Microstructure and magneto-acoustic oscillations of (Cu, Co) nickel ferrite

Effects of the microstructural features as revealed by scanning and transmission electron microscopy on the magnetostrictive vibration of Cu and Co doped NiFe2O4are studied. Results show that changes in the grain size are strongly coupled with the geometry of the pores and the two features are not separable. The magneto-mechanical coupling coefficient is seen to depend strongly on the grain size. However, it appears that the pore structure and not the grain size is the important microstructural parameter that affects this magnetic property. Additional evidence is presented to show the importance of the pore geometry. Effects of microstructural features such as stacking faults, dislocations, nickel phosphide precipitates on grain boundaries, etc. are shown to be secondary in importance.