The impact of Yb and Co on structural, magnetic, electrical and photocatalytic behavior of nanocrystalline multiferroic BiFeO3 particles

Abstract

The nanocrystalline particles of BiFO3,co-doped with ytterbium and cobalt Bi1−xYbxCoyFe1−yO3 (BYCFO) were fabricated via micro-emulsion method using cetyltrimethyl ammonium bromide (CTAB) as a surfactant. The dopant contents were kept x = 0.00, 0.025, 0.05, 0.075, 0.1, 0.125 and y = 0.00, 0.05, 0.1, 0.15, 0.2, 0.25 for six different compositions. The BYCFO-nanoparticles were investigated for structure, electric, dielectric, magnetic and photocatalytic properties. The X-ray diffraction (XRD) analysis confirmed the normal growth habitat Rhombohedral (R3c) phase on inclusion of ytterbium and cobalt ions as it is observed in undoped BiFeO3 multiferroic. However further doping of Yb+3 and Co+3 ions (x = 0.125, y = 0.25) resulted in some extra peaks, that is attributed to the formation of extra phase. The vibrating sample magnetometer recorded saturated magnetization (Ms) 0.385emu/g with remanent magnetization (Mr) 0.13emu/g for a coercivity of 405Oe which is higher than the undoped BiFeO3. The substitution of Yb+3 and Co+3 ions improved the canting angle and optimally aligned the sub lattices in ferromagnetic order. The grain size was found in the range of 20–24nm which is less than spiral spin modulation (≈ 62nm). The entire dielectric parameters showed smooth decreasing trend in low range frequency but at higher frequency (1.98GHz) resonance peaks appeared in the spectra. The insulating character was also enhanced up to 16.42 × 1010Ωcm−1, with increase in doping concentrations. The optical band gap was measured 1.5eV which was lower than the undoped BiFeO3 (2.15eV). The photocatalytic performance of co doped ceramic (Bi0.875Yb0.125Co0.25Fe0.75O3) was monitored using the textile dye Congo red. Approximately 28% of initial concentration (0.5ppm) was degraded by 200mg of ceramics in 42min under visible light irradiation. Being magnetic in nature, the Bi1−xYbxCoyFe1−yO3 particles could be separated by conventional magnetic bar.