Structural transition, large strain induced by B-site equivalent doping with Hf4+ ions in BNT-based ceramics

A series of HfO 2 -modified (Bi 0 .475 Na 0 . 405 K 0 . 055 Li 0.015 ) 0.95 Ba 0 . 05 Ti (1- x ) Hf x O 3 ( x  = 0–0.015) lead-free ceramics were prepared. Results of detailed characterizations showed that the addition of HfO 2 had little influence on the grain size, and all of the samples showed the pure perovskite structure. As the Hf 4+ content increases, the samples changed from the normal ferroelectric phase to the ergodic relaxor state at room temperature, and the ceramics with x  = 0.01 showed a high electro-strain of 0.295% at 6 kV/mm. Therefore, this study provides a new insight into of how the HfO 2 addition influences the ferroelectric property of the BNT-based ceramics by B-site substitution.