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 (ρx-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 (Ea) and drift mobility (μd) are also calculated from the resistivity data. The dielectric constant (ε') and dielectric loss (tan δ) have been measured in the frequency range of 80 Hz-1 MHz. The magnetic properties such as saturation magnetization (Ms), remanence (Mr) and coercivity (Hc) are calculated from the hysteresis loops. Values of ε', tan δ, Ms, Mr and Hc are found to decrease with increase in Al-Ga concentration