Structural transition and giant strain induced by A- and B-site concurrent donor doping in Bi-0.5(Na0.84K0.16)(0.5)TiO3-SrTiO3 ceramics

摘要

Lead-free 0.96[Bi-0.5(Na0.84K0.16)(0.5)}(1-x)La-x(Ti1-yNby)O-3]-0.04SrTiO(3) (BNKLTN-ST, with x, y=0.00-0.030) ceramics were synthesised by conventional solid state reaction (CSSR) method. Results showed that A-and B-site concurrent donor doping into BNKT-ST ceramics induces a phase transition from coexistence of ferroelectric tetragonal and rhombohedral to a relaxor pseudocubic phase with a significant disruption of the long-range ferroelectric order. At an optimal composition (x, y=0.010), a giant field-induced strain of S=0.38% was achieved at an applied field of 5 kV/mm, with a corresponding normalized strain (S-max/E-max) of 760 pm/V. Besides this, at further low field of 4 kV/mm, the Smax/Emax value slightly decreased to 725 pm/V, which is still highest among those obtained in non-textured lead-free BNT-based ceramics at such a low field. (C) 2015 Elsevier B.V. All rights reserved.