Effect of Ni and Dy co-doping on the structural, electrical, and dielectric properties of Strontium Y-type hexaferrite

Strontium Y-type hexaferrites, often referred to as Sr-Co₂Y hexaferrites, are widely considered for the microwave applications. The current study describes the synthesis of Ni and Dy-doped Sr Y-type hexagonal ferrites i.e., Sr_2-xDy_xCo₂Ni_yFe_12-yO₂₂ (x = 0–0.03 and y = 0–0.3) by utilising the sol-gel (SG) process. The hexaferrite powders were sintered for 4 h at 1150 °C to eliminate impurities and moisture. The room temperature (RT) DC resistivity ( \(\rho\) $\rho$ ) of the Sr hexaferrites increases as the temperature and the Ni²⁺/Dy³⁺ content increase. This shows the semiconducting nature of Sr-Co₂Y hexaferrites. The Ni²⁺ and Dy³⁺ doping reduces the drift mobility (μ_d) but increases the activation energy (E_a). The observed E_a for the Sr hexaferrite materials showed the same trend as that of \(\rho\) $\rho$ . The dielectric analysis was performed within the frequency range of 82 Hz–10 MHz. Both the real permittivity (ε′) and the loss tangent (tanδ) drop as the applied frequency rises. The dielectric properties also decrease after Ni and Dy substitution. The increase in \(\rho\) $\rho$ together with the small dielectric loss makes these hexaferrite materials more effective for devices and applications requiring high resistive and high-frequency materials.