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

A series of HfO2-modified (Bi0.475Na0.405K0.055Li0.015)(0.95)Ba(0.05)Ti((1-x))HfxO(3) (x = 0-0.015) lead-free ceramics were prepared. Results of detailed characterizations showed that the addition of HfO2 had little influence on the grain size, and all of the samples showed the pure perovskite structure. As the Hf4+ 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 HfO2 addition influences the ferroelectric property of the BNT-based ceramics by B-site substitution.