Tuning the Magnetic Properties of Hard–Soft SrFe₁₂O₁₉/CoFe₂O₄ Nanostructures via Composition/Interphase Coupling

High Resolution Image Download MS PowerPoint Slide Magnetic nanocomposites (NCs) are extremely appealing for a wide range of energy-related technological applications, specifically as building blocks for next-generation permanent magnets. The design of such nanostructures requires precise chemical synthesis methods, which will permit the fine-tuning of the magnetic properties. Here we present an in-depth structural, morphological and magnetic characterization of ferrite-based nanostructures obtained through a bottom-up sol–gel approach. The combination of the high coercivity of a hard phase SrFe 12 O 19 (SFO) and the high saturation magnetization of a soft phase, CoFe 2 O 4 (CFO), allowed us to develop exchange-coupled bimagnetic NCs. A symbiotic effect is observed in a SFO/CFO nanocomposite, as the unique oriented growth of SFO prevents grain growth of the CFO, thus restricting the crystallite size of both. Through X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), and magnetic measurements we clarify the relationship between the distribution and size of hard/soft particles, the optimization of interfaces and the obtained uniform magnetic response. This study allowed us to establish the potentiality of hard/soft SFO/CFO nanostructures in current permanent magnet technology.