We have investigated the influence of oxygen vacancies on electronic transport and magnetic property of polycrystalline bulk La0.5Ca0.5MnO3 （LCMO）. With increasing content of oxygen vacancy, its resistivity at high temperature increases monotonically and follows the adiabatic small-polaron model. The resistivity at low temperature first deereases, then increases, and has the behavior of dR/dT>0 evidently. The resistivity at low temperature becomes insulating at last. Increasing the oxygen vacancies depresses the appearance of antiferromagnetic phase. As a result, antiferromagnetic transition does not occurs in oxygen-deficient LCMO samples. On more increasc of oxygen vacancies, ferromagnetic phase will eventually be suppressed.
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