The ever-increasing importance of chemical reactions at high and superhigh temperatures in crystalline, amorphous, and semicrystalline SOlids, as well as the reactions of these solids with gases, prompted the authors of this book to examine critically the literature available in this field and to present a general review of the subject. In this monograph we discuss those chemical and physicochemical points which we consider to be most important for solving a series of problems in the preparation and use of new inorganic materials. We hope that this book will be of interest to the many specialists working on inorganic materials. N. A. Toropov PREFACE Modem technology demands ever more materials with high mechanical strength, heat and chemical re­ sistance, fire resistance, special electrical properties, particular behavior toward active radiations, etc. The search for such materials requires the study of various chemical compounds, metallic alloys, and other fused in­ organic systems, especially oxide systems. Materials based on oxides begin to assume increasing importance in many fields of the new technology. In this connection the investigation of oxides and systems consisting of two and more oxides is expanding greatly.