Solid + Liquid Equilibria for the Systems CsBr + ErBr₃ + H₂O and CsBr + ErBr₃ + HBr (∼12.3%) + H₂O at 298.15 K and Atmospheric Pressure and Thermodynamic and Fluorescent Properties of the New Solid-Phase Compound

Abstract

The phase equilibria of the ternary system CsBr + ErBr 3 + H 2 O and the quaternary system CsBr + ErBr 3 + HBr (∼12.3 %) + H 2 O at 298.15 K were determined experimentally with the isothermal solubility method. Based on the measured solubility data, the corresponding phase diagrams were plotted. In the ternary system, three crystallization regions corresponding to CsBr, 3CsBr·2ErBr 3 ·16H 2 O, and ErBr 3 ·9H 2 O were found. Similarly, there were three crystallization regions corresponding to CsBr, 3CsBr·2ErBr 3 ·16H 2 O, and ErBr 3 · 7H 2 O in the quaternary system. The phase diagrams of the ternary and quaternary systems were compared, and it showed that (1) a new double salt 3CsBr·2ErBr 3 ·16H 2 O was formed which was incongruently soluble in the two systems; (2) the area of the crystallization region of 3CsBr·2ErBr 3 ·16H 2 O increased with the increasing concentration of HBr in the equilibrium liquid phase, and (3) ErBr 3 ·9H 2 O transformed into ErBr 3 ·7H 2 O when the HBr reached a certain amount. The new solid-phase compound 3CsBr·2ErBr 3 ·16H 2 O was characterized by chemical analysis, XRD, and TG-DTG techniques. The standard molar enthalpy of solution of 3CsBr·2ErBr 3 ·16H 2 O in water was confirmed to be −(6.69 ± 0.29) kJ·mol −1 by microcalorimetry in the limit of infinite dilution and its standard molar enthalpy of formation was determined to be −(7846.1 ± 1.2) kJ·mol −1 . The fluorescence excitation and emission spectra of 3CsBr·2ErBr 3 ·16H 2 O were measured. The results indicated that up-conversion spectra of the new solid phase compound exhibit at 470 nm and are excited at 710 nm.

(Solid + Liquid) Phase Equilibria for the Systems CsBr + EuBr3 + H2O and CsBr + EuBr3 + HBr (∼12.3%) + H2O at 298.15 K and Atmospheric Pressure and Thermodynamic and Fluorescent Properties of the New Solid-Phase Compound

“…Moreover, the phase chemical reactions of the present quaternary system are similar to those of the CsBr + REBr 3 + HBr (∼13%) + H 2 O (RE = La, Ce, Pr, Nd, and Sm) quaternary systems. − The compounds 5CsBr·2REBr· n H 2 O (5:2 type) were formed in CsBr + REBr 3 + HBr (∼13%) + H 2 O (RE = La, Ce, Pr, Nd, Sm, and Eu) systems. But the phase chemical behaviors of the present quaternary system are different from those of the CsBr + REBr 3 + HBr (∼13%) + H 2 O (RE = Dy, Er, and Tm) quaternary systems. − 5CsBr·3DyBr·24H 2 O (5:3 type) was verified in the CsBr + DyBr 3 + HBr (∼13%) + H 2 O system; however, the 3:2 type compound 3CsBr·2REBr 3 ·16H 2 O was obtained in the systems CsBr + REBr 3 + HBr (∼12.3%) + H 2 O (RE = Er, Tm).…”

“…From the comparison of the present ternary system with the reported ternary systems, ,,, the phase chemical reactions of the five systems CsBr + REBr 3 + H 2 O (RE = La, Ce, Pr, Nd, and Sm) are similar in that they all have compounds 2CsBr·REBr 3 ·10H 2 O (2:1 type). The compounds 3CsBr·2REBr 3 ·16H 2 O (3:2 type) were formed in CsBr + REBr 3 + H 2 O (RE = Er and Tm) systems, so the phase chemical reactions of the two systems are analogous.…”

“…29 The literature data seem to be distinctly overestimated. 23,30 From the comparison of the present ternary system with the reported ternary systems, 13,14,21,22 3 shows the solubility for the quaternary system of CsBr + EuBr 3 + HBr (∼12.3%) + H 2 O and the central projection data on the trigonal basal face for the CsBr + EuBr 3 + H 2 O system at 298.15 K. The ion concentration of equilibrium liquid phase and the wet residue are shown as mass percent. Figure 2 displays the corresponding phase diagram.…”

“…Some potential upconversion materials, such as Er 3+ -doped RbGd 2 C1 7 and RbGd 2 Br 7 ; Cs 3 Yb 2 Cl 9 and Cs 3 Yb 2 Br 9 ; Cs 3 Y 2 Br 9 (10% Dy 3+ and Cs 3 Dy 2 Br 9 ); Cs 3 Er 2 X 9 (X = Cl, Br, I); and Er 3+ in Cs 3 Lu 2 Br 9 , were synthesized by means of the Bridgman technique − or improved Meyer method . In order to prepare the alkali metal bromide/rare-earth metal bromide compounds by phase equilibrium method and acquire the solubility of cesium bromide and rare-earth bromide at 298.15 K in H 2 O or HBr (∼12 mass %)–H 2 O medium, the phase equilibria for CsBr + REBr 3 + H 2 O (RE = La, Ce, Pr, Nd, Sm, Er, and Tm) ternary systems and CsBr + REBr 3 + HBr (∼13%) + H 2 O (RE = La, Ce, Pr, Nd, Sm, Dy, Er, and Tm) quaternary systems were reported continuously, − and the related research on rare-earth halide in aqueous media was compiled exhaustively . These phase diagrams were highly valuable for researchers to learn the phase equilibrium relationship of CsBr and REBr 3 in aqueous systems.…”

Phase Equilibria in the CsBr–TbBr3–H2O and CsBr–TbBr3–HBr (∼13.0 wt %)–H2O Systems at 298.1 K and the Standard Molar Enthalpy of Formation for Cs3TbBr6·10H2O

“…Meanwhile, the thermodynamic properties of some compounds were investigated. The water–salt systems cesium bromide + rare earth bromide + water (rare earth = lanthanum, cerium, praseodymium, neodymium, samarium, europium, holmium, erbium, thulium) and cesium bromide + rare earth bromide + hydrobromic acid (∼12.0 mass %) + water (rare earth = lanthanum, cerium, praseodymium, neodymium, samarium, europium, dysprosium, holmium, erbium, thulium) have been determined in our previous reports and in the Wang et al laboratory. − Moreover, some of the quaternary systems have been evaluated . The research results showed that the new solid-phase compound existed in corresponding ternary and quaternary systems.…”