Effect of V addition on magnetic, transport, and microstructural properties of La 0.7 Sr 0.3 MnO 3

The microstructural, magnetic, and magnetotransport properties of polycrystalline samples with nominal composition of La 0.7 Sr 0.3 Mn 1– x V x O 3 (0 ≤ x ≤ 0.25) sintered in air have been investigated. It is found that V could not substitute for Mn to form La 0.7 Sr 0.3 Mn 1– x V x O 3 . The samples contain several phases such as (La, Sr)Mn 1– δ O 3 , LaSr 3 V 3 O 12 , Mn 3 O 4 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)Mn 1– δ O 3 phase. The Curie temperature T C 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)