Hard piezoelectric properties of lead‐free BiFeO <sub>3</sub> –BaTiO <sub>3</sub> ceramics
Myang Hwan Lee, Hae In Choi, Da Jeong Kim, Ji Su Kim, Tae Kwon Song
Abstract
Abstract Hard piezoelectric properties are investigated in lead‐free BiFeO 3 –BaTiO 3 (BF–BT) ceramics. Rhombohedral (R) phase ceramics of (1 – x )BF– x BT ( x = 0.20–0.30) were prepared using a conventional solid‐state reaction and water‐quenching process. The R structure is observed in x = 0.20–0.275, and the R and tetragonal phases coexist at x = 0.30. The piezoelectric charge sensor coefficient ( d 33 ) and electromechanical planar coupling factor ( k p ) increase with increasing BT content, whereas the mechanical quality factor ( Q m ) decreases. The x = 0.20 ceramic shows the best hard piezoelectric properties: the highest Q m = 403 and the highest T C = 607°C. In contrast, x = 0.30 ceramic shows soft piezoelectric properties: d 33 = 301 pC/N and k p = 0.33 with T C = 510°C. These results show that the BF–BT system in R‐phase‐rich region has good hard piezoelectric properties for transducer applications.