Innovation of Hydrothermal Synthesis from the Past and Present

620 WordsFeb 20, 20182 Pages
INNOVATION OF HYDROTHERMAL SYNTHESIS FRON THE PAST & PRESENT Traditional Hydrothermal Synthesis since the end of the 19th century, hydrothermal synthesis of inorganic materials has been carried out. It is defined as the precipitation of these materials from aqueous solutions at temperatures above the boiling point and at pressures greater than ambient pressure. This method is actually environmentally because it does not require any organics or additional processing such as calcinations. That is the reason why it has been widely used for synthesis of a wide range of materials especially metal oxides such as hematite and quartz. Hydrothermal synthesis of quartz was demonstrated several decades ago and now currently used commercially. The traditional hydrothermal synthesis method is carried out in an autoclave type reactor where an aqueous solution is heated slowly to a certain temperature and then aged for several hours or days. In the case of the formation of metal oxides, hydrothermal synthesis method is generally involve two reactions which are hydrolysis of the meal salts followed by dehydration. M(NO ) x + xH O = M(OH) x + xHNO (Hydrolysis) H O x M OH x MOx / 2 2 2 ( ) = + (Dehydration) This method is normally at around 373-473 K. During the heat-up period, the above reactions take place to produce nuclei and eventually crystals. During hydrothermal reactions resulting in materials with the desired microstructure and properties, the homogeneous nucleation and grain

More about Innovation of Hydrothermal Synthesis from the Past and Present

Open Document