Hydrothermal Synthesis and Magnetic Properties of Hexagonal Sr3Co2Fe24O41 Particles
Sr<sub>3</sub>Co<sub>2</sub>Fe<sub>24</sub>O<sub>41</sub> (SrZ) ferrites were synthesized by a hydrothermal method. The effects of atomic ratio of Fe/Sr (R<sub>Sr</sub>/Fe = x/8), hydrothermal reaction temperature (T<sub>H</sub>) and reaction time (tH), and the sintering temperature (T<sub>s</sub>) on the phase composition, microstructures, and magnetic properties of SrZ particles were investigated. In order to obtain a single Z-phase, x value in the initiative materials must be equal to 1.25. When x value is less than 1.25, α-Fe<sub>2</sub>O<sub>3</sub>, Sr<sub>3</sub>Fe<sub>2</sub>(OH)<sub>12</sub>, and unknown phase appear in the precursor powders, ultimately leading to impurity phases in the sintered specimens. When x value is >1.5, synthesis of Z-phase is difficult, since superfluous α-Fe<sub>2</sub>O<sub>3</sub> phase exists with M-phase and spinel phase in the precursor powders. Hexagonal SrZ sheets of ~2 μm wide and dozens of nanometers thick were obtained under optimized conditions. The magnetic measurements reveal that the easy magnetization axis of hexagonal Z-phase sheets at room temperature lies in the c plane.