The Effect of Contact Non-equilibrium Plasma on Structural and Magnetic Properties of Mn(Х)Fe(3 − X)О(4) Spinels

Nano-sized manganese ferrites Mn(х)Fe(3 − х)О(4) (х = 0–1.3) were prepared using contact non-equilibrium plasma (CNP) in two different pH (11.5 and 12.5). The influence of synthesis conditions (e.g., cation ratio and initial pH) on phase composition, crystallite size, and magnetic properties were investigated employing X-ray diffraction (XRD), differential thermal analysis (DTA), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and magnetic measurement techniques. The formation of monodispersed faceted ferrite particles at х = 0–0.8 was shown. The FTIR spectra revealed reflection in region 1200–1700 cm(−1) caused by the presence of water adsorbed on the surface of Fe(3 − x)Mn(x)O(4) micro-granules or embedded into their crystal lattice. The most sensitivity of reflection spectra to the composition changes takes place within a 400–1200 cm(−1) range, typical to the stretching vibrations of Fe(Mn)–O (up to 700 cm(−1) ), Fe(Mn)–OH, and Fe(Mn)–OH(2) bonds (over 700 cm(−1)). The XRD results showed that the nanocrystalline Mn(х)Fe(3 − х)О(4) (0 < x < 1.0) had cubic spinel crystal structure with average crystallite size 48–49 A. The decrease of crystalline size with the x increase was also observed.