Effects of Fe doping and the dielectric constant on the room temperature ferromagnetism of polycrystalline CeO2 oxides

Abstract

Impact of sintering temperature on the physical properties of the superconducting ferromagnet: Ru Sr 2 Eu 1.5 Ce 0.5 Cu 2 O 10 Ce 1−x Fe x O 2−␦ polycrystalline samples with x = 0% -8% were synthesized by the solid phase reaction method at a low sintering temperature of 1250°C, and the effect of Fe content on the magnetic behaviors has been systemically investigated. It is found that the pure CeO 2 samples are diamagnetic, while doped samples unambiguously show the existence of room temperature ͑RT͒ ferromagnetism ͑FM͒. With the increase in x, the saturation magnetization ͑M s ͒ exhibits a steep increase to a maximum M s of 1 emu/g at x = 2.7% and then drop exponentially. A small amount of Fe doping ͑0.9%͒ promotes the densification and induces a large dielectric constant ͑͒. Our result shows that a relatively large and a proper Fe concentration are critical to establish the magnetic polaron and provide strong RT FM in CeO 2 .

Enhanced Room-Temperature Ferromagnetism on Co-Doped CeO2 Nanoparticles: Mechanism and Electronic and Optical Properties

“…Recently, Coey et al proposed a model to explain the observed ferromagnetism, based on impurity-band exchange and density-functional calculations by considering the oxygen-defect-induced donor sites. In the F-center-mediated mechanism, the radius of the electron orbital is a direct function of the dielectric constant . Since CeO 2 has a high dielectric constant of 26, the radius of the F-center electrons may be large enough to produce magnetic interactions at low Co concentrations.…”

“…In the F-center-mediated mechanism, the radius of the electron orbital is a direct function of the dielectric constant. 35 Since CeO 2 has a high dielectric constant of 26, the radius of the F-center electrons may be large enough to produce magnetic interactions at low Co concentrations. As x increases to 0.04, a fraction of the Co ions are likely to enter the interstitial positions which require an excess of oxygen ions for charge neutrality.…”

Fe doping induced enhancement in room temperature ferromagnetism and selective cytotoxicity of CeO2 nanoparticles

“…fact that Fe doping into CeO 2 matrix lead to enhanced level of oxygen vacancies which will lead to more exchange integrations with Ce 3+ and enhanced magnetization [25,26]. Moreover, the doped Fe 3+ ions can also lead to enhanced magnetic characteristics via same exchange interaction (i.e.…”

Weak Ferromagnetism in a One-Orbital Double-Exchange Model with Ising Spins for Cerium Oxides

“…The anti-oxidative properties of cerium oxides are attributed to the coexistence of Ce 3+ and Ce 4+ oxidative states of the cerium atom, which is is controlled by oxygen deficiencies. Even though the electronic structure of cerium oxides is relatively poor in electrons (compared to other rare and transition metal oxides), there have been reports of room temperature magnetism in these materials [12][13][14][15][16][17][18][19]. For a more comprehensive list, please see [20] and references therein.…”