Energetics of Rare Earth Manganese Perovskites A1-xA′xMnO3 (A=La, Nd, Y and A′=Sr, La) Systems

Christel Laberty, Alexandra Navrotsky, C. N.R. Rao, Pierre Alphonse

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43 Scopus citations

Abstract

High temperature reaction calorimetry using molten lead borate as solvent has been used to study the thermochemistry of NdMnO3, YMnO3, La1-xSrxMnO3 (with 0<x<0.5), and Ln0.5Ca0.5MnO3 (with Ln=La, Nd, Y). The enthalpies of formation of these multicomponent oxides from their binary constituents have been calculated from the measured enthalpy of drop solution. The energetic stability of the perovskite depends on the size of the A cation. The enthalpy of formation of YMnO3 (smallest A cation) is more endothermic than those of NdMnO3 and LaMnO3. The energetics of the perovskite also depends on the oxidation state of the B site's ions. In the La1-xSrxMnO3 system, the energetic stability of the structure increases with the Mn4+/Mn3+ ratio. The new values of the enthalpies of oxidations, with reliable standard entropies, were used to plot the phase stability diagram of the lanthanum-manganese-oxygen system in the temperature range 300-1100 K. The LaMnO3/MnO phase boundary evaluated in this study agrees with the one published by Atsumi et al. calculated from thermogravimetric and conductivity measurements.

Original languageEnglish (US)
Pages (from-to)77-87
Number of pages11
JournalJournal of Solid State Chemistry
Volume145
Issue number1
DOIs
StatePublished - Jun 1999
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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