Deterioration behavior analysis of dysprosium and thulium co-doped barium titanate ceramics for multilayer ceramic capacitors

An accelerated testing method for barium titanate (BaTiO3) dielectrics was proposed to elucidate deterioration behavior of dielectric constant based on the life-temperature relation. The accelerated degradation test (ADT) which was designed using various temperature ranges below and above Curie temperature (Tc) was focused on the optimized composition of dysprosium (Dy) and thulium (Tm) co-doped BaTiO3. The statistical analysis of the failure time data was performed to determine the optimum distribution as a goodness-of-fitness test. A scale parameter (η) and activation energy (Eα) were calculated in order to predict the life time of the co-doped BaTiO3, and there was difference between the expected life times according to the acceleration temperature rating of the ADT. The difference of deterioration mechanism around Tc could be deduced from the change of lattice parameter and polarization behavior. The drastic decrease of tetragonality and ferroelectric property caused by the phase transition of the co-doped BaTiO3 was verified in the temperature above Tc. Accordingly, the acceleration factor over Tc should be considered as reliability study of the BaTiO3 dielectrics for multilayer ceramic capacitors (MLCCs).