Relaxor behavior and tunable property of lead-free Li+-doped Ba0.9Ca0.1Zr0.2Ti0.8O3 ceramics

Li+ doped lead-free Ba0.9Ca0.1Zr0.2Ti0.8O3 (abbreviated as BCZTL) ceramics were prepared through solid-state reaction method. Effects of Li+ on the formation of oxygen vacancies, change of lattice parameters and grain sizes were investigated. The disordered distribution of Li+ ions on B sites of BCZTL were found to give rise to the emergence of local random fields and facilitate the appearence of polar nanoregions (PNRs), which led to the relaxor behavior observed in dielectric measurements. The physical mechanisms for the influences of Li+ substitution and sintered temperature on the variation of PNRs, relaxor behavior and tunability were also proposed. Compared with other sintered temperatures, the 1300 °C sintered BCZTL sample exhibited relatively lower degree of relaxor behavior (γ = 1.89) and higher tunability (k = 56%) owning to the smaller PNRs size.