Effect of plasma treatment on magnetic properties and heating efficiency of Ni-Zn nanoparticles

The magnetic properties and AC heating characteristics of Ni_1-xZn_xFe₂O₄ nanoparticles were investigated. Magnetization measurements conducted on various sample compositions revealed that the magnetization of the nanoparticles was maximum for x = 0.75 sample. Ni_0.25Zn_0.75Fe₂O₄ nanoparticles were exposed to plasma for 30 min. The resultant, magnetization (M), blocking temperature (T_B), superparamagnetic transition temperature (T_m), heating temperature, and specific absorption rate (SAR) of Ni_0.25Zn_0.75Fe₂O₄ nanoparticles before and after plasma treatment showed that the plasma treatment enhanced the magnetic and thermal properties. To determine the improved characteristics in more detail, we obtained Mössbauer spectra at various temperatures. Analysis of the Mössbauer spectra of Ni_0.25Zn_0.75Fe₂O₄ nanoparticles revealed two sets of six lines for tetrahedral (A) and octahedral (B) sites. Also, Mössbauer spectra with an external field up to 1 T were performed and the spin canting angles in Ni_0.25Zn_0.75Fe₂O₄ before and after plasma treatment were determined.