Thermochemische Untersuchungen am System Bi/Se/O III. Zum quasibinaren System Bi_2O_3-Bi_2Se_3 und zum ternaren Bereich Bi_2O_3-Bi_2O_2Se-Se-SeO_2

摘要

Only the ternary phase Bi_2O_3Se is shown to exists in the thermodynamical equilibrium in the investigated ternary system on the binary line Bi_2O_3-Bi_2Se_3. Its thermal decomposition was measured in a quartz membrane zero manometer. The enthalpy of formation and the standard entropy were derived from the temperature function of the decomposition equilibrium: #DELTA#H_f deg (Bi_2O_3Se_(s, 298)) = -104,6 +- 4,0 kcal/mol S deg(Bi_2O_3Se_(s, 298)) = 43 +- 3 cal/K centre dot mol. The coexistence ranges in the ternary region Bi_2O_3-SeO_2-Bi_2Se-Se were followed by X-ray diffraction, IR spectroscopy and total pressure measurements of binary and ternary compositions.