Thermodynamics Research Center / ThermoML | Thermochimica Acta

Above room temperature heat capacity and phase transition of lithium tetrahydroborate

El Kharbachi, A.[Abdelouahab], Nuta, I.[Ioana], Hodaj, F.[Fiqiri], Baricco, M.[Marcello]
Thermochim. Acta 2011, 520, 1-2, 75-9
ABSTRACT
New calorimetric determinations of molar heat capacity Cp,m of lithium tetrahydroborate (LiBH4) were performed in order to analyze the origin of the previously observed "anomaly" before the allotropic transition at 386 K. The above room temperature dependence of LiBH4 Cp,m was measured until approaching the melting point of the compound at 553 K and the abnormal behaviour was attributed to another phenomenon independent of the main crystalline phase transition. As a result, lower entropy of the transition AtrsS = 13.11 +- 0.23 J*K-1*mol-1 than that proposed in literature was obtained, which is in agreement with the observed anisotropy and crystal density decrease before the transition issued from recent X-ray diffraction indexing. An estimate of the liquid Cp,m of LiBH4 "molten salt" is proposed.
Compounds
# Formula Name
1 BH4Li lithium tetrahydroborate
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal 1
  • Crystal 1
  • Liquid
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Triple point temperature, K ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • DTA
  • 1
  • POMD
  • 1
  • Triple point temperature, K ; Crystal 1
  • Crystal 1
  • Liquid
  • Air at 1 atmosphere
  • DTA
  • 1
  • POMD
  • 1
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • Small sample (50 mg) DSC
  • 9
  • POMD
  • 1
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 1
  • Temperature, K; Crystal 1
  • Pressure, kPa; Crystal 1
  • Crystal 1
  • Small sample (50 mg) DSC
  • 12