Narrow Results

Exploring the morphogical and structural properties along with gas sensing applications both pure and Ti-doped SnO₂ ultra-thin films, were meticulously crafted on micromachined silicon substrate heater devices using a combination of classical soft chemical processes and hydrothermal techniques (SCPHTP). The fabrication process involved a two-step approach: initially, a 20nm layer of tin oxide was hydrothermally deposited onto the substrates, followed by annealing in wet air at 600^∘C for 5h using a standardized temperature variation protocol. Subsequently, secondary layers with thicknesses of 20, 40 and 60nm were sequentially deposited onto the tin dioxide devices and oxidized in wet air at 550^∘C and 600^∘C for 20h each, using the same temperature modulation scheme. Throughout this process, the hydrothermal deposition temperature remained constant at 180^∘C for both the initial and secondary layers of tin dioxide deposition. Additionally, Ti layers with thicknesses of 4 and 8nm were deposited onto the 20nm + 40nm system, subjected to annealing at 550^∘C for 20h, followed by 1-min annealing in dry O₂ at 700^∘C and 800^∘C, respectively, using a Rapid Thermal Annealing (RTA) system. Characterization of the crystalline and surface structures of the devices revealed a transformation of the soft chemical tin dioxide solution into the cassiterite structure of SnO₂, resulting in uniform large surface areas for the sensor devices. Moreover, Ti metal layers of 4 and 8nm thicknesses were fully converted into TiO₂ on the surface of the devices. Subsequent testing showcased higher current values in sandwich systems of 20nm + 60nm and 20nm + 40nm compared to the 20nm + 20nm configuration. Sensitivity and stability assessments for various volatile organic compounds (VOCs) and CO gases at a constant DC temperature of 400^∘C indicated excellent performance, with sensitivity to CO gas being contingent on relative humidity (RH). Notably, RTA-annealed and Ti-8 nm-doped sensor devices exhibited superior sensitivity and reproducibility, particularly when treated at 800^∘C in dry O₂ for 1min. This heightened performance can be attributed to the occupation of chloride ions in the oxygen sites of the as-synthesized SnO₂, resulting in enhanced sensing capabilities for VOC gases.

Anatase Ti_1-xCo_xO₂ nanoparticles were prepared by a hydrothermal process at 180 °C. Ferromagnetic hysteresis loops of the as-prepared samples were measured at room temperature. The Ti_1-xCo_xO₂ (x = 0.0376) powder shows coercivity up to 700 Oe, which is the highest value reported for anatase Ti_1-xCo_xO₂. X-ray diffraction (XRD), transmission electron microscopy (TEM) and magnetic measurement results provided evidence that Co was incorporated into TiO₂ lattice. Combined with the fact that the preparation was carried out in an oxidized environment starting from cobalt (II) in the oxidized state, it is suggested that the homogeneous doping of Co into the lattice of anatase should be responsible for the improvement of coercivity in anatase Ti_1-xCo_xO₂ nanoparticles.

Boron nitride nanocrystals have been prepared in a hydrothermal route. The crystalline phases have been identified as cubic boron nitride (cBN) and orthorhombic (oBN) by XRD and FTIR. Further evidences for the formation of cBN have been obtained from microanalysis and composition identification by HRTEM, SAED and EDS.

Nanocrystal MnO₂ was successful synthesized by hydrothermal method under pulsed magnetic field. The effect of pulsed magnetic field on the nucleation and growth of MnO₂ was studied by XRD and SEM analysis. It was found that the morphology of MnO₂ has been changed comparing without magnetic field. However, there were no different phases presented when pulsed magnetic field was applied.

Single crystalline hydroxyapatite nanorods (HAp-NRs) were synthesized using a simple hydrothermal method. The synthesized HApNRs have an aspect ratio of about 8-10. A closer inspection of the nanostructure of a single nanorod revealed a highly regular and defect-free lattice with unique crystallographic plane orientations. X-ray Diffraction (XRD) pattern shows the highly crystalline nature of the product. The Field Emission Scanning Electron Microscopic (FESEM) image shows the uniform size distributed rod like morphology of length 100-150nm and diameter of about 15-20nm. Transmission Electron Microscopic analysis (TEM) and High-Resolution TEM (HRTEM) images provide further insight into the microstructure and morphology of the product. The selected area electron diffraction (SAED) pattern confirms that the nanorods are single crystal in nature. The mechanical strength of hydroxyapatite was studied by reinforcing hydroxyapatite with High Molecular Weight Polyethylene (HMWPE). It clearly shows that the mechanical properties of the nanorods are high when compared to that of bulk HAp. Finally the composites were characterized by means of thermal analysis including thermogravimetry analysis and differential thermal analysis (TGA-DTA) in order to study the thermal stability of the composite and the effect of filler in HMWPE.

In this paper, a newly designed composite of magnetic nano-Co₃O₄ fiber coated on carbon fiber (Cf) is prepared and characterized for the electromagnetic interference (EMI) shielding properties. XRD, SEM and TEM are used to investigate the micromorphology and microstructure evolution during the preparation. By hydrothermal method, the flowerlike clusters of single crystal flake-Co(OH)₂ are first obtained on Cf. The firstly prepared Co(OH)₂ sheets then turn into Co₃O₄ fibers during the next calcination step. The continuous and loose coating of magnetic Co₃O₄ nanofibers is finally obtained on the Cf. The loose coating is in proportion to the weight loss, and the wirelike Co₃O₄ is good for the interface strength for the Cf composite preparation. Based on the above work, the loose magnetic fibers coating on the Cf could be a feasible composite structure for the EMI composite materials integrated with absorbing and reflecting.

In this study, the preparation of ternary photocatalyst using a simple hydrothermal method is shown with high performance. A ternary composite consisting of tungsten sulfide (WS${}_2)$ nanosheets, titanium oxide (TiO${}_2)$ and gold (Au) nanoparticles is used to the extend the visible-light absorption region of TiO₂. The morphological and spectroscopic natures of the prepared sample were analyzed using scanning electron microscopy (SEM), Raman spectroscopy and ultraviolet–visible (UV–vis) photospectroscopy. The photocatalysis measurement for photodegradation of methylene blue dye was performed under the visible light. The photocatalytic studies suggest that in the ternary composite, consisting of three materials with different energy levels, the electrons excited form a cycle to lower the probability for the recombination of electron–hole pairs enhancing the property of photocatalytic activity of TiO₂.