Synthesis, physical, magnetic and electrical properties of Al-Ga substituted co-precipitated nanocrystalline strontium hexaferrite

A series of Al-Ga substituted strontium hexaferrite materials of nominal composition SrAlxGaxFe12-2xO19( x = 0.0 - 0.8) have been synthesized by the co-precipitation method. The XRD analysis confirms the single magnetoplumbite phase and various parameters such as lattice constants (c and a), cell volume (V), crystallite size ( D) and X-ray density (rho(x- ray)) have also been calculated from the XRD data. The crystallite size is found in the range of 30 - 62 nm. The elemental composition is determined by EDX analysis. DC electrical resistivity is measured within the temperature range of 300 - 675 K. It is observed that the resistivity increases with the Al-Ga content. The activation energy (E-a) and drift mobility (mu(d)) are also calculated from the resistivity data. The dielectric constant (epsilon) and dielectric loss (tan delta) have been measured in the frequency range of 80 Hz-1 MHz. The magnetic properties such as saturation magnetization (M-s), remanence (M-r) and coercivity (H-c) are calculated from the hysteresis loops. Values of epsilon, tan delta, M-s, M-r and H-c are found to decrease with increase in Al-Ga concentration. (C) 2007 Elsevier B. V. All rights reserved.