Abstract
Both Y-La-Bi substituted and non-substituted Sr-hexaferrites (SrM) were synthesized by sol-gel auto combustion technique and the influences of Y, La and Bi ions on ac/dc conductivities, dielectric constant/loss properties as well as complex dielectric modulus were investigated extensively for a variety of substitutions. It was observed that ac conductivity of SrM increases slightly with increasing Y3+ La-3, and Bi3+ substitutions at first, and then decreases with its further increments. Furthermore, ac conductivity increased with increasing frequency which could be regarded as an origin indication of both electronic and polaron hopping mechanism. It is also worthy to note that the activation energy, which is an indication of both mechanisms depicted in the Arrhenius plot, is increased as the enhanced contributions of substitutions in SrM with the illustration of a better stability and tunability of electrical bonds among substituted ions and ferrous and ferric ions. The dielectric constant, dielectric loss and dielectric modulus represent a very interesting tunability and optimised consequences regarding to the variation of frequencies, temperatures and substitutions of SrM. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.