“…Different dopants, such as Nd, Sm, Eu, La, Sm, Zn, Ta, and so on, have been explored to enhance the piezoelectric response. [18][19][20][21][22][23][24][25] Despite several significant efforts, the best reported k p and d 33 values for the doped [Bi 0.5 Na 0.41 K 0.09 ]TiO 3 are 0.29 and 150 pC N À1 , respectively. On the contrary, Zhang et al [26] achieved the similar values for the piezoelectric coefficients in pure [Bi 0.5 Na 0.41 K 0.09 ]TiO 3 by optimizing the material synthesis process.…”