Dielectric and magnetic characterization of barium hexaferrite ceramics

Barium hexaferrite (BHF) was obtained by high energy ball milling using milling power of 4:1 and 10:1 and milling times of 1 h and 10 h, hereinafter referred to as BHF411, BHF4110, BHF101 and BHF1010, respectively. After sintering at 1200 °C, the products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The magnetic and dielectric properties were examined using a permeameter (8.4 kOe) and an impedance analyzer (300 MHz-1.1 GHz), respectively. The properties of coercivity and magnetic saturation of the BHF41 samples increased with milling time, but decreased over time for BHF101. At low frequencies, both BHF41 samples showed a slight variation in relative permittivity (ε׳), but this property remained almost constant at high frequencies. On the other hand, the initial permittivity of BHF101 samples varied significantly at low frequencies, but was almost constant at high frequencies. All the BHF samples showed a decreasing behavior of tanδ at the highest frequencies.