A study of the effect of the Cu and Cr co-doping on structural, magnetic and dielectric properties of barium hexaferrites synthesized in presence of mentha leaves extract

In the reported research work, we investigated the structural, thermal, magnetic, surface morphology, Raman spectroscopic and dielectric properties of Cu-Cr co-substituted M-type barium hexaferrites for lossless low-frequency applications. By using the green synthesis approach with mentha leaves extract, we synthesized a series of M-type BaCu<inf>x</inf>Cr<inf>x</inf>Fe<inf>12‐2x</inf>O<inf>19</inf> (0.0 ≤x≤0.5) hexaferrite with varying Cu-Cr content. A simple heat treatment method was used to prepare hexaferrite samples. The samples were heated to 1100 °C and thoroughly characterized for their structural, thermal, magnetic, Raman spectroscopic and low frequency dielectric study. The results of XRD finding revealed the formation of M-phase along with secondary phase of BaFe<inf>2</inf>O<inf>4</inf>. The Raman spectroscopic analysis shows the successful replacement of Cu and Cr ions in place of Fe ions, and the substituted samples hold the hexagonal shape as visible from FESEM images. All samples show a hard magnetic nature with multi-domain structures, and x = 0.2 composition has a maximum M<inf>s</inf> of 68.99 Am²/kg and lowest H<inf>c</inf> of 0.1 T. Cole-Cole graphs show shifting of peaks position with Cu-Cr substitutions and increasing frequency, which gives the insight of the role of grain and grain boundaries. These findings open up exciting possibilities for using these hexaferrites in loss-less, and low-frequency applications.