Search

The effects of Co doping on structural, dielectric, and magnetic properties of multiferroic 0.6BiFe 1- x Co x O 3 -0.4(Bi 0.5 K 0.5 )TiO 3 (0 ≤ x ≤ 0.2) ceramics have been investigated. The samples undergo a structural transition from pseudocubic to rhombohedral phase at x = 0.1. The maximum remnant polarization of 57.8 μC/cm 2 and remnant magnetization of 0.107 emu/g are observed in the x = 0.15 sample. The ferromagnetism is proposed to originate from the suppression of spiral spin structure with the canting of the antiferromagnetically ordered spins caused by the substitution of Co for Fe ions. Moreover, the magnetodielectric effect can be observed in the x = 0.15 sample. [ABSTRACT FROM AUTHOR]

We investigate the structural, magnetic, ferroelectric, and dielectric properties of Bi 6 Fe 2− x Ni x Ti 3 O 18 (0≤ x ≤1). The coexistence of ferroelectricity and ferromagnetism were observed at room temperature for the Ni-doped samples. The ferromagnetism in Bi 6 Fe 2− x Ni x Ti 3 O 18 can be understood in terms of spin canting of the antiferromagnetic coupling of the Fe-based and Ni-based sublattices via Dzyaloshinsky-Moriya interaction. Moreover, the substitution of Ni for Fe was effective for the enhancement of ferroelectric properties. The x =0.6 sample exhibits a maximum remnant polarization P r of 37.8 μC/cm 2 because of a lower leakage current. The rather large activation energy in the x =0 and 0.2 samples implies that the relaxation process may be not associated with the thermal motion of oxygen vacancies inside the bulk. [ABSTRACT FROM AUTHOR]

Abstract: Anisotropic SmCo5 nanoflakes prepared by high-energy ball-milling with surfactants have great potential in applications for high-performance nanocomposite magnets. For such “nanocomposite” applications, the surface structure and chemistry of nanoflakes are crucial for achieving high coercivity. In this study, hot-pressed samples from anisotropic SmCo5 nanoflakes, ball-milled with different surfactants, oleic acid (OA) and oleylamine (OY), were investigated. Interface layers between the SmCo5 nanoflakes were found to consist of samarium oxides and a soft magnetic Co phase. These surface layers contribute to the degradation of hard magnetic performance, which is confirmed by scanning transmission electron microscopy-energy dispersive X-ray spectroscopy analysis of the cross-section of a single flake ball-milled with OA. Samples milled with OY show a much thinner interface layer in compacted samples, which means that the surface degradation during ball-milling with OY is much less than that with OA. The results show clearly that the choice of proper surfactant and the control of processing parameters are the key factors for improving the surface condition of the nanoflakes and the resulting hard magnetic properties. [Copyright &y& Elsevier]