Separation of magnetic phases in La1-xCaxMnO3 manganites with. 0.6 ≤ x ≤ 0.9

The magnetic properties of La1-xCaxMnO3 solid solutions were studied in wide temperature and magnetic field ranges, T = 2-600 K and H less than or equal to 50 kOe. Semiconducting compositions with 0.6 < x < 0.9 exhibited an unusual temperature behavior of magnetization and susceptibility with well-defined Curie and Neel temperatures. The simultaneous manifestation of both ferromagnetic and antiferromagnetic properties is evidence of the coexistence of two collinear magnetic phases. The content of impurity ions was shown to have a strong influence on the T-C and T-N values, whereas the ratio between the ferro- and antiferromagnetic phase volumes heavily depended on thermal treatment conditions. The magnetic properties of the whole series of La1-xCaxMnO3 solid solutions can be explained in terms of the phase separation model. (C) 2001 MAIK "Nauka/Interperiodica".