Fe₃O₄ Segregation and Transport Properties of La_0.67Ca_0.33MnO₃

Effect of Fe₃O₄ segregation at grain boundaries on the electrical transport and magnetic properties of La_0.67Ca_0.33MnO₃ is investigated. The experimental results show that the Fe₃O₄ segregation not only shifts the paramagnetic--ferromagnetic transition temperature of La_0.67Ca_0.33MnO₃ to a lower temperature region but also induces a new transition in a lower temperature region. Meanwhile, the transition processes observed in both the resistivity and magnetization curves are obviously widened. Compared to pure La_0.67Ca_0.33MnO₃, we assume that the Fe₃O₄ segregation level at the grain boundaries can modify the electrical transport and magnetic properties of
La_0.67Ca_0.33MnO₃.