Effect of Sn4+–Zn2+–Co2+ Doping on Structural and Magnetic Properties of M-Type Barium Hexaferrites

Barium hexaferrite and synthesized components by the combination of Co–Zn–Sn ions were prepared using sol–gel auto-combustion method. To complete the combustion process, a microwave oven was used, obtaining the finest powder. An X-ray diffractometer (XRD) revealed the formation of an M-type hexagonal structure with the P6₃/mmc system. Different lattice parameters including <inline-formula> <tex-math notation="LaTeX">${a}= {b}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">${c}$ </tex-math></inline-formula> and their changes were obtained via XRD peaks. According to Scherrer’s equation, enhancing dopant concentrations led to increases in <inline-formula> <tex-math notation="LaTeX">${a}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">${c}$ </tex-math></inline-formula> around 3.94–3.97 Å, which referred to the influence of substituents on crystallographic lattices, and the average crystal size was around 62 nm. Proving the synthesis process of hexaferrite, Fourier-transform infrared spectrum was observed to be around 400–600 and 1440 cm⁻¹ that revealed the stretching band of Fe–O. Magnetic properties and morphology were described using vibrating sample magnetometer and field-emission scanning electron microscopy (FESEM), respectively. FESEM micrographs represent the hexagonal structure of prepared samples with the average grain size in the nanometer range (120 nm). Finally, from hysteresis loops, it was understood that the highest amount of saturation magnetization (<inline-formula> <tex-math notation="LaTeX">${M} _{\mathbf {s}}$ </tex-math></inline-formula>) belonged to the sample <inline-formula> <tex-math notation="LaTeX">${x}= 0.5$ </tex-math></inline-formula> (about 52.33 emu/g), which shows the pure phase but by increasing more substitutions, it decreased. The amount of <inline-formula> <tex-math notation="LaTeX">${H} _{\mathbf {c}}$ </tex-math></inline-formula> reduction was related to the magnetic behavior of substituted dopants and nanoparticles size.