Characterization of (La0.9Sr0.1)0.95Cr0.85Mg0.10Ni0.05O3−δ Ceramics for Perovskite Related Membrane Reactor

Abstract

(La0.9Sr0.1)0.95Cr0.85Mg0.10Ni0.05O3 (LSCMN) ceramics sintered at temperatures 1100–1700°C in air were characterized using powder x-ray diffraction, field emission scanning electron microscopy coupled with energy dispersive x-ray spectroscopy, transmission electron microscopy, differential scanning calorimetry, and inductively-coupled plasma spectroscopic analysis. Pervoskite ceramics with the highest density (porosity between 2–5%) were sintered at 1650°C for 24 hours. Secondary phases at a level of 3–5% porousity have been detected in the LSCMN initial powder received and sintered samples. LSCMN initial powder and ceramics exist in orthorhombic phase at room temperature and exhibits a first order phase transition into rhombohedral phase in the temperature range 70–95°C. Temperature of phase transition depends on grain size. Hardness and fracture toughness of LSCMN were studied by nanoindentation and microindentation methods. At low indentation depths hardness values depend significantly on the number of grains effected by the indent and crack formation. Indentation size effect was quantified in terms of Nix-Feng and power-low models. At high loads the apparent hardness is almost two times less than hardness of LSCMN monocrystalls.

PEROVSKITE-LIKE (La0.75Ca0.25)0.95Cr1-xFexO3-δ AS POTENTIAL ELECTRODE MATERIALS FOR SYMMETRIC SOLID OXIDE FUEL CELLS

“…2) which is reproducible upon heating and cooling observableboth in air and argon atmospheres. In accordance with literature data [4,[26][27][28][29][30], this behavior might be associated with reversible 1 st order transition of the orthorhombic structure into the rhombohedral one. For the title materials, this effect occurs at significantly higher temperatures as compared to some other chromitesshown in Table 2 which might originate from an increase of transition temperatures upon Ca-or Fe-doping; the effect of Fe introduction on the transition temperature confirms this suggestion.…”