Characterization and magnetic properties of NdxBi1−xFe0.95Co0.05O3 nanopowders synthesized by combustion-derived method at low temperature

NdxBi1−xFe0.95Co0.05O3 (x=0, 0.05, 0.10, 0.15) nanopowders were prepared by a combustion-derived method. The Rietvelt fitting of the X-Ray diffraction data from the NdxBi1−xFe0.95Co0.05O3 (NBFCO) powders showed nanopowders with rhombohedral BiFeO3 crystalline structure (R3c) for x≤10 and a partial structural transition to orthorhombic phase (Pnma) for x=0.15. The differential thermal analysis and thermogravimetric analysis (DTA/TGA) showed a crystallization temperature of 180 °C. Transmission electronmicroscopy (TEM) images revealed that the NBFCO nanopowders were composed of fine particles under 60 nm. From Raman spectroscopy, a band of disordered anion lattice was observed at 653 cm−1. In spite of the antiferromagnetic nature of bulk BiFeO3, the NBFCO nanopowders obtained displayed a ferromagnetic hysteresis loop, with coercivity about 0.1 T and remanent magnetization of 1.02-4.33 A m2/kg were obtained at room temperature. This ferromagnetic behavior is due to increasing and uncompensated spins at the surface and the canted internal spin by the tilt of FeO6 octahedral units. We have developed a novel synthetic route for the preparation of ferromagnetic BFO-derived nanopowder materials by a surfactant-assisted combustion-derived method.