Pr1-xCaxMnO3 system in the crossover region between different kinds of magnetic ordering

The magnetic and transport properties of the Pr1-xCaxMnO3 system were studied in the characteristic points of the phase diagram corresponding to the ferromagnetic insulating (FI) and charge-ordered anti ferromagnetic states. The magnetization M and resistivity p of the ceramic samples with x = 0.2, 0.25, 0.27, 0.29, 0.30, and 0.33 were measured at temperatures T = 4-300K and applied magnetic fields H up to 6T. The isotope substitution O-16 --> O-18 was performed for the samples with x = 0.2, 0.25, 0.30. Special attention was paid to the possible manifestations of the phase separation in the FI state. (C) 2002 Elsevier Science B.V. All rights reserved.