Thermodynamic analyses of structural phase transition of Pr 2NiO4+δ involving variation of oxygen content

Eiki Niwa, Kazuya Wakai, Tetsuya Hori, Keiji Yashiro, Junichiro Mizusaki, Takuya Hashimoto

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

Structural phase transition behavior of Pr2NiO 4+δ, which attracts interest as new cathode material for solid oxide fuel cells, was investigated by DSC and TG-DTA under controlled oxygen partial pressure, P(O2). It was revealed that the structural phase transition from orthorhombic phase to tetragonal phase involved discrete decrease of oxygen content in Pr2NiO4+δ and that the phase transition temperature, Tp, decreased with decreasing P(O 2). Variation of enthalpy, ΔH, and entropy, ΔS, at the phase transition per one molar Pr2NiO4+δ were calculated from the peak area of DSC and they were independent on P(O 2) between 1.0 × 10-1 bar and 2.25 × 10 -3 bar. From the linear relationships between Tp and RTpln P(O2) and between 1/Tp and Rln P(O 2), variation of standard enthalpy, ΔH, and standard entropy, ΔS, of the phase transition per one molar O2 were calculated, showing fair agreement with ΔH and ΔS. The variation of oxygen content at the phase transition, Δδ, increased with decreasing P(O2), which can be attributed to valence variation of Pr in tetragonal Pr2NiO4+δ by P(O2).

Original languageEnglish
Pages (from-to)129-134
Number of pages6
JournalThermochimica Acta
Volume575
DOIs
Publication statusPublished - 2014 Jan 1

Keywords

  • DSC
  • Ellingham diagram
  • PrNiO
  • Structural phase transition
  • TG

ASJC Scopus subject areas

  • Instrumentation
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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