, which confirmed Ni–Te chemical binding. The layered structure of the ingot was confirmed using Raman spectroscopy; two prominent signals were observed, at 84 and 138 cm−1, which were consistent with the in-plane vibrational mode, Eg, and out-of-plane vibrational mode, A1g. In addition, analyses performed on different flakes confirmed the structural uniformity of the single crystal, as only a small variation in the peak-to-peak position of the full width at half maximum was observed. Using Kelvin probe force microscopy, the electronic structure of the NiTe2 multilayered surface was investigated to determine its surface work function, which was found to be 4.4–4.8 eV. A back-gate field-effect transistor was fabricated using the single-crystal NiTe2 to evaluate its semimetallic characteristics; the transfer characteristic of the NiTe2 FET, determined by applying a back-gate bias, showed weak gate voltage dependence and linear I–V characteristics, in keeping with the linear ID-VD output characteristics. Therefore, the synthesis of NiTe2 via the MSFM should facilitate the integration of layered materials with existing fabrication processes for the mass production of electronic devices. [ABSTRACT FROM AUTHOR]

Superhydrophobic coatings are widely studied for fluid regulation due to their water-repellent surface characteristics. However, there are not many reports on fluid behavior when it flows from a region of higher wettability to that of lower wettability. A fundamental understanding of such behavior would be very useful for regulating the fluid flow through a superhydrophobic channel. Therefore, this work focused on the fabrication of superhydrophobic nanostructured coatings inside fine cylindrical channels and the investigation of the fluid flow behavior through them. The superhydrophobic SiO2 coatings were obtained through an ultrasound-assisted one-step immersion technique. A self-stratified mechanically durable conformal superhydrophobic coating was obtained inside millimeter-sized fine 3D structures. A binder-free precursor solution has low viscosity and thereby enhances the penetration of the solvent into the polymer surface through ultrasonication. The self-stratification-based surface formation mechanism was explained using scanning electron microscopy images. The fluid behavior inside the superhydrophobic channels was experimentally investigated by analyzing the flow through the hollow cylindrical superhydrophobic channels. Experiments were conducted for different channel lengths (l) and radii (r), and mathematical formulations were developed to determine the maximum pressure (Pmax) that the superhydrophobic cylinders could hold when the fluid inside the channel was under static equilibrium. Finally, a self-regulated fluid delivery system was postulated based on the experimental and theoretical findings. [ABSTRACT FROM AUTHOR]

In this research, a low mole ratio formula Li to Zr of Li0.5xLa0.5xZr1−xO12−δ(LLZO*) with various x = 0.1, 0.3, and 0.6 was synthesized. The research aims to understand the crystal structure and the electrochemical properties of the new formula of Li0.5xLa0.5xZr1−xO12−δ, in which the Li to Zr mole ratio is smaller than the common cubic garnet of Li7La3Zr2O12 (LLZO). A different sintering treatment was also applied to understand whether the material properties are only a matter of chemical formula or are also affected by the sintering method. The first sintering method was firing at 1230 °C for 6 h under air to produce LLZO*(A), and the second method was firing at 900 °C for 6 h under Ar flows to produce LLZO*(B). The XRD analysis found that the LLZO*(A) was crystallized mainly to tetragonal structure, and cubic pyrochlore secondary phase, with a small amount of cubic structure. Meanwhile, the LLZO*(B) was crystallized mainly into cubic and tetragonal structure. The impedance analysis found that LLZO*(B) shows a higher ionic conductivity than LLZO*(A), i.e., 7.573 × 10−5 S.cm−1. A full-cell impedance measurement of LiFePO4-LLZO*(B)-mcmb shows that LLZO*(B) x = 0.1 has the lowest Li+ migration resistance of 223.8 Ω confirming the promising material for solid electrolyte. [ABSTRACT FROM AUTHOR]