Papers by Keyword: Hydrothermal

Abstract: The cubic and rod-shaped powders of indium tin oxide were synthesized at a stable temperature reaction for 18h using the surfactant aid hydrothermal method under various conditions. The cubic and rod-shaped powder size changes with the concentration of the precursor. The finished products of indium tin oxide can be obtained by calcination at 500°C for 2h in air. Characterization was conducted using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffractometry (XRD), thermogravimetric analyzer/differential thermal analysis (TG/DTA) and the Brunauer-Emmett-Teller (BET). XRD analysis shows that the conditions of this experiment can produce pure ITO powders. The characterization of cubic and rod-shaped ITO powders is also discussed.

Abstract: This study has focused on mesoporous silica nanoparticles as a drug delivery system of insulin, which was synthesized via a hydrothermal process. The morphology and composition of the silica nanoparticles were characterized by different analytical techniques such as Scanning Electron Microscope (SEM), X-Ray Diffraction Analysis (XRD), Fourier Transform Infrared spectroscopy (FTIR) and BrunauerEmmettTeller (BET). The percentage of drug loading and the in vitro drug release properties of the mesoporous silica nanoparticles in gastrointestinal tract were investigated in simulated gastrointestinal conditions by ultraviolet-visible spectroscopy. The results showed the amorphous structure of SBA-15 in mesoporous silica particles has a narrow pore size distribution. Also, particles shape was nearly wheat-like with almost homogeneous size distribution. Furthermore, it was revealed that the mesoporous silica nanoparticles have a high insulin loading and release capacity. These prominent behaviors make mesoporous silica nanoparticles promising material as a drug carrier for insulin delivery.

Abstract: The purpose of this work is to provide a comparative study of polyacrylic acid alumina (PAA/Al2O3) bulk composites with PAA/Al2O3 nano composites. This work also provides a study in the variation of glass transition temperature due to the doping of metal. Alumina nano particles were prepared using hydrothermal method. This sample was doped with Cu. Polyacrylic acid alumina nano composites were prepared using two different methods. The alumina samples were added to acrylic acid. In the first method the mixtures of acrylic acid and alumina samples were heated in oven. In the second method the same mixtures were irradiated with microwaves. The samples prepared were allowed to cool down and dried. Also the alumina bulk particles were also dispersed in acrylic acid and the similar procedure was carried out. The effect of preparation methods on the glass transition temperature of PAA/Al2O3 and PAA/Al2O3 nano composites have been studied. The glass transition temperatures Tg were determined using DSC analysis.

Abstract: The ZnO nanorods were prepared at 130 °C, 160 °C and 190 °C for 6 h by hydrothermal method. The structural and optical properties of ZnO nanorods were invesitigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). XRD pattern analysis showed that the ZnO nanorods are the hexagonal structure (space group P63 mc). No other crystal phases, such as Zn and Zn (OH)₂ were detected. FT-IR study identified the sharp peak that appeared at 573 cm^-1 is related with the ZnO stretching mode. Also, SEM images revealed that the diameter of a single ZnO crystal ranges from 100 to 300 nm and the length ranges from 1 to 3 μm.

Abstract: In this paper, we demonstrated the acicular-like ZnO nanostructure powder were prepared by hydrothermal method. We used the industrial aerosol elemental zinc powders through high energy ball mill, and then took ball mill zinc powder into autoclave reactor direct synthesis high length to diameter ratio of acicular-like ZnO nanostructure powder. The samples phase were studied by XRD, the morphology of the sample were observed by SEM, the samples of luminous performance were studied by Fluorescence spectrophotometer. When the hydrothermal temperature is 200°C, hydrothermal time is 24 h, mineralizer of NaOH concentration is 1 mol/L, the samples were washed by alcohol and then dried at 80°C for 3 hours. We had synthesized the high dispersion, high length to diameter ratio up to 50 acicular-like ZnO nanostructure powder.

Abstract: Hydrothermal method was used to prepare Ce doped ZnO. Effects of doping ratio, reaction time, reaction temperature, filling degree on the flower-like morphology of ZnO were studied. And the phase, morphology and size of the products were characterized by XRD and SEM. The vector network analyzer was used to characterize the products electromagnetic performance. The results show that, Ce is successfully doped into the lattice of ZnO. The products maintain perfect flower-like structure when Ce:ZnO (molar ratio) is 0.5%. However, the flower-like morphology is damaged more and more obviously with the doped concentration increasing. The crystal growth rate accelerates with reaction temperature increasing. Microwave absorbing properties of ZnO can be improved greatly by doping Ce. The reflection loss is more than 10dB when the frequency between 9.8 GHz and 11.6GHz.

Abstract: The Bi₂WO₆ three-dimensional (3D) hierarchical microspheres from nanoplates have been synthesized by a hydrothermal route. The products were characterized in detail by multiform techniques: X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDS), scanning electron microscopy (SEM), and UVVis absorption spectrum. XRD patterns indicated that the Bi₂WO₆ three-dimensional hierarchical microspheres were orthorhombic phase. Furthermore, SEM revealed that Bi₂WO₆ three-dimensional hierarchical microspheres consisted of Bi₂WO₆ nanoplates.

Abstract: Tungsten trioxide (WO₃) nanostructure with aspect ratio of 20 (length/diameter) have been successfully synthesized by single step hydrothermal reaction at moderate temperature of 180 °C. The crystal structure and morphology evolution are characterized by SEM and Raman while the carbon dioxide (CO₂) sensing capability was tested by simple sensor fabrication .It was observed that the nanorods were initially coalesce in bundles before breaking up loosely towards the end of the hydrothermal process. A response measurement reveals that the sensor was able to detect CO₂ at room temperature with the sensitivity around 13ohm/100 ppm. The detection performance of such nanostructure provides a positive indication that it can be a competitive sensor element candidate not only for CO₂ applications in particular but can be expanded to other gas sensing application such as O₂, C₂H₄ and NO₂.

Abstract: A facile synthesis route for monodispersed lead zirconate titanate (PZT) nanoparticles was developed by simple hydrothermal reactions under the assistance of polymer blend including polyvinylalcohol (PVA) and polyacrylate acid (PAA). It was found that PZT particles with an average size of 2.6 nm as well as a very narrow size distribution could be obtained with a 19.0 g/L polymers solution under a low KOH concentration of 2 mol/L at 200 °C for 14 h, indicating that the polymer additives played an important role in controlling the morphology and size of PZT crystals. The simple polymer-assistant hydrothermal synthesis is feasible for the mass production of PZT nanoparticles and is expected to be used in the miniaturization of electronic devices.

Abstract: A simple synthesis route to high-quality ZnO nanorod is reported, utilizing ZnO thin films grown by Filtered Pulse Cathodic Vacuum Arc (FPCVA) deposition as seed layers and continuous growth by hydrothermal method. Depending upon the FPCVA deposited conditions, implanted voltages, thickness and annealing temperature of ZnO seed layer, the surface morphology of the ZnO nanorod on ZnO film was noticeably different. The average diameters of the nanorod on Al substrates varied from about 131.99 ± 23.87 to 418.17 ±75.50 nm. The grown ZnO nanorod showed a high crystallinity with energy gap of 3.37 eV and low defect density confirmed by UV/VIS Spectrometer and photoluminescence spectrum (PL). Large-area growth, quasi-aligned and high quality indicates that the ZnO nanorods produced have potential application in field emission and optoelectronic devices.