Structural and magnetic size effects in nanodisperse Zn$_x$Fe$_{3-x}$O$_4$ ferrite systems

The technology of producing highly disperse ferrite Zn$_x$Fe$_{3-x}$O$_4$ ($x$ = 0–0.5) powders has provided a high biochemical purity, a specified dispersion, and a required level of functional magnetic parameters. The average particle sizes indicating their belonging to the lower limit of the nanometer range have been determined by X-ray diffraction and electron microscopy. Based on the X-ray diffraction patterns, the crystal lattice parameters have been determined as functions of the zinc ion concentration. The magnetic measurements performed at 300 K have revealed an increase in the magnetization due to the substitution, as well as the existence of the size effect, namely, the superparamagnetic state of powder particles.