Effect of ionic ordering on magnetic properties of Ln/sub 1-x/A/sub x/MnO/sub 3-/spl delta// (Ln = La, Pr, Nd; A = Ca, Ba; x = 0.30, 0.50) anion-deficit perovskite manganites

Summary form only given. Magnetization, electrical resistivity and magnetoresistance of Ln/sub 0.50/Ba/sub 0.50/MnO/sub 3-/spl delta// (Ln = Pr, Nd) manganites with perovskite structure have been investigated as a function of the oxygen content. It was found that the stoichiometric samples (prepared in air) are ferromagnets and show T/sub C/ /spl ap/ 110 K (first order phase transition) whereas the reduced ones (annealed in evacuated silica tubes) with /spl delta/ = 0.50 are weak ferromagnets and show the magnetic ordering temperature /spl sim/ 140 K. X-ray investigations have detected the cubic and tetragonal unit cells for the stoichiometric and reduced samples, respectively. Crystal structure parameters, magnetic and electrical properties of the La/sub 1-x/Ca/sub x/MnO/sub 3-/spl delta// (x = 0.30, 0.50; 0/spl les//spl delta//spl les/0.50) reduced manganites have also been experimentally established.