Syntheses and magnetic properties of La_1-xSr_xMnO_y (0.5 ≤ x ≤ 1.0) perovskite

La_1-xSr_xMnO_y with 0.0 ≤; x ≤ 0.6, which reveals very interesting physical properties such as ferromagnetism and metallic resistivity, can easily be synthesized by the conventional solid state reaction. In the case of the composition of x > 0.6, they cannot be synthesized by the normal synthesis but by the two-stage solid state reaction, which at first makes the oxygendeficient state at high temperature and then inserts oxygen by O₂ annealing at low temperature. Nevertheless all of obtained compound is single phase cubic perovskite structure, ferromagnetism and metallic property observed in the composition range 0.175 ≤ x ≤ 0.6 are not revealed, cause of drastic change between 0.50 ≤ x ≤ 0.60.