Effect of V addition on magnetic, transport, and microstructural properties of La_0.7Sr_0.3MnO₃

Abstract

The microstructural, magnetic, and magnetotransport properties of polycrystalline samples with nominal composition of La0.7Sr0.3Mn1–x Vx O3 (0 ≤ x ≤ 0.25) sintered in air have been investigated. It is found that V could not substitute for Mn to form La0.7Sr0.3Mn1–x Vx O3. The samples contain several phases such as (La, Sr)Mn1–δ O3, LaSr3V3O12, Mn3O4 etc. and constitute multi‐phase composites. The Sr–V‐rich phase form a liquid phase during sintering process and the sintering be long to liquid‐phase sintering, which may effectively promote grain growth of (La, Sr)Mn1–δ O3 phase. The Curie temperature TC and saturation magnetization of the composites decrease with increasing the V content x. 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. The MR ratio at a low field of 2 kOe reaches 25% for the x = 0.15 sample at 84 K. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)