Fabrication of Bi3+ substituted yttrium aluminum iron garnet (YAIG) nanoparticles and their structural, magnetic, optical and electrical investigations

In this work, Y 3−x Bi x Al 0.5 Fe 4.5 O 12 nanoparticles in powder form with composition x = 0.0, 0.5, 1.0,1.5 and 2.0 were fabricated by a sol–gel auto-combustion technique and calcined at 1150 °C for 10 h. The analysis of X-ray diffraction patterns using Rietveld refinement suggests that Bi-substituted yttrium aluminum iron garnet (YAIG) samples crystallize in cubic structure with Ia- 3 ¯ d space group. The average size of crystallite of the samples calculated by the Scherer formula is found in the range of 19–24 nm which are in consistent with that of measured from Williamson–Hall curve. The absorption bands in Infrared spectra corresponding to garnet are shift to lower frequency with the increase of the Bi 3+ concentration. Raman spectroscopy shows the non-vibrational behavior of Bi-substituted YAIG due to the excitation of Y 3+ ions from the ground energy level. The morphology of the samples is observed by transmission electron microscopy and field emission scanning electron microscopy which showed most of the particles and grains are in spherical shape. The energy dispersive X-ray (EDS) spectra confirmed the elemental compositions of the selected sample. In UV–Visible spectroscopy, transparency of the samples decreases with increasing in Bi 3+ ions substitution in YAIG. The saturation magnetization (Ms) decrease from the 14.59 to 2.25 emu/g with the increase in Bi 3+ ions concentration, whereas, the values of coercivity (Hc) and retentivity (Mr) are very low. DC resistivity as a function of temperature shows the semiconducting nature of the synthesized samples and its decreased from 6.17 × 10 6 to 0.06 × 10 6 Ω-cm with the addition of Bi 3+ ions.