ABSTRACT
The word spinel is derived from the Italian word spinella, a diminutive of spine or thorn (from its sharply pointed crystals). Since the determination of the crystal structure of the mineral spinel, MgAl2O4, by Bragg in 1915 [1], several metal oxides and mixed metal oxides have been found to possess the same structure. There are at least 30 oxide minerals included in spinel supergroup. Such materials, especially those containing iron (ferrites), belong to the group of strategic materials, which are used in a wide area of modern technologies. They exhibit suitable combined electrical and magnetic properties and therefore soon became extremely important for many technological applications, such as high-frequency devices, memory cores, and magnetic recording.
