Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

In this study, the (solid + liquid) phase equilibria for the two systems of CsBr + EuBr3 + H2O and CsBr + EuBr3 + HBr (~12.3%) + H2O at 298.15 K and atmospheric pressure were determined by isothermal solubility method. Schreinemaker wet residue approach was used to determin the solid phases obtained from the studied systems. The related phase diagrams were depicted based upon the experimental data. There were two invariant points, three invariant curves, and three crystallization fields corresponding to CsBr, 5CsBr*2EuBr3*20H2O, and EuBr3*6H2O in the two phase diagrams. New double salt 5CsBr*2EuBr3*20H2O was incongruently soluble in the two systems. The content of EuBr3 in two invariant points decreased as the concentration of HBr in equilibrium liquid phase increased, while that of CsBr changed a little. The new solid-phase compound 5CsBr*2EuBr3*20H2O was investigated using chemical, XRD, and TG-DTG analyses. Additionally, the standard molar enthalpy of solution for 5CsBr*2EuBr3*20H2O in water was confirmed to be 104.69 +- 0.88 kJ/mol by microcalorimetry; its standard molar enthalpy of formation was determined as being -(9659.7 +- 1.6) kJ/mol. The fluorescence excitation and emission spectra of 5CsBr*2EuBr3*20H2O were acquired. The results indicate that upconversion spectra of 5CsBr*2EuBr3*20H2O exhibited pure green upconversion luminescence under 785 nm excitation.