Enthalpies of phase transition in the lanthanide chlorides LaCl3, CeCl3, PrCl3, NdCl3, GdCl3, DyCl3, ErCl3 and TmCl3

Zeitschrift Für Naturforschung A

Ingier-Stocka

Gadžurić

et al. 2007

This paper continues our research program on lanthanide halide-alkali metal halide systems. Differential scanning calorimetry (DSC) was used to investigate the phase equilibria of the CeBr 3 -KBr system. This system is characterized by the two congruently melting compounds K 3 CeBr 6 and K 2 CeBr 5 and the three eutectics located at the CeBr 3 mole fractions 0.193 (837 K), 0.295 (855 K) and 0.555 (766 K). K 3 CeBr 6 forms at 775 K and melts congruently at 879 K with the related enthalpies 54.5 and 41.7 kJ mol −1 , respectively. K 2 CeBr 5 melts congruently at 874 K with the enthalpy 82.4 kJ mol −1 . The electrical conductivity was measured of all CeBr 3 -KBr mixtures and of the pure components down to temperatures below solidification. The experimental determinations were conducted over the entire composition range in steps of about 10 mol%. The specific electrical conductivity decrease with increasing CeBr 3 concentration, with significantly larger conductivity changes in the potassium bromide-rich region. The results are discussed in terms of possible complex formation.

Section: Measurementsmentioning

confidence: 99%

Phase Diagram and Electrical Conductivity of CeBr₃-KBr

Zeitschrift Für Naturforschung A

Ingier-Stocka

Gadžurić

et al. 2007

“…However, fusion temperatures determined from cooling curves were lower by 15 K than those obtained from heating curves. This supercooling phenomenon is common for almost all lanthanide halides [1,3,4]. Due to supercooling, the temperature and fusion enthalpy of LaBr 3 were determined from heating DSC curves.…”

Section: Resultsmentioning

confidence: 99%

Heat Capacity and Thermodynamic Properties of LaBr₃ at 300 – 1100 K

Zeitschrift Für Naturforschung A

Ingier-Stocka

Ziolek

et al. 2004

Self Cite

The heat capacity of solid and liquid LaBr 3 was measured by Differential Scanning Calorimetry (DSC) in the temperature range 300 -1100 K. The obtained results were fitted by a polynomial temperature dependence. The enthalpy of fusion of LaBr 3 was also measured. By combination of these results with the literature data on the entropy, S 0 m (LaBr 3 , s, 298.15 K) and the standard molar enthalpy of formation, ∆ form H 0 m (LaBr 3 , s, 298.15 K), the thermodynamic functions of lanthanum tribromide were calculated up to 1300 K.

“…According to them, the systems with lithium chloride are simple eutectic systems (LaCl 3 , CeCl 3 , PrCl 3 and NdCl 3 ), systems with LiLn 2 Cl 7 compounds that decompose to a solid-state phase (Ln = Sm, Tb) or systems with Li 3 LnCl 6 compounds that melt incongruently (Ln = Dy, Ho, Er, Yb). According to the literature data [16], the DyCl 3 -LiCl system is characterized by the existence of Li 3 DyCl 6 compound that undergoes a solid-solid phase transition at 743 K and melts incongruently at 748 K. It should be pointed out that the authors did not inform about a solid-solid phase transition of DyCl 3 , which is well known from the literature [17]. So, we decided to reinvestigate this system by DSC.…”

Section: Introductionmentioning

confidence: 97%

Reinvestigation of the DyCl3–LiCl binary system phase diagram

Dańczak

2016

J Therm Anal Calorim

Self Cite

The phase equilibria in the DyCl 3 -LiCl binary system were established on the basis of differential scanning calorimetry (DSC) measurements. One compound, namely Li 3 DyCl 6 , is formed in this system. It melts congruently at 768 K with enthalpy of 51.6 kJ mol -1 . DSC curves for eutectic composition and for compositions close to eutectic (on the left and right side of eutectic) are identical. Small effect related to the liquidus is shadowed by a big effect related to eutectic, and only one thermal effect is visible. This is the reason that eutectic composition can not be determined directly. The only possibility to determine it precisely is a creation of Tammann diagram. Two eutectics, namely LiCl-Li 3 DyCl 6 and Li 3 DyCl 6 -DyCl 3 , located at DyCl 3 mol fractions x = 0.206 (T = 746 K) and x = 0.542 (T = 674 K) were found from Tammann's plots, which predict, through application of the lever rule, the variation of the enthalpy associated with eutectic melting as a function of composition.