Defect Structure, Transport Properties, and Chemical Expansion in Ba0.95La0.05FeO3-delta

Abstract

This work systematically investigates the oxygen nonstoichiometry, defect structure and mass/charge transport properties of Ba0.95La0.05FeO3-delta (BLF). Thermogravimetric measurement and coulometric titration were performed to determine change in oxygen nonstoichiometry (delta) with oxygen partial pressure (P-O2) in 10(-17) <= (P-O2/atm) <= 0.21 and 850 <= (T/degrees C)<= 900 range. The delta-P-O2-T plot showed "S-type" shape with a crossover plateau around delta approximate to 0.475. Defect modelling was used to explain the nonstoichiometry data and partial molar thermodynamic quantities for oxygen were determined. The DC 4-probe conductivity measurement was performed which showed a typical semiconductor-to-metal transition with temperature around the conductivity maxima at 450 degrees C. Electrical conductivity relaxation (ECR) measurement was performed to extract partial ionic conductivity, chemical diffusivity and surface exchange kinetics of oxygen ion by using Nernst-Einstein equation and Fick&apos;s law. Isothermal chemical expansion was measured by dilatometry measurement in the range of 10(-2) <= (P-O2/atm) <= 0.21 and 850 <= (T/degrees C) <= 950. (c) 2021 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.