Study of dielectric and magnetic properties with Fe76Si19.4Nb2.7Cu1.7P0.2 ribbons

The as-cast and annealed Fe₇₆Si_19.4Nb_2.7Cu_1.7P_0.2 ribbons with width of 2.5 cm prepared by a single-roller cooling method were investigated. The structural properties of ribbons were studied by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The XRD result shows the α-Fe crystal phase of annealed film. The average crystallite sizes of the as-cast and annealed ribbons are about 28 nm and 43 nm obtained from EF-SEM. The dielectric and magnetic properties of ribbons were tested over frequency ranges of 5 MHz to 300 MHz and 5 MHz to 3000 MHz using an Impedance Analyzer, respectively. The dielectric constant and dielectric loss of the as-cast ribbon decreases from 4.3 × 10⁵ to 180 and from 3.01 to 0.06, while that of annealed ribbon decreases from 2.5 × 10⁴ to 180 and from 3.01 to 1.31. The permeability decreased with increasing frequency at first of each ribbon and the value of annealed ribbon is bigger. It was observed that the permeability loss value of annealed ribbon is smaller at first and then bigger than that of as-cast ribbon. The smallest values of permeability of the as-cast and annealed ribbons are about 1.4 and 1.8. The minimum of the permeability loss of the as-cast ribbon is 0.008. The magnetic hysteresis loops were investigated using a vibrating sample magnetometer. The saturation magnetizations of the as-cast and annealed ribbons are 113 emu g⁻¹ and 123 emu g⁻¹. The coercive fields of the as-cast and annealed ribbons are 259 A m⁻¹ and 1130 A m⁻¹. The saturation magnetization and coercive field could become bigger due to the crystallize property.