ECI Digital Archives

Title

Oxygen nonstoichiometry and thermodynamic quantities of Perovskite-Type La1- xSrxFeO3-δ(x=0.2, 0.5, 0.8)

Authors

Hohan Bae, Chonnam National University, South KoreaFollow
Jaewoon Hong, School of Materials Science and Engineering, Chonnam National University
Sun-Ju Song, School of Materials Science and Engineering, Chonnam National University
Mathur Lakshya, School of Materials Science and Engineering, Chonnam National University

Conference Dates

March 10-14, 2019

Abstract

In this work, the defect structure analysis of La_1-xSr_xFeO_3-δ (x=0.2, 0.5, 0.8) was presented. Thermogravimetric measurements were performed to determine the change in oxygen nonstoichiometry (Δδ) with oxygen partial pressure (pO₂) in 10^-19 ≤ (pO₂/atm) ≤ 0.21 and temperature in 750 ≤ (T/℃) ≤ 900 range. La_1-xSr_xFeO_3-δ showed a clear electronic stoichiometric point around δ»3-x/2. The relative partial molar enthalpy (h_o-h_o^o) and entropy (s_o-s_o^o) of oxygen were calculated from δ-pO₂-T relation by using Gibbs-Helmholtz equation. The negative sign of h_o-h_o^o and s_o-s_o^o indicated that the incorporation of oxygen was an exothermic process and showed that the experimentally observed variations in h_o-h_o^o and s_o-s_o^o with δ matched well with the statistical thermodynamic model proposed by Mizusaki^[1]. The defect diagram analysis showed that in n-type regime Fe²⁺ concentration varied with (pO₂)^-1/4 whereas in p-type regime Fe⁴⁺ concentration varied with (pO₂)^1/4.

Reference

[1] J. Mizusaki et al. J. Solid State Chem. 67 (1987) 1-8.

Recommended Citation

Hohan Bae, Jaewoon Hong, Sun-Ju Song, and Mathur Lakshya, "Oxygen nonstoichiometry and thermodynamic quantities of Perovskite-Type La1- xSrxFeO3-δ(x=0.2, 0.5, 0.8)" in "Nonstoichiometric Compounds VII", ECI Symposium Series, (2019). https://dc.engconfintl.org/nonstoichiometric_vii/11