Relaxation dynamics and polydispersivity associated with defects and ferroelectric correlations in Ba doped EuTiO3

We presented detailed frequency and temperature dependent dielectric response in Eu1-xBaxTiO3 (0 l x l 0.5). Excluding grain boundary effects, four relaxation mechanisms have been observed. Relaxation dynamics were observed to arise due to hopping conduction associated with defects namely, oxygen vacancies, Eu3+ and Ti3+ ions. Dielectric relaxation analysis led to identification of Ti ions in two different environments with different relaxation rates in the overall EuTiO3 perovskite structure. Emergence of another relaxation mechanism associated with ferroelectric order as a consequence of formation of polar regions have also been observed for higher Ba concentrations. Addition of Ba led to the identification of relaxation dynamics associated with hopping conduction between Eu ions, Ti ions (in the regions with and without oxygen vacancies) and with the formation of ferroelectric polar regions. Furthermore, polydispersivity and relaxation times have been extracted within the frame work of modified Debye model. Relaxation times have been observed to increase with decrease in temperature while larger values of polydispersivity revealed wide distribution of relaxation times due to the presence of lattice parameter and energy barrier distributions.