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

Abstract

In this work we demonstrate a large electric field‐induced bipolar strain ~0.40% in Li , Ta and Sb modified BNT – KNN ((1− x ) Bi 0.5 Na 0.5 TiO 3 – x K 0.47 Na 0.47 Li 0.06 Nb 0.74 Sb 0.06 Ta 0.2 O 3 ) 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 d 33 , k p for a particular composition was noted. It is shown that while for x = 0.03, d 33 169 pC/N, k p 49% and strain ~0.13% were obtained, for x = 0.08 with 0.40% strain, d 33 and k p values decreased drastically.