Influence of rare-earth additives (La, Sm and Dy) on the microstructure and dielectric properties of doped BaTiO3 ceramics

• Published in: Science of sintering Vol. 42; no. 1; pp. 69 - 79
• Main Authors: Paunovic, V, Zivkovic, L, Mitic, V
• Format: Journal Article
• Language: English
• Published: International Institute for the Science of Sintering, Beograd 01.01.2010
• Subjects: Barium titanates; batio3 doped ceramics; Core-shell structure; dielectric properties; Dysprosium; Grains; Manganese; Microstructure; microstructures; Rare earth metals; Sintering
• ISSN: 0350-820X; 1820-7413
• DOI: 10.2298/SOS1001069P

A series of La/Mn, Sm/Mn and Dy/Mn codoped BaTiO3 samples were prepared by the conventional solid state method with dopant concentrations ranging from 0.1 to 2.0 at%. The specimens were sintered at 1320 C and 1350 C in an air atmosphere for 2 h. The low doped samples demonstrated a mainly uniform and homogeneous microstructure with average grain sizes ranging from 0.3 to 5.0 micron. The appearance of secondary abnormal grains in the fine grain matrix and core-shell structure was observed in highly doped La/BaTiO3 and Dy/BaTiO3 sintered at 1350 C. The low doped samples, sintered at 1350 C, showed 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 and a critical exponent, gamma, were calculated. The obtained values of gamma pointed out the diffuse phase transformation in heavily doped BaTiO3 samples.