Effects of La3+ doping ions on dielectric properties and formation of Schottky barriers at internal interfaces in a Ca2Cu2Ti4O12 composite system

Influences of La3+ substitution on the dielectric properties and formation of Schottky barriers at internal interfaces of a Ca2Cu2Ti4O12 (CaTiO3/CaCu3Ti4O12) composite system were investigated. It was found that electrostatic potential barrier height was greatly reduced by doping with La3+, leading to a large decrease in the total resistance of internal interfaces between grains. This observation was attributed to the creation of conduction electrons, which were possibly induced by electrical charge compensation of La3+ substitution into Ca2+ sites. Variations in the dielectric properties of La3+-doped CaTiO3/CaCu3Ti4O12 composite ceramics and nonlinear properties can be described based on the electrical responses at the internal interfaces between CaCu3Ti4O12-CaCu3Ti4O12 grains and CaTiO3-CaCu3Ti4O12 grains. Influence of possible charge compensation due to different levels of La3+ dopant on the formation of potential barriers was discussed.