In this work we report the temperature and doping-level evolution of the crystallographic and magnetic properties of the Sr-doped cobaltates ${\mathrm{Ca}}_{1-x}{\mathrm{Sr}}_x{\mathrm{BaCo}}_4{\mathrm{O}}_7$. The noncollinear ferrimagnetic phase known for the magnetoelectric parent compound is found to persist only for a small amount of Sr doping ($x=0.02$) and is accompanied by a strong unit cell distortion. In turn, further Sr doping blurs this distortion of lattice parameters and favors other magnetic arrangements. In particular, this work focuses on an intermediate temperature region $62\mathrm{K}<T<82\mathrm{K}$ that shows a plateau in the magnetization. Using neutron powder diffraction at selected temperatures and compositions, we have solved the magnetic structure of this intermediate phase. By means of the superspace group theory and its implementation in the Rietveld refinement, we found that the phase belongs to the superspace group $Pna{2}_1{1}^{\prime }(1/2,1/2,g)qq0s$ with a basic orthorhombic structure and a modulation of the magnetic moments along the $c$ axis. The propagation vector is $\mathbf{k}=(\frac{1}{2},\frac{1}{2},g)$ with $g\sim 0.02$ and possibly dependent on temperature. A modulated spin structure with distinct behaviors of the triangular and kagome cobalt sites is reported in “114” cobaltates.

The effect of Zn ²⁺ on the crystal structure, optical properties, and photocatalytic activity for degradation of perfluoroalkyl substances of Bi ₂ WO ₆ was studied.

We have designed and prepared a novel cathode material for solid oxide fuel cell (SOFC) based on SrCo_0.95Ru_0.05O_3−δ perovskite. We have partially replaced Sr by Ba in Sr_0.9Ba_0.1Co_0.95Ru_0.05O_3−δ (SBCRO) in order to expand the unit-cell size, thereby improving the ionic diffusion of O²⁻ through the crystal lattice. The characterization of this new oxide has been studied at room temperature by X-ray diffraction (XRD) and neutron powder diffraction (NPD) experiments. At room temperature, SBCRO perovskite crystallizes in the P4/mmm tetragonal space group, as observed from NDP data. The maximum conductivity value of 18.6 S cm⁻¹ is observed at 850 °C. Polarization resistance measurements on LSGM electrolyte demonstrate an improvement in conductivity with respect to the parent Sr-only perovskite cathode. A good chemical compatibility and an adequate thermal expansion coefficient make this oxide auspicious for using it as a cathode in SOFC.