Abstract: Pure BaTiO₃ ceramics and Pr, Mn-doped BaTiO₃ ceramics were prepared by a sol-gel method. The pure BaTiO₃ ceramics were modified by the penetration of Pr and Mn in gaseous state, their structure and electrical properties were studied. The results show that the resisitivity of Pr-doped BaTiO₃ ceramics is decreased to 1.01×10⁵Ω·m, the resisitivity of Mn-doped BaTiO₃ ceramics is increased to 1.50×10¹³Ω·m, while both Pr and Mn penetration can decrease the resisitivity of BaTiO₃ ceramics evidently, which is 1.08×10³Ω·m and 1.29×10⁵Ω·m, respectively . The Pr-Mn penetrated BaTiO₃ ceramics show a distinct NTC effect. The XRD results show that the perovskite structure of Pr or Mn doped BaTiO₃ ceramics does not change obviously, but there are new peaks of BaMn_0.12Al_1.88O₄ and Al₈Mn₄Pr in Pr-Mn penetrated BaTiO₃ ceramics. The XPS results show that Pr, Mn and C element are penetrated into BaTiO₃ ceramics, leading to the binding energy of modified BaTiO₃ ceramics increase and their stability improve. The SEM results show that Pr and Mn penetration can improve the surface state of BaTiO3 ceramics, the grains become finer and grow more integrally than pure BaTiO₃ ceramics, the porosity are decreased visibly.

Key words: BaTiO₃, rare earth, gaseous penetration, NTC effect