Speaker
Dr
Xiaolan Liu
(Paul Scherrer Institute)
Description
Barium titanate (BaTiO3, BT) is the most extensively used perovskite dielectric ceramic material in the electronic industry. Its application includes multilayer ceramic capacitors (MLCs) traditionally made by covering BT with a layer of precious metal and firing. In order to reduce production costs, precious metal electrodes are replaced by base metal electrodes (BME) producing low-cost BME-MLCs and doped with trivalent rare-earth elements such as erbium (Er), holmium (Ho) and dysprosium (Dy) to improve the dielectric properties and lifetime of BME-MLCs. However, fundamental understanding of the role of the dopants is still lacking.
Using a combination of XAS spectroscopy and XRD (conventional/high-resolution), we studied site substitution of 1 at.% of Er3+, Ho3+ and Dy3+ in BT ceramics as functions of Ba/Ti stoichiometry and firing conditions (oxidising and reducing), as well as the effect of doping on the structure and microstructure of BT. Our first results suggest that the Ho3+ incorporated into the BaTiO3 lattice at the Ti4+ sites (Ho ) are compensated by ionized vacancies in the oxygen sublattice (V ); whereas Dy3+ can enter the BaTiO3 lattice at the Ba2+ as well as the Ti4+ sites. XRD results showed the doped BT exhibit complete solid solubility over all compositions with a tetragonal structure. The findings of this study can help better understand different amphoteric behaviours of the three dopants, which is of great importance for capacitor fabrication.
Primary author
Dr
Xiaolan Liu
(Paul Scherrer Institute)
Co-authors
Prof.
Christian Ludwig
(Paul Scherrer Institute)
Dr
Liu Testino
(Paul Scherrer Institute)
Dr
Maarten Nachtegaal
(Paul Scherrer Institute)
Prof.
Massimo Viviani
(National Research Council (Italy))
