Effect of Gd-substitiution on physical and magnetic properties of Li1.2Mg0.4 Gdx Fe(2−x)O4 ferrites

Li1.2Mg0.4 Gdx Fe(2−x)O4 (x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10) ferrites were synthesized by sol-gel auto-combustion technique. Effect of Gd on physical and magnetic properties of Li-Mg ferrites is reported. XRD analysis reveals fcc phase in all the samples along with few traces of second phase. Due to partial solubility of Gd-ions in the lattice, the lattice constant increases initially and then subsequently decreases with the substitution of Gd. It is revealed from M (H)-loops that magnetization follows decreasing trend however coercivity increases with Gadolinium substitution. The decreasing trend of saturation magnetization is attributed to the weakening of exchange interactions. However the increase in coercivity with substitution of Gadolinium concentration is attributed to the presence of an ultra-thin layer at the grain boundaries. This formation of layer subsequently impedes the domain wall motion. Since Li-Mg ferrites have high value of coercivity they can be suitable for high frequency microwave absorption.