Absence of ferromagnetism in Mn- and Fe-stabilized zirconia nanoparticles

In order to experimentally check the recent theoretical prediction regarding the Mn- or Fe-doped cubic ZrO2 as potential spintronic materials and to search for high-temperature ferromagnetic spintronic material, a series of Zr1−xMnxO2 (x=0.15–0.35) and Zr1−xFexO2 (x=0.15–0.40) nanoparticles were prepared by a coprecipitation method. The crystal structure and magnetic properties of the compounds were investigated by means of X-ray diffraction, transmission electron microscopy (TEM) and magnetic measurements. Detailed structural analysis confirmed that single phase of Mn- and Fe-stabilized cubic zirconia was obtained. The solubility limit of Mn (or Fe) in ZrO2 is about x=0.27 (or 0.36). Magnetic measurements showed that all the samples were paramagnetic at room temperature and 5 K. Existence of antiferromagnetic interactions in the samples was inferred from the fitting of magnetization data to the Curie–Weiss law. The absence of ferromagnetism could plausibly be attributed to an excess of oxygen vacancies in the Mn- or Fe-stabilized cubic zirconia.