Hydrothermal Synthesis Research Papers - Academia.edu (original) (raw)

Crystals of LTA zeolites were obtained in absence of organic templates using a crystallization temperature of 373 K. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-Transform Infrared (FTIR) spectroscopy. The aging time was found to be a crucial factor for the control of the crystal size. Samples aged between 72 and 144 h presented an

- by salvador alfaro
- •
- Engineering, Crystal Growth, FTIR spectroscopy, Scanning Electron Microscopy

Magnesium borate hydroxide (MBH) nanowhiskers were synthesized using a one step hydrothermal process with different surfactants. The effect surfactants have on the structure and morphology of the MBH nanowhiskers has been investigated. The X-ray diffraction profile confirms that the as-synthesized material is of single phase, monoclinic MgBO2(OH). The variations in the size and shape of the different MBH nanowhiskers have been discussed based on the surface morphology analysis. The annealing of MBH nanowhiskers at 500 °C for 4 h has significant effect on the crystal structure and surface morphology. The UV–vis absorption spectra of the MBH nanowhiskers synthesized with and without surfactants show enhanced absorption in the low-wavelength region, and their optical band gaps were estimated from the optical band edge plots. The photoluminescence spectra of the MBH nanowhiskers produced with and without surfactants show broad emission band with the peak maximum at around 400 nm, which confirms the dominant contribution from the surface defect states.

- by Latha Kumari
- •
- Materials Engineering, Condensed Matter Physics, Nanotechnology, Crystal structure
- by Andrea Katovic
- •
- Engineering, Kinetics, Sample Preparation, Iron

Nanosized zirconium oxide (ZrO2) powders were prepared by adding NaOH to a zirconyl chloride aqueous solution under microwave-hydrothermal conditions. The obtained results showed that the tetragonal polymorph increased with increasing NaOH concentration in the starting solution and reached the maximum value by using 1M ZrOCl2. The microwave-assisted hydrothermal synthesis is expected to be able to process continuously, and may lead to energy savings because of rapid heating to temperature and increased kinetics of crystallization. This method is very simple and can lead to powders with desirable characteristics such as very fine size, narrow size distribution, and good chemical homogeneity.

- by Federica Bondioli
- •
- Materials Engineering, Mechanical Engineering, The, Hydrothermal Synthesis
- by Cristina Leonelli
- •
- Materials Engineering, Mechanical Engineering, The, Hydrothermal Synthesis
- by Gérard Férey
- •
- Inorganic Chemistry, Organic Chemistry, Fluorine Chemistry, Chromium
- by Begona Bazan
- •
- Inorganic Chemistry, Solid State Chemistry, Crystal structure, X Rays
- by Colette Boskovic and +1
- •
- Inorganic Chemistry, Old Copper Complex, Copper, Magnetic Properties
- by Suresh Waghmode
- •
- Engineering, Magnesium, Molecular Sieve, CHEMICAL SCIENCES
- by Petra Jongh
- •
- Engineering, CHEMICAL SCIENCES, Hydrothermal Synthesis, Aspect Ratio

Aluminum doped zinc oxide (AZO) nanometric particles were synthesized by hydrothermal method. Aluminum nitrate hydrate, aluminum sec-butoxide and zinc nitrate hydrate were used as the starting materials, and n-propanol and 2-butanol were used as solvents. Ratio of Al2O3 in ZnO was kept at 10 wt%. Reaction was conducted in a Teflon autoclave at 175–225 °C for 5 h. Ratios of alcohol, H2O and HCl to zinc nitrate hydrate were altered and 6 different sets of parameters were investigated. Obtained products were subjected to powder-XRD, particle size measurement, TEM examination and AAS analysis. Single phase AZO particles were obtained at alcohol to zinc nitrate ratio of 35, acid to zinc nitrate ratio of 0.2, at 225 °C. Particle size was determined as 3.2 ± 0.4 nm from TEM examinations and as 1–2 nm from dynamic light scattering. Synthesized particles have amphiphilic character, thus they can be dispersed in both polar and non-polar media. It was seen from the UV-diffuse reflectance spectra that the AZO powder had low reflectance in the UV region and high reflectance in the visible region. The obtained powder has the potential to be utilized in the form of thin films for optical and electronic purposes.

- by Chuanhui Gao and +1
- •
- Chemical Engineering, Kinetics, Transmission Electron Microscopy, Magnesium

Nickel doped zinc oxide (Ni/ZnO) nanostructures have the potential to improve the performance of electrochemical capacitors. This study investigates the preparation of Ni/ZnO nanomaterials by facile co-precipitation (CPM) and hydrothermal (HTM) methods. The effect of the synthesis methods on the optical, structural, chemical and morphological properties on ZnO products is investigated using ultra violet (UV)-visible spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray spectrometry (EDX), room temperature photoluminescence (PL), Fourier transform infrared (FTIR) and Raman spectroscopy. Finally, the electrochemical performance of the synthesized nanorods were examined by fabrication of a supercapacitor using standard three electrode cell configuration and tested with a cyclic voltammogram (CV) and galvanostatic charge-discharge (GCD) measurements. The results shown that the samples synthesized by HTM exhibited improved electrochemical capacitance performance with higher current density. The discharge curves are linear in the total range of potential with constant slopes, showing perfect capacitance. In conclusion, Ni/ZnO nanoparticles synthesized by this method with further optimization have the potential to lead to a high-efficiency supercapacitors.

- by Joshua Pearce and +1
- •
- Materials Engineering, Materials Science, Chemistry, Thin Films and Coatings
- by Juewen Liu
- •
- Materials Engineering, Materials, Crystal structure, Transition-Metal Oxides

Cadmium sulfide (CdS) one dimensional (1D) nanocrystals were prepared using a polyethylene glycol (PEG) assisted hydrothermal synthesis. X-ray diffraction result confirms that the nanorods are of hexagonal structure and the selected area electron diffraction (SAED) identifies the single crystalline nature of the sample. The sample was systematically characterized by UV-vis absorption, photoluminescence (PL) spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermal analysis. The UV-vis absorption spectrum indicates the narrow size distribution of the CdS nanorods. The absorption band edge is seen shifted to 505 nm than the bulk material and the corresponding band gap is found to be 2.45 eV. The PL emission peak is detected around 550 nm. From SEM and EDX analysis, the morphology of the aggregates and the composition of the obtained product are identified. The TEM micrographs indicate that the CdS nanorods exhibit well defined morphology and high crystalline quality with narrow size distribution of lengths and widths. The TG/DTA traces of the nanopowder show four major stages of weight loss.

- by Akshay Jain
- •
- Biomass, Activated Carbon, Hydrothermal Synthesis

Over the last 25 years, the gem industry has seen an increasing number of reports by associates and laboratories indicating a tremendous proliferation of synthetic quartz at all levels of the market. The stones reported were most often of the finest colors and with excellent clarity, often eye-clean. In recent years, there has been more material seen in colors without a natural counterpart.

- by Guy Borenstein
- •
- Gemology, Mineralogy, Quartz, fluid Inclusions

A B S T R A C T The aim of this study was to test the diatomaceous earth from a deposit near Rožden Village (Macedonia) as a raw material for low temperature hydrothermal production of porous ceramics. Hydrothermal synthesis of porous ceramics has been carried out under saturated steam pressure at 130 °C for a period of 1, 2 and 3 h. The objective of this work was to investigate the impact of slaked lime, autoclave curing time, autoclaving temperature and compaction pressure on the compressive strength and porosity of the products. During the hydrothermal synthesis, newly obtained calcium silicate hydrate dominates which give positive effect to the compressive strength and product porosity confirmed by X-ray powder diffraction. Moreover, a calcite was also evidenced by FTIR spectroscopy whose presence additionally increases the compressive strength of the hydrothermal products. The products obtained during the low-temperature hydrothermal reaction are classified as light porous ceramics with bulk density ranging from 0.71 to 0.91 g/cm 3 and compressive strength within 14.7–19.4 MPa.

- by Arianit Reka
- •
- Ceramic Engineering, Ceramic Technology, Ceramics (Ceramics), Porous Materials
- by Akshay Jain
- •
- Activated Carbon, Hydrothermal Synthesis
- by Q Li
- •
- Materials Engineering, Zirconia, Hydrothermal Synthesis
- by Santhosh K Matam
- •
- Chemical Engineering, Catalysis, Iron, Hydrothermal Synthesis

Highly crystalline TiO2 nanostructures were prepared through a facile inorganic acid-assisted hydrothermal treatment of hexagonal-structured assemblies of nanocrystalline titiania templated by cetyltrimethylammonium bromide (Hex-ncTiO2/CTAB Nanoskeleton) as starting materials. All samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The influence of hydrochloric acid concentration on the morphology, crystalline and the formation of the nanostructures were investigated. We found that the morphology and crystalline phase strongly depended on the hydrochloric acid concentrations. More importantly, crystalline phase was closely related to the morphology of TiO2 nanostructure. Nanoparticles were polycrystalline anatase phase, and aligned nanorods were single crystalline rutile phase. Possible formation mechanisms of TiO2 nanostructures with various crystalline phases and morphologies were proposed.

- by PDMS PMMA
- •
- Microstructure, Biomaterials, Nanobiotechnology, Treatment
- by Marc Henry
- •
- Chemistry, CHEMICAL SCIENCES, Structure Elucidation, Hydrothermal Synthesis
- by Akshay Jain
- •
- Activated Carbon, Hydrothermal Synthesis
- by Stanislav Ferdov
- •
- Engineering, Kinetics, Potassium, CHEMICAL SCIENCES
- by José Luis Pizarro
- •
- Chemical Engineering, Inorganic Chemistry, Arsenic, Inorganic
- by Fernando Rizzo and +1
- •
- Condensed Matter Physics, Inorganic Chemistry, Polymorphism, Transmission Electron Microscopy
- by Shiau-Wu Lai
- •
- Hazardous Materials, Nitrogen, UV/Vis spectroscopy, High Temperature
- by Giuseppina Meligrana and +1
- •
- Engineering, Performance, Scanning Electron Microscopy, Surfactant
- by Mugera Gitari
- •
- Acid Mine Drainage, Ion Chromatography, Multidisciplinary, Elasticity
- by Akshay Jain
- •
- Supercapacitors (Chemistry), Activated Carbon, Hydrothermal Synthesis
- by Rodrigo Parra
- •
- Engineering, Raman Spectroscopy, Titanium, Ceramics
- by Darja Lisjak and +2
- •
- Materials Engineering, Mechanical Engineering, Hydrothermal Synthesis
- by Elena Brusau
- •
- Inorganic Chemistry, Hydrothermal Synthesis
- by Anna Maria Ferrari
- •
- Engineering, Materials Engineering, Mechanical Engineering, Microwave

A study was carried out on the production of CuAlO2 by using 3 different production routes namely, hydrothermal synthesis, conventional solid state reaction and electrospinning process. For hydrothermal synthesis, commercially available metal salts, Cu2O powder and chemically precipitated CuO nanoparticles were used as precursors. Bulk CuAlO2 samples were prepared via solid state reaction route by ball milling and high temperature sintering of CuO and Al2O3 powders. CuAlO2 ceramic mats were synthesized by electrospinning process with the assistance of polyvinylpyrolidone, as a template polymer. Highly crystalline mesh structured fibers were obtained after sintering of polymer/equal moles of copper chloride and aluminum nitrate composite in air. In the current work, solid state reaction and electrospinning processes yielded phase pure CuAlO2 in hexagonal symmetry. On the other hand, products obtained from hydrothermal synthesis were CuO, Cu2O and Al(OOH), which did not yield CuAlO2 under current experimental conditions. Detailed qualitative X-ray diffraction analysis revealed the need of specific ionic species in the solution within a narrow temperature-composition-pH window to obtain phase pure CuAlO2 employing hydrothermal conditions.

- by Volkan Kalem and +4
- •
- Electrospinning, Hydrothermal Synthesis, Transparent Conducting Oxides, Solid State Reaction

New, blue-emitting phosphors were sought among the family of borosilicates as possible new phosphor
hosts. Ca1xEuxB2Si2O8 with the danburite structure could be synthesized at 800 1C and 140 MPa
pressure under hydrothermal conditions. This host material could be activated by Eu2þ to produce a
blue emitting phosphor with an emission peak close to the desired value of 450 nm, and chromaticity
coordinates close to the published NTSC values for the blue standard.

- by Hassan Al-Juwhari
- •
- Rare Earth, Hydrothermal Synthesis, Phosphors, Borosilicates

Although the Bi 2 S 3 QDs have an ideal bandgap for the efficient light absorbers, the Bi 2 S 3 QDs sensitised solar cells generally indicate low photovoltaic properties owing to the active photocorrosion of Bi 2 S 3 QDs. Herein, we report the enhancement of Bi 2 S 3 QDs sensitised solar cells using the co-sensitisation of Bi 2 S 3 with CdS QDs. By the homogeneous covering as well as effective blocking of photocorrosion and recombination, the CdS/Bi 2 S 3 co-sensitised solar cells showed threefold increase in efficiency.. (2016) 'Enhancing Bi 2 S 3 sensitised mesoporous TiO 2 solar cells by co-sensitisation with Bi 2 S 3 /CdS quantum dots',

- by Alagappan Annamalai
- •
- Renewable Energy, Solar Cell, Nanotechnology, Quantum Dots
- by P. Sagayaraj
- •
- Engineering, Materials Engineering, Technology, Materials Chemistry

A detailed Móssbauer investigation of magnetites prepared under different hydrothermal
conditions and doped with Cu and Cr is presented. The samples were characterized by
means of room temperature Móssbauer spectrometry, infrared spectroscopy, and X-ray
diffraction. Móssbauer results show that the hydrothermal method produces highy
stoichiometric and relativelly well-crystallized magnetites. The results suggest that the best
samples are obtained when the alkaline solution is added quickly to the ferrous solution. It
was also found that mixing the solutions under constant ultrasonic stirring produce
magnetites with slightly better crystallinity and stoichiometry than the samples produced
under magnetic or nitrogen bubbling stirring. The effect of the Cu and Cr on the hyperfine
parameters is also presented and discussed.

- by Paula Montoya
- •
- Hydrothermal Synthesis, Magnetite, Corrosion Products
- by Pramod Borse
- •
- Materials Engineering, Chemical Engineering, Surface Area, Hydrothermal Synthesis
- by Artur Ferreira
- •
- Engineering, Scanning Electron Microscopy, Titanium, X Rays
- by Pavel Shuk
- •
- Materials Engineering, Condensed Matter Physics, Thermodynamics, Electron Microscopy
- by R. Piticescu
- •
- Materials Engineering, Thermodynamics, Kinetics, Ionic Conductivity