Effect of V doping on electrical and magnetic properties of La0.71Ca0.29MnO3 polycrystalline ceramics

Abstract

A series of La0.71Ca0.29Mn1−xVxO3 (x = 0.00, 0.01, 0.03, 0.05, 0.10) ceramic samples were synthesized via sol–gel method. Structural, electric, and magnetic transport properties of samples were characterized. Results show that all samples have perovskite phases, and no impurity phases were detected. Slight doping with V on B sites does not change perovskite structure of samples, but the doping leads to lattice distortion through modifying Mn–O bond lengths and Mn–O–Mn bond angles. The cell volume increased, melting point decreased, and abnormal grain growth occurred as the content of V increased. Temperature dependence of sample resistivities (ρ–T) was tested using standard four-probe method. Results show that slight doping with V can effectively increase temperature coefficient of resistance (TCR) up to 37.04% K−1 (x = 0.01). However, this decreases metal–insulator transition temperature (TMI). Meanwhile, ρ–T dependence in magnetic field (1 T) shows that V substituting for Mn can significantly increase magnetoresistance of La0.71Ca0.29MnO3 near room temperature by ~ 78.3%, showing the promise of this material for use in magnetoresistive sensors, contactless magnetoresistive switches, and memories.