Chemistry of Vaporization of Refractory Materials

Most recently the practical importance of high temperature vaporization reactions has appeared in the synthesis of pure materials through vapor transport reactions and in the study of the movement of materials in nuclear power reactor experiments. The most recent basic development is the establishment, at temperature, of the range of nonstoichiometry in oxides. Long‐standing applications of vaporization studies are in the measurement of thermodynamic properties and the discovery of new species. A discussion is given of the principles of physical chemistry important in vaporization studies, notably the concepts of equilibrium, phase behavior, thermodynamics, solid solution, and kinetics. The important factors influencing equilibrium vaporization phenomena are discussed and illustrated. A proper course of a vaporization study consisting of 9 stages is proposed. The important experimental techniques of Knudsen effusion, Langmuir vaporization and mass spectrometry are discussed. The principles, the factors, the course of a study and the experimental techniques and procedures are illustrated by recent work on the Ti‐O system.