Papers by Keyword: Hydrothermal Technique

Abstract: Zinc stannate (ZTO) NPs were prepared hydrothermal for 20 hours at 200 ᵒC. Structural, morphological, and optical properties of the ZTO NPs were studied for different zinc salt types (ZnSO₄.7H₂O, Zn(CH₃COO)₂.2H₂O, and Zn (NO₃)₂•6H₂O). The X-ray diffraction studies showed the crystalline nature with a spinel crystal structure of the ZTO nanostructure. FE-SEM image showed spherical morphology with the formation of a network of aggregates. The transmittance spectra were recorded at wavelengths ranging from 200 nm to 1200 nm. In particular, their optical band gap energies were 3.65, 3.85, and 3.8 eV for three zinc salts of ZTO (ZnSO₄.7H₂O, Zn(CH₃COO)₂.2H₂O, Zn (NO₃)₂.6H₂O), respectively. The MIC showed the ZTO NPs for zinc salt ZnSO₄.7H₂O in Volumetric dilution 3.125% and 12.5 was more effective against Escherichia coli and Staphylococcus aureus from another zinc salt of ZTO NPs. Inhibition Zone assessed ZTO NPs' antibacterial efficacy against Staphylococcus aureus and Escherichia coli. With three concentrations of ZTO, the test showed that ZTO NPs have a stronger antibacterial activity against gram-positive bacteria than gram-negative bacteria. The antibacterial activity of zinc salt ZnSO₄.7H₂O was found to be 32 against Escherichia coli and 19 nm against Staphylococcus aurous, it was more effective than other zinc salt of ZTO NPs.

Abstract: The application of special nanomaterials is promising for the development of new methods for the diagnostics and treatment of cancer. Photodynamic therapy (PDT) is a well-known and recognized method of cancer treatment. This type of therapy is less carcinogenic and mutagenic compared to radiation and chemotherapy, since the applied photosensitizers do not bind to DNA of the cells. However, currently this technique is only applicable to skin cancer, while its extension to the treatment of abdominal tumors requires the creation of pharmacological drugs for PDT, which along with a photosensitizer include a colloidal solution of nanosized luminescent phosphor emitting visible light with the required wavelength under the influence of infrared, X-ray or γ-radiation, which easily penetrates the body tissues. Since photosensitizers are already available as commercial products, the most important goal is the development of nanosized phosphors providing the required radiation convertion. In this study, the effects of hydrothermal synthesis, duration and the conditions of rapid thermal annealing (RTA) on Y₂O₃:Eu phosphor particle size were studied. The hydrothermal synthesis technique was carried out in two ways: chloride (precipitation from a chloride solution using NaOH and NH₄OH precipitators) and acetate (decomposition of mixed acetate either without a dispersant at 230° C for 24 hours, or using PEG-200 and PEG-2000 as dispersants at 230 °C for 12 hours). The rapid thermal annealing was performed either at 600 °C for 20 minutes, or at 800 °C for 5 minutes. The developed synthetic approaches afforded Y₂O₃:Eu nanosized phosphor samples with the particle size not exceeding 200 nm.

Abstract: Anatase and rutile TiO₂ nanostructure have been successfully synthesized via CD reactive magnetron sputtering and hydrothermal synthesis followed by post-treatment from titanium powder. The morphology and crystalline structure of the nanostructure are characterized in detail with X-ray diffraction (XRD), Field Emissiom Scanning Electron Microscope (FE-SEM), Scanning Electron Microscope (SEM), energy dispersive X- ray and energy dispersive x-ray analyzer (EDX). The pattern showed anatase and rutile phase crystalline structure. The thin films showed the surface as viewed uniform tiny spots distribution. TiO2 nanostructures were successfully synthesized using a simple hydrothermal synthesis method from TiO2 nan_{Subscript text}oparticles. The samples were synthesized by means of the hydrothermal reaction of TiO₂ nanoparticle of anatase and rutile phase. In a typical procedure, The time were varied, and cooled to room temperature, naturally. The samples showed structures of crystalline, anatase and rutile phases. They were morphology TiO₂ nanorods, TiO₂ nanowires and TiO₂ nano shape with the diameters of about 30-300 nm. The EDX analysis of an area containing a large amount of TiO₂ nanostructure reveals the existence of Na, Ti and O elements.

Abstract: BaTiO3 (BT) nanoparticles were prepared by the hydrothermal technique using different starting materials and the microstructure examined by XRD, SEM, TEM and HRTEM. X-ray diffraction and electron diffraction patterns showed that the nanoparticles were the cubic BaTiO3 phase. The BT nanoparticles prepared from the starting materials of as-prepared titanium hydroxide and barium hydroxide have spherical grain morphology, an average size of 65 nm and a fairly narrow size distribution. A uniform diffraction contrast across each single grain is observed in the TEM images, and the clear lattice fringes (with d110 = 0.28 nm) observed in HRTEM images reveal that well-crystallized BT nanoparticles are synthesized by the hydrothermal method. The edges of the particles are very smooth, with no surface steps. BT nanoparticles with average grain size of 90 nm, synthesized using barium hydroxide and titanium dioxide as the starting materials, show surface facets. In this case a bimodal size distribution of large faceted and smaller particles is observed. Diffraction contrast variation across the particles caused by high strains within the particles is clearly observed. The high strains obviously stem from structural defects formed during hydrothermal synthesis, presumable in the form of lattice OH− ions and their compensation by cation vacancies. HRTEM images demonstrate that surface facets parallel to the (100) and (110) planes and small islands with 3 ~ 4 atomic layer thickness are frequently observed around the edge of the particles.