Two-step combustion synthesis of nanocrystalline Zn$_{1-x}$Mn$_x$Fe$_2$O$_4$ ($0\le x\le1$) spinel ferrites with linear tuning of magnetic parameters

Multicomponent zinc ferrites are of great applied value due to their functional features, due to which they are widely used in the production of microwave devices. In this regard, the development of new methods for obtaining initial preceramic nanopowders in a nanostructured form is especially urgent. In this work, multicomponent zinc-manganese ferrites of the Zn$_{1-x}$Mn$_x$Fe$_2$O$_4$ ($x=0, 0.2,\dots,1.0$) composition were obtained by thermal treatment of X-ray amorphous products of solution combustion synthesis at a temperature of 750$^\circ$ C and a holding time of 6 hours. The synthesized powders were analyzed by PXRD, FT-IR, and SEM methods. The magnetic characteristics were determined by vibration magnetometry. It was shown that the obtained samples contain one-phase spinel ferrite without any noticeable impurities. Depending on the number of Mn$^{2+}$ cations in the crystal lattice, the unit cell parameters varied from 8.485(2) to 8.451(2) $\mathring{\mathrm{A}}$. The average crystallite size of the powders varied from 29.4 nm in the case of zinc ferrite to 36.8 nm in the case of MnFe$_2$O$_4$. Residual magnetization $(M_s)$, saturation magnetization $(M_r)$, and coercive force $(H_c)$ also depend on the content of manganese cations in spinel and variedfrom 4.9 to 12.3 emu/g, from 22.4 to 76.4 emu/g, and from 47.5 to 81.3 Oe, respectively and these dependencies are almost linear. The highest magnetic parameters were found in simple manganese ferrite, which has the largest crystallite size.