Unusual magnetic behaviors and electrical properties of Nd-doped BiFeO3 nanoparticles calcined at different temperatures
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Bi1−x Nd x FeO3 (x = 0, 0.05, 0.1, 0.15, 0.2) nanoparticles (about 20–50 nm) calcined at 500 and 600 °C, respectively, were prepared by an ethylene glycol-based sol–gel. The XRD analysis reveals that the BiFeO3 samples are in single phase, and their crystal structure is varied with the Nd content. Due to the small particle size, the uncompensated spin moments on the surface and the suppression of spin helical ordering structure result in a ferromagnetic phase of the BiFeO3 nanoparticles. The magnetization of the Nd-doped samples calcined at 600 °C is improved with the increase of Nd content, but for the Nd-doped samples calcined at 500 °C, it shows an opposite trend, which is ascribed to the interplay of size effect and the ratio of Fe2+:Fe3+ of samples calcined at different temperatures via XPS analysis. The dielectric properties were measured and analyzed for the samples calcined at 500 and 600 °C. Moreover, the leakage current value of the Bi1−x Nd x FeO3 samples can be modulated by the Nd doping, and it reaches a minimum at the Nd content around 0.1.
KeywordsNanoparticles Ferromagnetic Spin helical ordering structure Dielectricity Leakage current Synthesis
This study has been supported by the National Natural Science Foundation of China (11004148, 51074112, 11104202) and the Natural Science Foundation of Tianjin (11JCYBJC02700, 11JCZDJC21800).