Crystal Growth Via the Gas Phase by Chemical Vapor Transport Reactions

Abstract By means of chemical vapor transport reactions ( CVT ) a variety of solid‐state compounds can be prepared, mostly as impurity free single crystals. Representatives are well‐established for elements, intermetallics, halides, oxides, sulphides, selenides, tellurides, pnictides, and so on. The fundamental thermodynamic principles of CVT reactions are discussed for both single equilibrium reactions (Schaefer model) and more complex reaction mechanisms using the term “gas phase solubility.” Different working techniques for realization of vapor transport experiments are described in detail: application of suitable ampoule materials, furnace assembly, handling of different transport agents, calculation of vapor pressure, experimental procedure. The characteristic vapor transport behavior is described for selected representatives of above‐mentioned classes of solids. Accordingly, some information is given concerning the choice of appropriate transport agent, the evaluation of transport direction, and the viable transport conditions. The simplified deduction or estimation of transport conditions for new compounds of related chemical composition or similar chemical behavior is discussed for the different substance classes. At least, complex thermodynamic modeling of CVT reactions applying the CalPhaD method using freeware is introduced.