Structural study of a sol&#x2013;gel derived novel solid oxide fuel cell perovskite: (La_{1&#x2212;<i>x</i>}Sr_<i>x</i>)(Cr_0.85Fe_0.05Co_0.05Ni_0.05)O_3&#x2212;δ

다국어 초록 (Multilingual Abstract)

<P>The effect of composition on the structure of the new solid oxide fuel cell (SOFC) perovskite (La<SUB>1−<I>x</I></SUB>Sr<SUB><I>x</I></SUB>)(Cr<SUB>0.85</SUB>Fe<SUB>0.05</SUB>Co<SUB>0.05</SUB>Ni<SUB>0.05</SUB>)O<SUB>3−δ</SUB> is studied using x-ray diffractometry, pycnometry, and Fourier-transform infrared and Raman spectroscopy. Samples were synthesized using the Pechini method via doping the La site with Sr<SUP>2+</SUP>, to a composition with <I>x</I> = 0–0.4 mole fraction, and at the Cr site with 0.05 mol of Co<SUP>2+</SUP>,Fe<SUP>2+</SUP> and Ni<SUP>2+</SUP>, and the structural results were compared with those for orthorhombic LaCrO<SUB>3</SUB>. The samples were orthorhombic perovskite of the <I>Pnma</I> space group. A second phase, monoclinic SrCrO<SUB>4</SUB>, was also observed, whose content increased linearly with increasing <I>x</I>. A large decrease in the lattice and hence volume was observed for the sample with <I>x</I> = 0.1, which was accompanied by a sharp decrease in the Cr−O bond length, tilt angle and crystallite size. The structural parameters were almost invariant for <I>x</I> = 0.1–0.4, probably due to an increase in content of the high valence cations of smaller ionic radii, as suggested by an increase in the intensity of the defect band (∼515？cm<SUP>−1</SUP>, IR). The octahedral CrO<SUB>6</SUB> stretching, bending and tilting modes were found shifted accordingly. A mechanism employing a partial-charge model was proposed to explain the results. </P>