Mechanically Robust Interface at Metal/Muscovite Quasi van der Waals Epitaxy.

Quasi van der Waals epitaxy is an approach to constructing the combination of 2D and 3D materials. Here, we quantify and discuss the 2D/3D interface structure and the corresponding features in metal/muscovite systems. High-resolution scanning transmission electron microscopy reveals the atomic arrangement at the interface. The theoretical results explain the formation mechanism and predict the mechanical robustness of these metal/muscovite quasi van der Waals epitaxies. The evidence of superior interface quality is delivered according to the outstanding performance of the designed systems in both retention (>105 s) and cycling tests (>105 cycles) through electromechanical measurements. With high-temperature X-ray reciprocal space mapping, the unique anisotropy of thermal expansion is discovered and predicted to sustain the thermal stress with a sizable thermal actuation. A maximum bending curvature of 264 m-1 at 243 °C can be obtained in the silver/muscovite heteroepitaxy. The electrothermal and photothermal methods show a fast response to thermal stress and demonstrate the interface robustness.

Bicontinuous oxide heteroepitaxy with enhanced photoconductivity.

Self-assembled systems have recently attracted extensive attention because they can display a wide range of phase morphologies in nanocomposites, providing a new arena to explore novel phenomena. Among these morphologies, a bicontinuous structure is highly desirable based on its high interface-to-volume ratio and 3D interconnectivity. A bicontinuous nickel oxide (NiO) and tin dioxide (SnO2) heteroepitaxial nanocomposite is revealed here. By controlling their concentration, we fabricated tuneable self-assembled nanostructures from pillars to bicontinuous structures, as evidenced by TEM-energy-dispersive X-ray spectroscopy with a tortuous compositional distribution. The experimentally observed growth modes are consistent with predictions by first-principles calculations. Phase-field simulations are performed to understand 3D microstructure formation and extract key thermodynamic parameters for predicting microstructure morphologies in SnO2:NiO nanocomposites of other concentrations. Furthermore, we demonstrate significantly enhanced photovoltaic properties in a bicontinuous SnO2:NiO nanocomposite macroscopically and microscopically. This research shows a pathway to developing innovative solar cell and photodetector devices based on self-assembled oxides.

Growth and Characterization of Sputtered InAlN Nanorods on Sapphire Substrates for Acetone Gas Sensing.

The demand for highly sensitive and selective gas sensors has been steadily increasing, driven by applications in various fields such as environmental monitoring, healthcare, and industrial safety. In this context, ternary alloy indium aluminum nitride (InAlN) semiconductors have emerged as a promising material for gas sensing due to their unique properties and tunable material characteristics. This work focuses on the fabrication and characterization of InAlN nanorods grown on sapphire substrates using an ultra-high vacuum magnetron sputter epitaxy with precise control over indium composition and explores their potential for acetone-gas-sensing applications. Various characterization techniques, including XRD, SEM, and TEM, demonstrate the structural and morphological insights of InAlN nanorods, making them suitable for gas-sensing applications. To evaluate the gas-sensing performance of the InAlN nanorods, acetone was chosen as a target analyte due to its relevance in medical diagnostics and industrial processes. The results reveal that the InAlN nanorods exhibit a remarkable sensor response of 2.33% at 600 ppm acetone gas concentration at an operating temperature of 350 °C, with a rapid response time of 18 s. Their high sensor response and rapid response make InAlN a viable candidate for use in medical diagnostics, industrial safety, and environmental monitoring.

Structure Effect on the Response of ZnGa2O4 Gas Sensor for Nitric Oxide Applications.

We fabricated a gas sensor with a wide-bandgap ZnGa2O4 (ZGO) epilayer grown on a sapphire substrate by metalorganic chemical vapor deposition. The ZGO presented (111), (222) and (333) phases demonstrated by an X-ray diffraction system. The related material characteristics were also measured by scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. This ZGO gas sensor was used to detect nitric oxide (NO) in the parts-per-billion range. In this study, the structure effect on the response of the NO gas sensor was studied by altering the sensor dimensions. Two approaches were adopted to prove the dimension effect on the sensing mechanism. In the first approach, the sensing area of the sensors was kept constant while both channel length (L) and width (W) were varied with designed dimensions (L × W) of 60 × 200, 80 × 150, and 120 ×100 µm2. In the second, the dimensions of the sensing area were altered (60, 40, and 20 µm) with W kept constant. The performance of the sensors was studied with varying gas concentrations in the range of 500 ppb~10 ppm. The sensor with dimensions of 20 × 200 µm2 exhibited a high response of 11.647 in 10 ppm, and 1.05 in 10 ppb for NO gas. The sensor with a longer width and shorter channel length exhibited the best response. The sensing mechanism was provided to explain the above phenomena. Furthermore, the reaction between NO and the sensor surface was simulated by O exposure of the ZGO surface in air and calculated by first principles.

High-Payload Data-Hiding Method for AMBTC Decompressed Images.

Data hiding is the art of embedding data into a cover image without any perceptual distortion of the cover image. Moreover, data hiding is a very crucial research topic in information security because it can be used for various applications. In this study, we proposed a high-capacity data-hiding scheme for absolute moment block truncation coding (AMBTC) decompressed images. We statistically analyzed the composition of the secret data string and developed a unique encoding and decoding dictionary search for adjusting pixel values. The dictionary was used in the embedding and extraction stages. The dictionary provides high data-hiding capacity because the secret data was compressed using dictionary-based coding. The experimental results of this study reveal that the proposed scheme is better than the existing schemes, with respect to the data-hiding capacity and visual quality.

NO gas sensor based on ZnGa2O4 epilayer grown by metalorganic chemical vapor deposition.

A gas sensor based on a ZnGa2O4(ZGO) thin film grown by metalorganic chemical vapor deposition operated under the different temperature from 25 °C to 300 °C is investigated in this study. This sensor shows great sensing properties at 300 °C. The sensitivity of this sensor is 22.21 as exposed to 6.25 ppm of NO and its response time is 57 s. Besides that, the sensitivities are 1.18, 1.27, 1.06, and 1.00 when exposed to NO2(500 ppb), SO2 (125 ppm), CO (125 ppm), and CO2 (1500 ppm), respectively. These results imply that the ZGO gas sensor not only has high sensitivity, but also has great selectivity for NO gas. Moreover, the obtained results suggest that ZGO sensors are suitable for the internet of things(IOT) applications.

Direct Observation of Sublimation Behaviors in One-Dimensional In2Se3/In2O3 Nanoheterostructures.

Recently, in situ transmission electron microscopy (TEM) has provided a route to analyze structural characterization and chemical evolution with its powerful and unique applications. In this paper, we disclose the detailed phenomenon of sublimation on the atomic scale. In2Se3/In2O3 nanowires were synthesized via the vapor-liquid-solid mechanism and studied in an ultra-high-vacuum (UHV) TEM at high temperature in real time. During in situ observation of the sublimation process of the nanowires, the evolution and reconstruction of the exposed In2Se3 surface progressed in different manners with time. The surface structure was decomposed by mass-desorption and stepwise-migration processes, which are also energetically favored processes in the ab initio calculation. This study developed a new concept and will be essential in the development of atomic kinetics.