Effect of milling time on microwave absorption ability on barium-hexaferrite nanoparticles

In this study, Ba_0.6Sr_0.4Fe₁₀MnTiO₁₉ nanoparticles were prepared using solid state reaction method with three milling time variations, 25 hours, 50 hours and 75 hours. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibration sample magnetometer (VSM) and vector network analyzer (VNA) were used to analyze the crystal phases, structure, morphology, static magnetic and microwave absorption properties respectively. The results obtained after three variations of milling time for each sample were a single phase with the hexagonal crystal structure. Grain size decreased with increasing milling time, about 100-150 nm for 25 hours milling time, 75-100 nm for 50 hours and 20-30 nm for milling time of 75 hours. The magnetization saturation Ms reached a maximum of 52.0 emu/g, and the minimum Hc coercivity was 0.32 T for 75 hours milling time. As for 50 hours milling time, Ms = 50.0 emu/g, Hc = 0.34 T and 25 hours, Ms = 44.0 emu/g, Hc = 0.37 T Maximum Reflection Loss (RL) was approximately -49 dB at a frequency 10.8 GHz with bandwidth 1.7 GHz for 75 hours milling time. For a 50 hours milling time the RL value was approximately -33 dB at a frequency of about 11.2 GHz with bandwidth 1.5 GHz and 25 hours milling time the RL value was approximately -20 dB at a frequency 10.9 GHz with bandwidth 1.3 GHz. The average particle size was about 200-350 nm for 20 hours milling time, and RL reflection loss was about - 29 dB at a frequency 12.2 GHz, while for 10 hours milling time, the particle size was about 460 nm, RL reflection loss was about 12 dB at a frequency 9.5 GHz [1].