Untersuchungen zum System SmOBr/SeO2

Investigation on the System SmOBr/SeO₂ The existence of three ternary phases SmSeO₃Br, SmSe₂O₅Br and SmSe₃O₇Br on the line SmOBr—SeO₂ in thermodynamically equilibrium has been established for the first time. The phases were synthesized by solid state reaction and characterized by X‐ray and IR‐spectroscopy. The phase barogram and phase diagram were determined by DTA and total pressure measurements. The enthalpies of formation and the standard entropies of the phases were calculated from the vapour pressure data. In addition, the enthalpies of formation were followed from solution calorimetry of the phases and SmOBr and SeO₂, respectively. SmSe₃O₇Br and SmSe₂O₅Br melts peritectically at 350 °C and 600 °C correspondently. SmSeO₃Br shows two diffusion phase transitions in solid state: 160 °C (g‐b) and 375 °C (b‐a).