Composition Crystal structure Energy dispersive spectroscopy Entropy Magnetization Microstructure Phase transitions Scanning electron microscopy Spin glass Thermal effects Double exchange (DE) models Magnetic oxides Magnetocaloric effects Spin glass behavior Perovskite
Issue Date:
2005
Publisher:
Journal of Magnetism and Magnetic Materials
Citation:
Volume 290-291 PART 1, Page 690-693
Abstract:
The La1-xCdxMnO3 (x=0.1, 0.2, 0.3) perovskites have been prepared by solid reaction technology
with sintering temperature of 1050 ?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 La0.7Cd 0.3MnO3. This sample exhibits large value for
maximum magnetic-entropy change |??Sm|max of 2.88 J/kg K in the field of 13.5 kOe and reveals giant
magnetocaloric effect. This value for |??Sm|max is larger than that of La 0.7Sr0.3MnO3 and La0.7Pb 0.3
MnO3 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. ?? 2004 Elsevier B.V. All rights reserved
