Effect of Cr³⁺ substitution on AC susceptibility of Ba hexaferrite nanoparticles

In this study, nano-sized particles of BaCrxFe12−xO19 (0.0 ≤ x ≤ 1.0) hexaferrite were fabricated through citrate auto gel combustion process and the impact of Cr-ion substitution on ac magnetic susceptibility properties of Ba-hexaferrite were explored. X-ray powder diffraction (XRD) measurements approved the purity of prepared samples and showed a reduction of the average crystallite size with increasing the content of Cr. Transmission electron microscopy (TEM) observation indicated the hexagonal morphology of all samples. AC susceptibility measurements displayed a frequency dependence of the magnetic responses. These measurements indicated that there are strong magnetic interactions (which is the highest for BaCr0.3Fe11.7O19 NP) between particles which cause a superspin glass-like (SSG) behavior at low temperatures. Estimating the values of loss power density revealed an increase of loss power density with increasing Cr-substitution element. The relative sensitivity of the prepared MNPs to the variation of applied frequency is very influenced by Cr-substitution and is highest in BaCr0.3Fe11.7O19 MNPs, suggesting that this sample can be considered as magnetic nanomaterial for hyperthermia and for many other applications.