Zum System Bi₂O₃ /Bi₂Se₃/BiCl₃,I. Das Zustandsdiagramm Bi₂O₃/Bi₂Se₃/BiCl₃/On the System Bi₂O₃/Bi₂Se₃/BiCl₃, I. The Phase Diagram Bi₂O₃/Bi₂Se₃/BiCl₃

Abstract

Abstract The phase relations in the quaternary system Bi/Se/O/Cl have been studied and the existence of several new compounds in the pseudotemary area Bi 2 O 3 /Bi 2 Se 3 /BiCl 3 has been established by solid state and chemical vapour transport reactions. The phase diagram is derived from X-ray powder diffraction and thermal analysisdata, and from measurements of the decomposition pressure behaviour. Three new quaternary phases with different compositions exist in the system: Bi 4 O 4 SeCl 2 , Bi 10 O 12 SeCl 4 and Bi 22 O 28 SeCl 8 . By estimation of the thermodynamic data of the quaternary phases it is possible to calculate complex heterogeneous chemical equilibria between all the binary, ternary and quaternary compounds of the phase diagram. As a result, we can describe thermodynamically the observed phase relations and the direction of thermal decomposition of the respective compounds.