Structural, magnetic, dielectric and high frequency response of synthesized rare earth doped bismuth nano garnets (BIG)

Abstract

Rare earth doped bismuth (Bi) iron garnets (BIG) having composition Bi3−xRxFe5O12 for x = 1.5 (here R stands for rare earth elements like Y, Gd, Pr, Ho and Yb) have been studied in this work. The samples were prepared using sol-gel method. X-Ray diffraction (XRD), Scanning electron microscope (SEM), Fourier transform infrared spectroscope (FTIR), Vibrating sample magnetometer (VSM) and Vector network analyzer (VNA) were employed on the samples to evaluate the properties of the doped Bi nanogarnets. Single-phase garnet structure was confirmed through XRD and the crystallite sizes were found to be 66–73 nm, depending upon the type of rare earth ions. SEM images helped to observe the morphology and measurement of grain size of the doped Bi nanogarnets. Vibrational bands showed the presence of garnet phase and were confirmed through FTIR analysis. Detailed dynamic magnetic and dielectric properties were measured using VNA from 1 to 6 GHz. Real and imaginary part of the permittivity, permeability, dielectric and magnetic losses, ac conductivity, electric modulus and Q factor were calculated for the rare earth doped Bi nanoferrites. Gd doped Bi nanoferrites showed higher permittivity values whereas Pr doped show higher ac conductivity as compared to other samples. Yb doped Bi nanoferrites have Q factor values at 4.8 GHz. Static magnetic properties of the doped Bi nanogarnets were investigated using magnetic loops. Magnetic remanence (Mr) Saturation magnetization (Ms) and coercivity (Hc), Bohr magneton, anisotropy constant and initial permeability were also calculated. The dielectric and magnetic studies of the rare earth doped Bi nanogarnets suggested the applications of these rare earths doped nanogarnets for microwave devices and high frequency applications in GHz regime.