Binary oxides powder sintering

The first review of sintered ceramics obtained starting with sol-gel oxide powders was presented by Devi and Ganguli in a devoted chapter in the same handbook [22]. The review referred to ceramics derived from pure and doped single oxides, pure and doped binary oxides, multicomponent oxides, and composites. 

Binary Selenides. Most binary selenides are formed by heating selenium in the presence of the element, reduction of selenites or selenates with carbon or hydrogen, and double decomposition of heavy-metal salts in aqueous solution or suspension with a soluble selenide salt, eg, Na2Se or (NH Se [66455-76-3]. Atmospheric oxygen oxidizes the selenides more rapidly than the corresponding sulfides and more slowly than the tellurides. Selenides of the alkali, alkaline-earth metals, and lanthanum elements are water soluble and readily hydrolyzed. Heavy-metal selenides are insoluble in water. Polyselenides form when selenium reacts with alkali metals dissolved in liquid ammonia. Metal (M) hydrogen selenides of the M HSe type are known. Some heavy-metal selenides show important and useful electric, photoelectric, photo-optical, and semiconductor properties. Ferroselenium and nickel selenide are made by sintering a mixture of selenium and metal powder. 

Refractory oxides are an important class of materials that enable processes to exploit extreme environments. A wide variety of unary, binary, and ternary oxides can be considered refractory, based on their melting temperatures. Refractory oxides are generally prepared from powdered precursors using standard ceramic forming techniques such as casting, pressing, or extrusion, and subsequently sintered to achieve final density. In addition to chemical compatibility, the physical properties of refractory oxides such as thermal expansion coefficient, thermal conductivity, modulus of elasticity, and heat capacity must be considered when selecting an oxide for a specific application. 

Aerogel powders of binary aluminate and zirconate oxides were prepared by a sol-gel technique and super-critical drying. The synthesis conditions are described and initial properties. Changes in the surface area and phases present in these powders and several reference materials are followed as they are heated at various temperatures in air cmtaining 10 vol.% water vapor. In addition, a time series was done on the most sintering resistant material (LaAli lOig) in ordtf to estimate its sintering rate. 

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