ABSTRACT
The core of the earth is composed of a mass of metals (˜90% iron, 9% nickel, and 1% other metals), while the earth’s crust—the outer shell extending to a depth of about 13 km—is dominated by oxygen (47%) [1]. Not surprisingly, metal oxides constitute the most abundant and most accessible of inorganic materials in nature [1,2]. The fact that the periodic table is dominated by metals means, further, that a wide variety of metal oxides can be formed, spanning a broad range of physical and chemical properties. These properties provide the basis for the many scientific and technological applications of metal oxides, some selected examples of which are collected in Table 1 [3].
