The structural, magnetic and magnetotransport properties of La0.67Ca0.33MnO3: Ag-x (x = 0, 0.1, 0.2, 0.3 and 0.4) composites were investigated systematically. X-ray and EDX analysis indicated that Ag is not substituted into the main La0.67Ca0.33MnO3 phase and remains an additive to the second phase at the grain boundary. The Curie temperature first decreased from 269 K for x = 0 to 257 K for x = 0.1 and then remained nearly unchanged with increasing Ag content. For the x > 0.1 samples, a second transition temperature (T-M12) was observed in the resistance curves. At temperatures below 150 K, a significant enhancement in MR was observed while high temperature MR decreased with increasing Ag content. The maximum MR was observed to be 55% in the x = 0.4 sample at 10 K and a 6T magnetic field, this value is larger than that of pure La0.67Ca0.33MnO3 (53% at 265 K and 6 T). In addition, at low fields (H < 1T), a sharp increase in the MR was observed.
C1 [Gencer, H.; Pektas, M.; Kolat, V. S.; Izgi, T.; Atalay, S.] Inonu Univ, Dept Phys, Sci & Arts Fac, Malatya, Turkey.
[Babur, Y.] Harran Univ, Dept Phys, Sci & Arts Fac, Sanlyurfa, Turkey.