Crystal structure and magnetic properties of ferrites ofSr<sub>1-x</sub>Pr<sub>x</sub>Fe<sub>12-x</sub>Co<sub>x</sub>O<sub>19</sub>, (Sr<sub>0,85</sub>Ca<sub>0,15</sub>)<sub>1-x</sub>Pr<sub>x</sub>Fe<sub>12-x</sub>Co<sub>x</sub>O<sub>19 </sub> systems
Crystal structure of Sr 1- x Pr x Fe 12- x Co x O 19, (Sr 0.85Ca 0.15) 1- x Pr x Fe 12- x Co x O 19  ( x ≤0.5) ferrites is investigated. Dependence of a and c lattice parameters on x was determine. Hysteresis curve is obtained at the temperatures 6 and 300 K at the magnetic fields up to 14 T. Dependence of saturation magnetization and coercive force on x at 6 and 300 K was investigated. It is shown that ferrites Sr 1- x Pr x Fe 12- x Co x O 19, (Sr 0.85Ca 0.15) 1- x Pr x Fe 12- x Co x O 19  (0.1≤ x ≤0.2) can be used for making permanent magnets with better characteristics than SrFe 12O 19  and Sr 0.85Ca 0.15Fe 12O 19 .