Ferroelectric‐quasiferroelectric‐ergodic relaxor transition and multifunctional electrical properties in Bi_0.5Na_0.5TiO₃‐based ceramics

Abstract

A-site substituted 0.88(Bi 0.5 Na 0.5 ) 1Àx (Li 0.5 Nd 0.5 ) x TiO 3 -0.12BaTiO 3 (BNTLNx-BT12) ceramics were synthesized using a conventional solid-state reaction route. The structural transformation and miscellaneous electrical properties were systematically investigated. The A-site modification induced two sequence transitions from ferroelectric tetragonal (T) to quasi-ferroelectric pseudocubic (PC) phase, followed closely by the second transition from non-ergodic to ergodic relaxor (NR-ER), and finally to dynamic polar nanoregions (PNRs). The significant enhancement in piezoelectric activity, strain response, broad plateau-like maximum dielectric permittivity over a large temperature range and energy-storage level at different compositions may be attributed to the compositionally-induced T-PC to NR-ER transition and the alignment of dynamically-fluctuating PNRs, respectively. The evolution of multifunctional electrical properties, associated with the variations in structure/microstructure, might provide a new insight to investigate the underlying mechanism of structure-electrical properties relationship in ferroelectric solid solutions. K E Y W O R D Sdielectric properties, ferroelectricity, phase transitions, piezoelectricity

Large strain under low driving field in lead‐free relaxor/ferroelectric composite ceramics

“…Much efforts has focused on decreasing the electric field strength required to trigger the phase transition. Such as the method of exploring a new materials inherently possessing low driving fields, texturing technology, and relaxor/ferroelectric composite method have been adopted . Among them the most powerful approach is to develop relaxor/ferroelectric (RE/FE) ceramic composite structures comprised of giant strain materials (matrix) and a FE or nonergodic relaxor (seed), which have been implemented to decrease the required external poling field.…”

Dielectric behaviors and relaxor characteristics in Bi0.5Na0.5TiO3-BaTiO3 ceramics

“…The solid solution of Bi 0:5 Na 0:5 TiO 3 -BaTiO 3 (BNT-BT) is one of the most extensively investigated lead-free candidates due to its excellent piezo-responses and varieties structures. [1][2][3][4][5][6][7][8][9][10][11][12] BNT has a distorted perovskite ABO 3 structure and exhibits structural disorders on the nanoscale because of the mixed site occupancy of Na þ1 and Bi þ3 ions at A-site. [13][14][15][16][17][18][19][20] The aliovalent partial order or disorder of cations at A-site was understood to be the reason behind the anomalous properties and the intriguing structures.…”

“…The local structural heterogeneities and the relative stability of its R3c and Cc phases make the BNT-based ceramics as multi-functional materials with good small signal piezoelectric response, high strain activity and enhanced energy storage performance. 10,[30][31][32][33][34][35] Especially, BNT-based ceramics were observed to have several dielectric anomalies distinguished from canonical relaxors. [36][37][38][39] Simultaneously, the peculiar ferroelectric or relaxor properties depend on its mechanical or thermal treatment.…”

“…Importantly, the appearances of relaxor ferroelectrics (REs), nonergodic relaxor (NR), ergodic relaxor (ER), anti-ferroelectrics (AFEs) and composition/field/ temperature-induced transitions among the disordered-ordered ferroelectric state, along with adequate dielectric, electromechanical and macroscopic strain in BNT-based ceramics, have attracted significant amount of attention. 10,29 The evolution of disordered-ordered ferroelectric state induced by composition/field/temperature variations features different macroscopic properties, thus, giving rise to a complicated evolution of the dielectric properties. Consequently, dielectric spectroscopy, such as frequency-dependent peak in the temperature(TÞ-dependent dielectric susceptibility and frequency-dispersive dielectric maxima, is particularly advantageous for characterizing RE phase transition due to the absence of macroscopic phase (symmetry) change at the transition.…”

High‐energy storage and temperature stable dielectrics properties of lead‐free BiScO 3 –BaTiO 3 – x (Bi 0.5 Na 0.5 )TiO 3 ceramics

“…The BNT–BT solid solutions obtain excellent electric properties around the morphotropic phase boundary. On this foundation, further studies centring on elevating energy storage capabilities of BNT–BT binary system have been implemented through incorporating new composition (K 0.5 Na 0.5 NbO 3 , calcium zirconate, strontium titanate) [7–9], single ion (La 3+ , Sn 4+ ) [10, 11], double ions (La 3+ /Zr 4+ ) [12], and complex ions [(Al 1/2 Nb 1/2 ) 4+ , (Li 1/2 Nd 1/2 ) 2+ ] [13, 14].…”