Enhanced Tunability Properties of Pure (Ba,Sr)TiO3 Lead free Ferroelectric by Polar Nano-region Contributions

Abstract In the present work, a series compositions of (Ba1-xSrx)TiO3 (0≤x≤0.4) lead-free ferroelectric (BST) were successfully prepared by sol-gel method. The effects of Sr2+ on the optical properties, crystal structure and morphology of BaTiO3 were systematically investigated. Compositions with x<0.4 exhibit single phase tetragonal perovskite at room temperature, while a cubic structure of BST has been detected in the ceramic with x=0.4. Phase transition temperature was shifted toward lower temperature by increasing Sr-doping. Moreover, detailed tunability analysis for the present ceramics confirmed an enhancement by Sr-addition and the maximum values were observed at Sr=0.2. The enhancement back to present multiple components contribute to the dc-field induced dielectric constant, where at low electric fields the Langevin theory indicate present polar nano-region (PNR) contributions into tunability data, however domain switching contributions at high electric field was described by Johnson equation. Ferroelectric properties appraised by P-E loop and positive up negative down (PUND) methods have been introduced. The results shown the remnant polarization appraised by PUND method is much lower than polarization estimated by P-E loop indicate the difference values of Pr is mostly owing to leakage current contribution in P-E method.