Structural and electrical characteristics of rare-earth modified bismuth layer structured compounds

Polycrystalline ceramics Bi3ZrVO9, Bi2LaZrVO9, Bi2NdZrVO9, and Bi2SmZrVO9 of the Aurivillius family were prepared through the mixed oxide reaction method. The grain size in the samples decreases with decreasing bond dissociation energy of the elements with oxygen. The grain boundary contribution in the samples activates at temperature >= 350 degrees C, resulting in a very large dielectric constant albeit at a lower frequency. The complex dielectric plot confirms the Cole-Cole model of relaxation in the compounds. All these samples exhibit ferroelectric nature. The substitution of the rare earth elements seems to substantially decrease the oxygen vacancy and thus the loss-tangent. The contribution of the Debye part and the DC conductivity to the loss tangent is resolved. The calculated ionization energy for both the relaxation and the conduction processes indicate the involvement of doubly ionized oxygen vacancy. The correlated barrier hopping (CBH) model seems to be the dominant conduction mechanism in the samples. (C) 2021 Elsevier B.V. All rights reserved.