Crossover from ferroelectric to relaxor and cluster glass in BaTi1−xZrxO3 (x = 0.25–0.35) studied by non-linear permittivity

The electric susceptibilities χ1, χ2, and χ3 of BaTi1−xZrxO3 ceramics with 0.25 ≤ x ≤ 0.35 are measured at 90 ≤ T ≤ 350 K and 37 ≤ f ≤ 106 Hz. Crossover from ferroelectric (x = 0.25) to relaxor behavior (x = 0.35) via coexistence of both (x = 0.30) is indicated by increasing polydispersivity and suppression of χ2 intensity and negative χ3 tails. The relaxor properties are due to weak random fields acting on dipolar Ti4+ clusters in non-polar Zr4+ environment. Frustrated interaction between blocked polar nanoregions yields a cluster glass ground state for x = 0.35.