Thermodynamics of the thermal decomposition and formation of ytterbium (III) oxide selenide

Article abstract of DOI:10.1016/0022-5088(91)90263-4

The thermal decomposition of (YbO)₂Se(s) was studied over the temperature range 1753-1997 K by the Knudsen effusion weight loss technique. It was found that the decomposition leads to a gas phase containing ytterbium and selenium with a molar ratio of 2:3 and to a residue of Yb₂O₃(s). Using literature and estimated enthalpy and entropy data for the gaseous species Yb, Se, YbSe and Se₂, the principal decomposition reaction was established from the rates of effusion, and the second-law and third-law enthalpies and entropies were found for this reaction. A value of -1594±33 kJ mol^-l is derived for the standard enthalpy of formation of (YbO)₂Se(s). The feasibility of this value is discussed in view of the significant decrease in the formula volume accompanying the formation of (YbO)₂Se from Yb₂O₃ and Yb₂Se₃.