Influence of the Eu substitution on the structure and magnetic properties of the Sr-hexaferrites

摘要

Europium (Eu)-substituted M-type strontium hexaferrites (SrEuM) have been synthesized successfully by using a solid-state reaction method. The crystal structure, valence state, element distribution and temperature-dependent magnetic properties are investigated systematically. The single-phase polycrystalline form of SrFe12O19 can be obtained until the substitution reached 0.10, as exhibited in XRD patterns. All samples display the hexagonal platelet-like shape, and the morphology becomes increasingly mellow and full with rising Eu substitution. A significant improvement of saturation magnetization (M-s) and intrinsic coercivity (H-c) at ultralow and room temperatures are achieved under the substitution effort. The origin of this behavior is explained fully from the occupancy and spin orbit in the hexagonal structure system. Moreover, the analysis of thermal characteristics indicates a superior performance in quality and thermal stability as reflected in DSC-TGA curves. SrEuM will be widely used in the magnetic field for the advantage of the high Curie temperature (T-c = 734K).