Grain orientation distributions of polycrystalline co-ferrite

Magnetostrictive materials suitable for high sensitivity strain sensor and ultrasonic transducer have increasingly attracted researchers´ interest recently. Nonmetallic magnetostrictive materials based on Co-ferrite are excellent candidates for rare earth giant magnetostriction materials for the unique advantages of high strain sensitivity, high electrical resistivity, low cost, chemical and thermal stability. Studies about effects of elements doping and magnetic tempering in magnetic properties of co-ferrite have been widely carried out. Results show that these methods are very efficient to get high magnetostriction and strain sensitivity. As is well-known, the macro magnetostriction of polycrystalline Co-ferrite was statistical values of all isotropically distributed grain. The study of grain orientations in polycrystalline Co-ferrite could help to further increase magnetostriction and strain sensitivity. In this work, the characterization about grain orientation distributions of polycrystalline Co-ferrite has been studied and an interesting phenomenon also has been shown. Pure CoFe₂O₄ were prepared by mixing Co₃O₄ and Fe₂O₃ at stoichiometric ratio, calcining at 900 and sintering at 1350. The microstructures and orientation imaging microscopy of the samples were studied using the Scanning Electron Microscope (SEM) and Electron Backscattering Diffraction (EBSD), respectively. Magnetostriction was measured parallel to the applied field at room temperature using piezo-resistive strain gauges attached to the samples which were cylindrical with diameter 10mm and height 30mm.