LAUSR

Abstract The precursors of ZrO 2 -MgO system covering the whole concentration range were prepared by co-precipitation of the corresponding nitrate salts. The obtained precursors were calcined in air at different temperatures up to 1000 °C and analyzed at room temperature using X-ray powder diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESM) and energy dispersive X-ray spectrometry (EDS). Maximum solubility of Mg 2+ ions (∼32 mol%) was obtained in the amorphous precursor. After crystallization at 600 °C the solid solubility of Mg 2+ ions decreases to ∼26 mol% of which ∼22 mol% was incorporated inside ZrO 2 -type lattice while the remaining part of Mg 2+ ions was adsorbed on the surface of the particles. Further thermal treatment decreases solubility of Mg 2+ ions to 18 mol% (800 °C) and finally to 9 mol% (1000 °C). On the other side of the concentration range, the solubility of Zr 4+ ions in MgO lattice was 2+ ions partially stabilized both tetragonal ZrO 2 (up to 10 mol%) and cubic ZrO 2 (>10 mol%) polymorphs. A precise determination of unit-cell parameters shows that the increase in the Mg 2+ content causes a decrease in the parameter c of tetragonal ZrO 2 lattice, which in a solid solution with a Mg 2+ content ≥10 mol% becomes very close to the lattice parameter a (approaching cubic lattice). The results of FE-SEM analysis show that the addition of Mg 2+ ions promotes sintering of samples. The influence of thermal treatment on the crystallization of the amorphous precursors to ZrO 2 -type lattice was examined by differential thermal analysis and thermogravimetric measurement. The obtained results show that the crystallization temperature increases with increasing Mg content, from 445 °C (0 mol% MgO) to 625 °C (∼50 mol% MgO). The ZrO 2 doped with 3 mol% MgO was used as catalyst support for platinum nanoparticles and compared to commercially available 3% yttria-doped stabilized zirconia (3YSZ). The catalysts were used for catalytic CO oxidation and show slightly better performance of the ZrO 2 -MgO system, which demonstrates the potential of these materials as alternative catalyst support.