The Responsibility of High Temperature Scientists

When I was first introduced to high temperature research on joining the Manhattan Project in January 1943, I was surprised by the novelty and unexpected complexity of high temperature systems. At room temperature, one expects a mixture of aluminum metal with an aluminum halide or aluminum oxide to be restricted to the zero and 3+ oxidation states. The predictions of chemical behavior upon heating, based on room temperature behavior, are grossly in error because of neglect of the additional oxidation states that become increasingly important as the temperature is increased. In high temperature aluminum—oxygen systems, for example, the trivalent gaseous species has not even been reported, but Al₂O, AlO, Al₂O₂, and AlO₂ gases have been established. For gaseous systems in equilibrium with condensed phases, one can demonstrate that the gaseous phase will become more and more complicated as the temperature is increased both with respect to the number of species and with respect to the complexity of the molecules.