- The High-temperature Gas-balance (HTGB[1]) has been established as a new method for investigations of heterogeneous phase equilibria with volatile components [1,2]. This equipment is notably well suited to analyze reversible heterogeneous equilibria which occur during chemical vapor transport reactions (CVT[3]).
Experimental proof has been furnished by vapor transports of germanium and germanium(II) telluride using iodine as a transport addition. Initially the sublimation of iodine has been observed (section a – Fig. 1). The formation of GeI4(g) as the actual transport agent follows (b). Finally, the transport reaction occurs under reversible formation GeI2(g) (c).