2. Historical background
Aim: To give an overview of the historical development of studies of high temperature chemical and physical behaviour of inorganic materials.
Topic description and teaching suggestions: This historical introduction should draw the route from the pioneeristic studies on the high temperature behaviour of inorganic materials to the recognition of the importance of high temperature chemistry as a new area of research concerning properties, reactivity and developments of new advanced materials for applications in extreme environments. The various definitions of high temperature chemistry and high temperature reactions given by the founders of this discipline can be fruitfully discussed. As discussed in some of the references given below, the term “high temperature chemistry” is best defined in terms of characteristic chemical reactions rather than in terms of temperature ranges. Indeed it is not possible to give a definite lower value above which temperatures may be termed “high”. Since the early stages of this area of research, studies were focused particularly on the condensed phase-gas phase processes carried out under high temperature-low pressure conditions and on the characterization of high temperature vapours and new molecules of unexpected complexity. In fact, vaporization processes become increasingly important at high temperatures, gaseous species with unfamiliar oxidation states of the elements often form and their complexity may increase with temperature. In this context most of the studies carried out so far over the decades have been performed from 500 up to 3000 K with a large majority in the range 1200-2500 K. Also, solid phases with stoichiometries different from those usual at room temperature may be stable at high temperature.
W. Hastie, "High Temperature Vapors. Science and Technology", Academic Press, New York, 1975
L. Margrave, editor, "The Characterization of High Temperature Vapors" Wiley & Sons, New