A solvothermal process can be defined as a process in a closed reaction vessel inducing a decomposition or a chemical reaction(s) between precursor(s) in the presence of a solvent at a temperature higher than the boiling temperature of this solvent. The pressure can be autogeneous (in such a case the pressure value depends on the filling of the reaction vessel) or imposed (the pressure value be...

Thermodynamic calculations showed that the autotrophic synthesis of all 20 protein-forming amino acids was energetically favored in hot (100 degrees C), moderately reduced, submarine hydrothermal solutions relative to the synthesis in cold (18 degrees C), oxidized, surface seawater. The net synthesis reactions of 11 amino acids were exergonic in the hydrothermal solution, but all were endergoni...

a hydrothermal method for preparation of nano-size zirconia has been studied to optimize the effective parameters (precursor concentration, temperature and time) using response surface methodology (rsm). the synthesized zirconia samples were characterized through x-ray diffraction (xrd), scanning electron microscope (sem) and transmission electron microscopy (tem) analyses to identify mean nano...

This study presents experimental results dealing with the possibility of transforming F-class fly ash into a zeolitic material. Two types of synthesis methods were used in the research: hydrothermal and low-temperature synthesis. As a result of alkaline reaction of fly ash with NaOH, all experimental cases yielded zeolitic material that are rich in a Na-X phase. The mineralogical composition (d...

Two new manganese(II) selenite polymorphs with formula Mn(SeO3) have been synthesised using supercritical hydrothermal conditions. The crystal structure of both compounds (1) and (2) has been solved from single-crystal X-ray diffraction data. The structures consist of a three-dimensional framework formed by MnO6 octahedra and (SeO3)2- selenite anions with trigonal pyramidal geometry. Compound (...

in the present work, the effect of ca(no3)2.4h2o and (nh4)2hpo4 primary solutions as the beginning materials in synthesis of a calcium phosphate phase, was examined. so, we investigated the wet chemical reactions in solution at different temperatures by a hydrothermal condition aimed at hydroxyapatite (ca10(po4)6(oh)2); (hap) synthesis. the powders were investigated by xrd,sem, fe-tem, hrtem, e...

Miniaturized accelerometers are necessary for evaluating the performance of small devices, such as haptics, robotics and simulators. In this study, we fabricated miniaturized accelerometers using well-aligned ZnO nanowires. The layer of ZnO nanowires is used for active piezoelectric layer of the accelerometer, and copper was chosen as a head mass. Seedless and refresh hydrothermal synthesis met...

With high pressures, supercritical fluids can be studied over a very wide range of density. Fluids with strongly interacting polar molecules for example water are of particular interest. Results for several thermophysical properties are discussed. Density, dielectric constant and self—ionization of water have been determined or predicted to 1000 °C. Beyond 20 GPa very hot water appears to becom...

The structure and properties of supercritical water is investigated in relation to the energy and environmental issues of the 21 century. Molecular interpretations are given to the temperature dependence of the hydrogen-bonding structure, dynamics, and chemical reactions of supercritical water. The three-dimensional network structure, characteristic of ambient water, is broken down in hot expan...