Dielectric properties of La/Mn codoped barium titanate ceramics

La/Mn codoped BaTiO 3 ceramics with different La 2 O 3 content, ranging from 0.3 to 1.0 at% La, together with undoped BaTiO 3 ,were investigated regarding their microstructure and dielectric properties. The content of MnO 2 kept constant at 0.01 at% Mn in all investigated samples. La/Mn codoped and undoped BaTiO 3 were obtained by a modified Pechini method and sintered in air at 1300 0 C for two hours. The homogeneous and completely fine-grained microstructure with average grain size from 0.3 to 1mm was observed in samples doped with 0.3 at% La. In high doped samples, apart from the fine grained matrix, the appearance of local area with secondary abnormal grains was observed. The dielectric permittivity and dissipation factor were investigated as a function of frequency and temperature. Dielectric permittivity of doped BaTiO 3 was in the range of 3945 to 12846 and decreases with increase of additive content. The highest value of dielectric constant at room temperature (e r = 12846) and the greatest change at Curie temperature (e r = 17738) were measured in 0.3at% La doped samples. Dissipation factor was range from 0.07 to 0.62 for all investigated samples. The Curie constant (C) and Curie-Weiss temperature (T 0 ) together with critical exponent of nonlinearity (g) were calculated using a Curie-Weiss and modified Curie-Weiss law. The Curie constant increase with increasing dopant content and the highest values were measured in 1.0 La doped samples. The obtained values of g is in the range from 1.04 to 1.53 and pointed out the sharp phase transformation from ferroelectric to paraelectric phase at Curie temperature.