Micro-extruded LaSrCuFeO-based polystyrene magnetic composites: Morphological and magnetic characterization

Novel magnetic composites consisting of a polystyrene matrix containing LaSrFeCuO (LSFC10) and LaSrFeCuO (LSFC20) particles, each with two weight concentrations, 0.5% and 1.0%, are prepared by extrusion technique. The LSFC10 and LSFC20 filler phases are synthetized by citrate auto-combustion technique. From the XRD data, only a single crystalline phase, namely an orthorhombic perovskite structure, is observed. Additionally, the TEM images and EDX analysis show single phase compounds, confirming the absence of other phases. SEM images of the composites show the presence of perovskite nanoparticles, aggregated in structures with dimensions in the order of ten microns or lower, probably due to their magnetic interactions. Differently to bare particles, showing a single-phase hysteresis loop, the room temperature field-dependent magnetization loops of polymer composites exhibit a wasp-waisted-like magnetic hysteresis loops, which may origin from different mechanisms that likely emerge when the particles are dispersed in the matrix, such as the particle surface spin canting and the interparticle interactions, along with a physical rotation of the particles that are not firmly blocked in the polymer matrix.