In this article, ytterbium and erbium oxides are used as doping materials for barium titanate (BaTiO 3 ) materials. The amphoteric behavior of these rare-earth ions leads to the increase of dielectric permittivity and decrease of dielectric losses. BaTiO 3 ceramics doped with 0.01-0.5 wt% of Yb 2 O 3 and Er 2 O 3 were prepared by conventional solid-state procedure and sintered at 13201C for 4 h. In BaTiO 3 doped with a low content of rareearth ions (0.01 wt%) the grain size ranged between 10 and 25 lm. With the higher dopant concentration of 0.5 wt%, the abnormal grain growth is inhibited and the grain size ranged between 2 and 10 lm. The measurements of capacitance and dielectric losses as a function of frequency and temperature have been carried out in order to correlate the microstructure and dielectric properties of doped BaTiO 3 ceramics. The temperature dependence of the dielectric constant as a function of dopant amount has been investigated.

No abstract

No abstract

No abstract

A series of La/Mn, Sm/Mn and Dy/Mn codoped BaTiO3 samples were prepared by the conventional solid state procedure with dopant concentrations ranging from 0.1 up to 2.0 at%. The specimens were sintered at 1320°C and 1350°C in an air atmosphere for two hours. The low doped samples demonstrated a mainly uniform and homogeneous microstructure with average grain sizes ranging from 0.3 μm to 5.0 μm. The appearance of secondary abnormal grains in the fine grain matrix and core-shell structure were observed in highly doped La/BaTiO3 and Dy/BaTiO3 sintered at 1350°C. The low doped samples, sintered at 1350°C, display a high value of dielectric permittivity at room temperature, 6800 for Sm/BaTiO3, 5900 for Dy/BaTiO3 and 3100 for La/BaTiO3. A nearly flat permittivity-response was obtained in specimens with 2.0 at% additive content. Using a modified Curie-Weiss law the Curie-like constant C⁄ and a critical exponent γ were calculated. The obtained values of γ pointed out the diffuse phase transformation in heavily doped BaTiO3 samples