Low-temperature thermodynamic properties of dimeric tris(2,2,6,6-tetramethyl-3,5-heptanedionato) europium

M. A. Bespyatov, I. S. Cherniaikin, P. A. Stabnikov, A. R. Tsygankova, T. M. Kuzin, N. V. Gelfond

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2 Citations (Scopus)

Abstract

A sample of dimeric tris(2,2,6,6-tetramethyl-3,5-heptanedionato) europium ([Eu(C11H19O2)3]2 or dipivaloylmethanate europium) was synthesized. Chemical analysis, elemental analysis and X-ray crystallography were used to characterize composition and structure of the complex. Low-temperature heat capacity of the sample was measured by adiabatic method in a temperature range from 8.63 K to 312.90 K. The Debye temperature at 0 K was calculated. Thermodynamic functions (entropy, enthalpy, reduced Gibbs energy) in a range (0–312) K have been calculated using the obtained experimental heat capacity data. An anomaly in the functional behaviour of heat capacity was detected in a temperature range from 250 K to 270 K, with a maximum at Tc = (262.36 ± 0.01) K. A reversible colour change (thermochromism) of europium dipivaloylmethanate crystals upon cooling below 245 K was detected. Anomalous contributions to entropy and enthalpy have been revealed. The nature of the effects detected is discussed.

Original languageEnglish
Article number105904
Number of pages6
JournalJournal of Chemical Thermodynamics
Volume140
DOIs
Publication statusPublished - 1 Jan 2020

Keywords

  • Adiabatic calorimetry
  • Europium (III) beta-diketonates
  • Low-temperature heat capacity
  • Thermochromism
  • Thermodynamic functions
  • TRANSITION
  • VIBRATION-SPECTRA
  • HEAT-CAPACITY
  • DEPENDENCE

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