Relaxor effect on electric field induced large strain in (1−x)(Bi0.5Na0.5)TiO3–xBaTiO3 lead-free piezoceramics

Large E-field induced strain and polar evolution in lead-free Zr-doped 92.5%(Bi0.5Na0.5)TiO3–7.5%BaTiO3 ceramics

“…23 However, many works proposed the coexistence of rhombohedral and tetragonal phases in BNT-based polycrystalline ceramics and single crystals near the MPB. 14,22,23,45 The mixed phase of rhombohedral and tetragonal structures can average out various distortions of unit cells and thus increase the crystallographic structure toward pseudo-cubic symmetry. 46 The Zr-modified BNT7.5BT can be regarded as a major pseudocubic structure with a slight distortion from cubic cell.…”

“…19,21 Therefore, the large strain response in these BNT-based materials could be attributed to E-field induced phase transformation of polar nanostructures, 20 which allow the existences of lower energy barriers for dipole reorientation/switching under an external E field. 22 It has been known that the free energy between the P4bm polar nanoregions and P4mm ferroelectric phase is very competitive, which can make transition from the polar nanoregion to long-rangeordered ferroelectric phase that takes place easily in the presence of a relatively high field for the BNT-based materials. [22][23][24] Relaxor ferroelectric materials display electrostrictive and Efield induced linear strain features.…”

“…22 It has been known that the free energy between the P4bm polar nanoregions and P4mm ferroelectric phase is very competitive, which can make transition from the polar nanoregion to long-rangeordered ferroelectric phase that takes place easily in the presence of a relatively high field for the BNT-based materials. [22][23][24] Relaxor ferroelectric materials display electrostrictive and Efield induced linear strain features. Electrostrictors have special advantage for piezoelectrics, because there is negligible hysteresis in E-field induced strain (S-E) cycle, which is important for precision position controller.…”

Structural stability and depolarization of manganese-doped (Bi0.5Na0.5)1−xBaxTiO3 relaxor ferroelectrics

“…[16][17][18] The large piezoelectricity and strain are associated with an E-field-induced transformation of the polar nanostructures, 19 which allows lower energy barriers for dipole reorientation. 7 The free energies of the P4bm polar nanoregions and P4mm ferroelectric phase are similar, so the transition from the PNRs to the long-range-ordered ferroelectric phase can occur under an E field. 20,21 Local monoclinic nanotwins in an overall rhombohedral symmetry have been proposed in BN100xBT compounds to act as the bridging phase for polarization rotation between the rhombohedral and tetragonal structures.…”

“…4,5 BNT-based materials have been developed for large piezoelectric and strain responses. [6][7][8][9][10][11][12][13] The most studied BNTbased compounds include BNT-BaTiO 3 or (Bi 0.5 Na 0.5 ) 1Àx Ba x TiO 3 , 6-8 BNT-(Bi 0.5 K 0.5 )TiO 3 , 9 BNT-KNbO 3 , 10 BNTBiFeO 3 , 11 BNT-SrTiO 3 , 12 and BNT-BT-(K 0.5 Na 0.5 )NbO 3 . 13 (Bi 0.5 Na 0.5 ) 1Àx Ba x TiO 3 (abbreviated as BN100xBT) exhibits a morphotropic phase boundary (MPB) between the R and T structures near x ¼ 0.06 $ 0.07, 14,15 accompanied by polar nanoregions (PNRs) and large E-field-induced piezoelectricity.…”