Energetics of magnesium, strontium, and barium doped lanthanum gallate perovskites

Jihong Cheng, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

LaGaO3 perovskites doped with Sr or Ba at the La site and Mg at the Ga site were prepared by solid-state reaction or sol-gel method and characterized. Enthalpies of formation from constituent oxides at 298K were determined by high-temperature oxide melt solution calorimetry. Energetic trends are discussed in terms of defect chemistry. As oxygen deficiency increases, formation enthalpies define three trends, LaGa1-yMg yO3-δ (LGM), La1-xSrxGa 1-yMgyO3-δ (LSGM), and La 1-xBaxGa1-yMgyO3-δ (LBGM). They become less exothermic with increasing doping, suggesting a dominant destabilization effect from oxygen vacancies. The endothermic enthalpy of vacancy formation is 275±37, 166±18 and 138±12kJ/mol of VO.. for LGM, LBGM and LSGM, respectively. Tolerance factor and ion size mismatch also affect enthalpies. In terms of energetics, Sr is the best dopant for the La site and Mg for the Ga site, supporting earlier studies, including oxygen ion conductivity and computer modeling.

Original languageEnglish (US)
Pages (from-to)126-133
Number of pages8
JournalJournal of Solid State Chemistry
Volume177
Issue number1
DOIs
StatePublished - Jan 2004
Externally publishedYes

Keywords

  • Doped lanthanum gallate
  • Enthalpy of formation
  • Oxygen vacancies
  • Perovskites
  • Solid electrolyte
  • Solid oxide fuel cells
  • Thermodynamics
  • Tolerance factor

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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