Preparation and magnetic properties of (Zn-Sn) substituted barium hexaferrite nanoparticles for magnetic recording

Zn-Sn substituted barium ferrite particles BaFe_12-2xZn_xSn_xO₁₉ with O ≤ x ≤ 1.1 have been prepared by a chemical co-precipitation method for the first time. X-ray diffraction (XRD) and transition electron microscopy (TEM) have been carried out to determine the particle structure and morphology. Magnetic properties have been measured using a vibrating sample magnetometer (VSM) with an applied field up to 80 kOe. The specific saturation magnetization M_s was determined using the law of approach to saturation, and the effective anisotropy field H_a and anisotropy constant K₁ were also estimated. It was found that the particle size could be effectively decreased and coercivity H_c easily controlled, by varying x without significantly decreasing saturation magnetization. In particular, BaFe_12-2xZn_xSn_xO₁₉ with x = 0.7-1.1 has suitable magnetic characteristics and a particle size small enough for high-density magnetic recording.