A comparison of soft magnetic composites designed from different ferromagnetic powders and phenolic resins

Soft magnetic composites （SMCs） were prepared from three different ferromagnetic powder particles： iron powder ASC 100.29, spherical FeSi particles and vitroperm （Fe73CulNb3Si16B7） flakes. Two types of hybrid organic-inorganic phenolic resins modified with either silica nanoparticles or boron were used to design a thin insulating layer perfect- ly covering the ferromagnetic particles. Fourier transform infrared （FTIR） spectrometry confirmed an incorporation of silica or boron into the polymer matrix, which manifested itself through an improved thermal stability of the hybrid resins verified by thermogravimetric-differential scanning calorimetry （TG-DSC） analysis. The core-shell particles prepared from the ferromagnetic powder particles and the modified hybrid resins were further compacted to the cylindrical and toroidal shapes for the mechanical, electrical and magnetic testing. A uniform distribution of the resin between the ferromagnetic particles was evidenced by scanning electron microscope （SEM） analysis, which was also reflected in a rather high value of the electrical resistivity. A low porosity and extraordinary high values of mechanical hardness and flexural strength were found in SMC consisting of the iron powder and phenolic resin modified with boron. The coercive fields of the prepared samples were comparable with the commercial SMCs.

Structural and mechanical properties of La_(1/3)NbO_3 and La_(1/3)TaO_3 thin films prepared by chemical solution deposition

In this work, properties of perovskite lanthanum niobate La1/3NbO3(LN) and tantalate La1/3TaO3(LT)transparent thin films(200 nm thickness) prepared by chemical solution deposition on Pt/SiO2/Si substrates were described. The precursors and films were analyzed using FTIR and XPS spectra, XRD and SEM imaging. The both films after annealing at 1100 ℃ contained perovskite phase with a small fraction of pyrochlore LaNb5O14(in LN). The heterogeneous micro structure of LN film was composed from spherical or needle-like particles and homogeneous LT film that resulted in significant changes of their mechanical properties. The elastic modulus and hardness of these films were characterized for the first time by conventional and continuous stiffness(CSM) nanoindentation. The LT film modulus(E) and hardness(H) were higher(105.7 and 5.3 GPa) than LN(91.5 and 3.8 GPa). The effect of microstructure on mechanical properties is significant. In addition, the average Derjaguin-Muller-Toporov(DMT)-based elastic modulus of LN film surface were estimated50 GPa using AFM PeakForce QNM elastic mapping. The findings presented here can contribute to the fabrication of LN and LT films for the application to electrolytic thin film devices.