The structural and magnetic properties of BaFe12O19 nanoparticles: effect of residual sodium ions. Issue 41 (13th October 2021)

• Record Type: Journal Article
• Authors: Choi, Jae-Young; Lee, Jeong-Min; Baek, Youn-Kyung; Lee, Jung-Goo; Kim, Young-Kuk
• Is Part Of: Dalton transactions. Volume 50:Issue 41(2021)
• Page Start: 14560
• Page End: 14565
• Publication Date: 2021-10-13
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1dt02745j
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The magnetic properties of BaFe12 O19 nanoparticles can be enhanced by doping with Na ions via formation of oxygen vacancies and further evolution of magnetic interactions. Abstract : We studied the structural and magnetic properties of BaFe12 O19 (BaM) nanoparticles synthesized by a co-precipitation route based on a modified citrate process. The lattice contraction of co-precipitated BaM nanoparticles is detected after prolonged sintering at 900 °C. In addition, investigation with X-ray photoelectron spectroscopy (XPS) provides evidence of a highly enhanced population of oxygen vacancies. The lattice distortion and formation of oxygen vacancies are attributed to a direct result of substitutional incorporation of smaller Na ions into Ba 2+ sites in the lattice of BaM during prolonged annealing. The aliovalent impurities are assumed to be originated from NaOH which has been incorporated as a pH modifier. Magnon scattering is detected at 1640 cm −1 in the low temperature Raman spectra of BaM. Minimization of the magnon peak is also identified after prolonged annealing, which indicates oxygen vacancy-induced collapse of strong anti-ferromagnetic interaction between Fe 3+ ions in the bipyramidal sites and the octahedral sites in BaM nanoparticles. As a result, the saturation magnetization ( M s ) of BaM nanoparticles is enhanced by the onset of local ferromagnetic interaction induced by the collapse of antiferromagnetic interaction between oppositely aligned spins. In this study, we re-investigated the evolution of structural and magnetic properties with prolonged annealing of BaM nanoparticles and the effects of residual Na ions are also discussed.