Magnetic, transport and microstructural properties of polycrystalline samples with nominal composition of La0.7Ca0.3Mn1−xVxO3 (0⩽x⩽0.2)

Polycrystalline samples with nominal composition of La0.7Ca0.3Mn1−xVxO3 (0⩽x⩽0.2) sintered in air were investigated by ac susceptibility, dc magnetization, magnetoresistance (MR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential thermal analysis (DTA) measurements. It is found that V could not substitute for Mn to form La0.7Ca0.3Mn1−xVxO3 phase when the samples are sintered in air. The obtained samples contain several phases such as (La, Ca)Mn1−δO3, LaCa3V3O12, Mn3O4 phases, etc. and constitute multi-phase composites. The Curie temperature TC and spontaneous magnetization of the composites decrease, and the resistance of the composites increases as the V content increases. The addition of V may effectively improve the low-field MR response at low temperatures due to the variation in the microstructure of the composites.