Metal-Rich Metal-Metalloid Phases,

This is a review of borides, carbids, nitrides, and oxides of transition elements, often in combination with non-transitional elements. In the metal rich compounds the metalloid atom is isolated and surrounded by six or eight transition metal atoms in close contact with each other. The metalloid atom is therefore interstitial, sometimes in the strict sense that the phase fields include metalloid-free unfilled compositions. Five structure types are singled out because they occur extensively and because the author is familiar with them through his own work. There may be some initial objection to having borides, carbides, nitrides, and oxides lumped together in one class. It is indeed rare, but the entire range from borides to oxides. On the other hand, there is so much overlap between types that a common classification does seem justified.