Reaction Kinetics in the Ca-Mn-O System

Abstract

Mixed metal oxides represent a large class of inorganic materials which possess many important properties not found in the more limited binary oxides. Mixed metal oxides can stabilize high oxidation states of transition elements, have extensive ranges of either anion or cation nonstoichiometry and provide new structural arrangements not possible in a simple oxide. This very flexible class of compounds, however, is limited in applications because of the difficulties involved in the preparation of high surface area materials. The usual routes to these compounds generally involve reaction at high temperature for long periods of time. These conditions are required to overcome the slow reaction kinetics that occur when two solids are brought together. Of course these same conditions of high temperature and long times lead to crystallite growth and low surface areas. In addition, the high temperatures prevent the formation of compounds containing high valent cations such as Mn⁴⁺.