0.40% Bipolar Strain in Lead Free BNT–KNN System Modified with Li, Ta and Sb


Author to whom correspondence should be addressed. e-mails: ratnamalac@gmail.com and rmala@physics.iitd.ac.in


In this work we demonstrate a large electric field-induced bipolar strain ~0.40% in Li, Ta and Sb modified BNT–KNN ((1−x) Bi0.5Na0.5TiO3xK0.47Na0.47Li0.06 Nb0.74Sb0.06Ta0.2O3) system. The morphotropic phase boundary (MPB) of the system between rhombohedral and tetragonal phases lies in the range 0.02 ≤ x ≤ 0.06, beyond which all compositions (up to x < 0.15) were found to be tetragonal. A clear trade-off between the large strain values and achievable d33, kp for a particular composition was noted. It is shown that while for x = 0.03, d33 169 pC/N, kp 49% and strain ~0.13% were obtained, for x = 0.08 with 0.40% strain, d33 and kp values decreased drastically.