Properties of perovskites La1-xCdxMnO3

The La1-xCdxMnO3 (x = 0.1, 0.2, 0.3) perovskites have been prepared by solid reaction technology with sintering temperature of 1050 degrees C. The samples are of single phase with rhombohedral structure of R-3c symmetry. The field-cooled (FC) and zero-field-cooled (ZFC) thermomagnetic measurements at low field indicate the spin glass-like state (or cluster glass) at low temperatures and a sharp change of magnetization around the phase-transition point of composition La0.7Cd0.3MnO3. This sample exhibits large value for maximum magnetic-entropy change vertical bar Delta S-m vertical bar(max) of 2.88 J/kg K in the field of 13.5 kOe and reveals giant magnetocaloric effect. This value for vertical bar Delta S-m vertical bar(max) is larger than that of La0.7Sr0.3MnO3 and La0.7Pb0.3MnO3 perovskites. The resistance measurements show that the conductivity of La1-xCdxMnO3 perovskites is metallic at low temperatures and semiconducting at high temperatures but the metal-semiconductor transition temperatures are not coinciding with paramagnetic-ferromagnetic transition ones. The results can not be explained by using double-exchange (DE) model only. In addition to the DE Jahn-Teller lattice distortion plays an important role. (c) 2004 Elsevier B.V. All rights reserved.