Delayed thermal depolarization of Bi0.5Na0.5TiO3-BaTiO3 by doping acceptor Zn2+ with large ionic polarizability

Abstract

In this paper, (Bi0.5Na0.5)0.94Ba0.06Ti1-xZnxO3 ceramics (0 ≤ x ≤ 0.06) were prepared by the solid oxide reaction route. The doping of Zn2+ into Bi0.5Na0.5TiO3-6BaTiO3 delays the crossover from nonergodic to ergodic states, and the thermal depolarization temperature Td is delayed from 85 °C for pure samples to 120 °C for samples doped by 6% Zn2+, as confirmed by temperature-dependent dielectric and ferroelectric measurements. It suggests that the variation of the Td could be ascribed to the reformation of the long-range ferroelectric order due to the large ionic polarizability of Zn2+. The high ionic polarizability of Zn2+ can result in a large dipole moment of BO6 octahedra, thus strengthening the coherence of neighboring dipoles and suppressing the ferroelectric–relaxor transition. These results improve our understanding on the thermal depolarization of Bi0.5Na0.5TiO3-based ferroelectrics.

Thermal depolarization and electromechanical hardening in Zn2+‐doped Na1/2Bi1/2TiO3‐BaTiO3

“…For NBT6BT-0.5, T F-R increases by 40 o C. In the prior work on Zn 2+ -doping (15), the change in T F-R is the same as reported here except for the difference in the doping concentration, which can be attributed to the sensitivity of NBT to the Na + and Bi 3+ concentration, since they are volatile.…”

“…However, the effects of Zn 2+ substitution on electromechanical hardening was not reported. Until now, this report (15) provides the highest increase in T F-R for doped NBT100yBT.…”

“…Several strategies like doping (13)(14)(15), grain-size refinement (16), formation of composites (17) and quenching (18,19) have been adopted to Accepted Article enhance the thermal stability and/or the mechanical quality factor. Although several chemical modifications of NBT100yBT have been reported in the literature (15,(20)(21)(22)(23)(24), the most promising approaches have been composite formation (17) and quenching (18). In the case of the NBT6BT composites with ZnO inclusions, it was demonstrated that T F-R can be increased up to 40 o C (25) with the maximum in Q m of 420 (11).…”

Spontaneous ferroelectric order in lead-free relaxor Na1/2Bi1/2TiVenkataraman1, Hinterstein2, Lee3 et al. 2020Phys. Rev. B15000View full textAdd to dashboardCite

“…4(d)], points to the role of Zn diffusion in the matrix NBT9BT phase. Since prior reports claim that Zn diffusion [56] or substitution [24] can also stabilize a ferroelectric phase, it is likely that the ferroelectric seeds that are stabilized using stress or chemical modification, can act as new nucleation sites for the expanse of the ferroelectric domains. Note that both the residual stress and diffusion of zinc are likely to be colocated at the NBT9BT/ZnO interface and, therefore, it is not trivial to distinguish these effects.…”

“…In the former, the ferroelectric order develops due to the ordering of the B-site cations, while in the latter, it is proposed that the presence of Pb vacancies limits the occurrence of ferroelectric order. In recent years, increase in the ferroelectric→relaxor (FE→ RE) transformation temperature (T F-R ) is reported for (1 − x)Na 1/2 Bi 1/2 TiO 3 -xBaTiO 3 (denoted as NBTzBT; z = 100x) based materials and attributed to the stabilization of ferroelectric order [22][23][24][25]. NBTzBT exhibits a morphotrophic phase boundary (MPB) between 5 and 12 mole % BT [20,[26][27][28].…”