Enhanced magnetic and structural properties of functional hard/soft ferrite nanocomposites for microwave application

Abstract

Hard/soft ferrites nanocomposites are a new intelligent generation of magnetic materials that hold great potential in various applications particularly microwave applications owing many unique properties such as high microwave absorption ability. The integration between the hexaferrite (hard) (H) (MFe12O19, M= Sr, Ba, and Pb) and the spinel ferrite (soft) (S) (MFe2O4, M= Ni, Co, Zn, or other elements ) are tuned the magnetic properties by combining a high magnetic saturation (Ms) property related to the soft part with a high magnetic coercivity (Hc) property related to the hard part. This combination will generate the exchange-coupling behavior that included two main interactions, which are the exchange and dipolar. These two interactions have been fundamentally playing an important role in forming the magnetic characteristics in H/S ferrites nanocomposites. The thesis objective is to establish various sets of novel hard/soft ferrite nanocomposites (NCs) {SrTb0.01Tm0.01Fe11.98O19/AFe2O4 (A= Co, Ni, Zn, Cu and Mn); SrTb0.01Tm0.01Fe11.98O19/(CoFe2O4)x (0.00 ≤ x ≤ 0.03); SrFe12O19/x(CoTm0.01Tb0.01Fe1.98O4) (1.0 ≤ x ≤ 3.0); SrNi0.02Zr0.02Fe11.96O19/MFe2O4 (M= Mn, Co, Cu, and Zn); SrNi0.02Zr0.02Fe11.96O19/(CoFe2O4)x (1.0 ≤ x ≤ 3.0); Sr0.5Ba0.5ScxFe12-xO19 /NiFe2O4 (x ≤ 0.035); and SrInxFe12-xO19/Ni0.5Zn0.5Fe2O4 (0.00 ≤ x ≤ 0.04)} by using “one-pot” sol-gel auto-combustion process and investigate their structural, magnetic, and microwave properties for the potential of using them as microwave absorbers. Moreover, the effect of substitution the transition metals (Ni2+, Zr4+, Sc3+, and In3+) and rare earth elements (Tb3+and Tm3+) on the structure of hard/soft ferrite, the changing of spinel ferrite type, and the increasing of soft phase amount; into the characteristics of prepared nanocomposites were studied.