Role of intermediate solid phase in the process of magnesium and lanthanum aluminates formation in sub- and supercritical water

Torbin, S.N.; Danchevskaya, M.N.; Martynova, L.F.; Muravieva, G.P.

Авторы: Torbin S.N., Danchevskaya M.N., Martynova L.F., Muravieva G.P.
Журнал: High Pressure Research
Том: 20
Номер: 1-6
Год издания: 2001
Издательство: Taylor & Francis
Местоположение издательства: United Kingdom
Первая страница: 109
Последняя страница: 119
DOI: 10.1080/08957950108206158
Аннотация: The synthesis of inorganic complicated powder oxides is of significant interest owing to wide application of these materials in modern engineering. In this paper the mechanism of fine crystalline magnesium and lanthanum aluminates formation in sub- and supercritical water was investigated. Mechanical mixtures of aluminium. hydroxide and magnesia as well as lanthana were used as precursors. The synthesis was carried out in water steam atmosphere at P approximate to 20 MPa and temperature of 300-400degreesC in the presence of small amounts of Cr(VI) ions. It was found, that the mechanism of this process cannot e represented in the frameworks of the traditional approach: dissolution of precursors in supercritical fluid and precipitation of the products. This approach assumes a complete homogenisation of reacting system at the intermediate stage of the process. By means of X-ray analysis of products of the intermediate stage of synthesis, the presence of a crystalline phase was revealed by us. This phase will be derived in an outcome dehydration of precursors, which are flowing past in quasi equilibrium conditions. In the case of MgAl2O4 the intermediate phase is boehmite, and in the case of LaAlO3 - lanthanum hydroxide. The structure and properties of these phases exert a decisive influence on the synthesis process and characteristics of formed product.
Добавил в систему: Муравьева Галина Петровна

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Role of intermediate solid phase in the process of magnesium and lanthanum aluminates formation in sub- and supercritical waterстатья

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