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Polycrystalline La0.67Ba0.33MnO3 bulk samples were annealed in flowing 95％ Ar:5％H2 (AH) mixed gas at 973 K for different time respectively.The influence of the annealing time on the current-voltage properties was systematically investigated.Linear current-voltage characteristics were observed in the as-prepared and the 10 h annealed samples,and nonlinear current-voltage characteristics was found in the 100 h antnealed sample.At the same time,segregation of impurity phase and micro-cracks were found on the surfaces of the 100 h annealed samples,which was testified to be Ba ion impurity.Analysis showed that tie changes of electronic properties were caused by barium ion impurities and micro-cracks in the 100 h annealed sample.