New strategy for simultaneously achieving enhanced piezoelectricity and deferred Td in Bi0.5Na0.5TiO3-based relaxor ferroelectrics

Abstract

The inverse relationship between the piezoelectricity and depolarization temperature Td impedes the development of Bi0.5Na0.5TiO3 (BNT)-based ceramics. To realize the goal of enhancing the piezoelectricity together with a deferred Td, the intrinsic formation mechanism of Td should be well understood. In this work, considering the role A-site cations play in manipulating the relaxor behavior of BNT, Pb2+, Ba2+, Sr2+, and Ca2+ (with distinguished ferroelectricity and polarity) are selected to investigate the formation mechanism of Td. Td reflects the stability of polarizations, which could be manipulated through modifying the polarization field and local electric and strain fields. The introduction of Pb2+ and Ba2+ increases the long-range correlated ferroelectric P4 mm phase, which strengthens the polarization field and stabilizes polarizations, while the introduction of Sr2+ and Ca2+ increases the short-range correlated ferroelectric P4 bm phase and the non-ferroelectric phase, which weakens the polarization field and destabilizes polarizations. Domain structures captured by a piezoresponse force microscope corroborate the effect of Pb2+ and Ba2+ in stabilizing polarizations and Sr2+ and Ca2+ in destabilizing polarizations. Therefore, by introducing the ferroelectric component that exhibits a different local symmetry to the BNT-matrix and can also provide a strong polarization field, the simultaneously enhanced piezoelectricity together with a deferred Td could be realized, as validated in the designed BNT- xPbTiO3 system. This work investigates the formation mechanism of Td and guides the design of high-performance systems in BNT-based materials, benefiting the understanding of BNT-based relaxor ferroelectrics.

High energy storage density achieved in BNT‐based ferroelectric translucent ceramics under low electric fields

“…The samples exhibit strong frequency dispersion near T s and T m , which is related to the diffusion phase transition of the R 3 c phase and the evolution of PNRs in the P 4 bm phase 42,46 . After the introduction of BZT, ε r significantly increases, which can be explained by the fact that Ba 2+ ions can enhance ε r of the sample 26 . Subsequently, the decrease in ε r caused by higher concentrations of BZT doping is primarily attributed to the increased compositional disorder of A‐site (Bi 3+ , Na + , Ba 2+ and Er 3+ ) and B‐site (Ti 4+ and Zr 4+ ), leading to an increase in PNRs and subsequent dilution effects, as well as the resulting complexity in the orientation of electric dipoles within the PNRs 47…”

“…42,46 After the introduction of BZT, ε r significantly increases, which can be explained by the fact that Ba 2+ ions can enhance ε r of the sample. 26 Subsequently, the decrease in ε r caused by higher concentrations of BZT doping is primarily attributed to the increased compositional disorder of A-site (Bi 3+ , Na + , Ba 2+ and Er 3+ ) and B-site (Ti 4+ and Zr 4+ ), leading to an increase in PNRs and subsequent dilution effects, as well as the resulting complexity in the orientation of electric dipoles within the PNRs. 47 The ε r -T curves of ( 1 where ε m , T m , γ, and C are the maximum dielectric constant, the temperature corresponding to ε m , the dispersion coefficient, and the Curie-Weiss constant, respectively.…”

“…The difference in ionic radii between Zr 4+ and Ti 4+ contributes to hindering the long‐range ordering of ferroelectric domains, inducing PNRs 24,25 . The addition of Ba 2+ ions can enhance the polarization field and stabilize the polarization by increasing the long‐range correlated ferroelectric P 4 mm phase 26 . Therefore, in this work, BZT was selected to be added into BNT:0.6%Er 3+ , which is expected to realize superior energy storage properties and high transmittance.…”

Realization of the Giant Pyroelectric Response via Modulated Polar Structures

“…Due to the inherent structural and charge inhomogeneities in relaxor ferroelectrics, large-sized labyrinthine domains and nano-sized polar regions can usually be observed in non-ergodic relaxors and ergodic relaxors, respectively. [15,42] As illustrated in Figure 5a, the BNKLT sample exhibits small-sized labyrinthine domains attributed to introducing a partial ER phase within the NR phase. This is consistent with the above speculation, and the mixed NR+ER with reinforced polarization fluctuation should be responsible for the excellent RT pyroelectric coefficient (i.e., the BNKLT shows 1441 μCm −2 K −1 ).…”

Superior ferroelectric properties and enhanced depolarization temperature simultaneously achieved in BNT‐based ceramics

“…So far, researchers have made enormous efforts to improve the T d of BNT-based ceramics and adopted various strategies, such as composite design, defect engineering, quenching treatment, and so forth. [18][19][20][21][22][23][24][25] Typically, the strategy that forms 0-3 type composites between BNT-based ceramics and oxides (ZnO, Al 2 O 3 , and Zr 2 O 3 ) has been widely studied. In particular, the effects of ZnO on BNT-based ceramics have drawn much attention, and different mechanisms have been proposed.…”