Structure and magnetic properties of multi-layered ZrO2 nanoparticles embedded in Al2O3 matrix and doped with 57Fe3+ ions

The multi-layered 3-8 nm ZrO2 particles doped with Fe-57(3+) ions were synthesized by successive impregnations of Al2O3 with a solution of Zr isopropoxide and Fe-57 acetylacetonate. This gave (Fe-ZrO2)/Al2O3 samples containing ZrO2 (approximate to 30 mass%) and different Fe content (0.06-0.26 mass%). By means of XRD, TEM and EDS techniques, it was found that the size of ZrO2 nanoparticles in the (Fe-ZrO2)/Al2O3 samples increases in proportion to the Fe content. According to magnetic measurements and Mossbauer spectroscopy data, (Fe-ZrO2)/Al2O3 samples contain two types of paramagnetic high-spin Fe-57(3+) ions. The Fe-57(3+) ions of type (I) are most probably adsorbed on the outer surface of ZrO2 nanoparticles and are responsible for the spin-lattice relaxation observed in the (Fe-ZrO2)/Al2O3 samples. The Fe-57(3+) ions of type (II) are embedded in the bulk of ZrO2 nanoparticles by replacing the octahedral Zr4+ positions to give a mixed oxide. As the Fe content in the (Fe-ZrO2)/Al2O3 samples increases, the fraction Fe-57(3+) ions of type (I) decreases, while that of Fe-57(3+) ions of type (II) increases. (C) 2016 Elsevier B.V. All rights reserved.