“…Recently, considerable efforts have been carried out to address this problem mentioned above , [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] such as: (1) adding oxide additives, e.g., MnO 2 , 16,20,21 Bi 2 O 3 , 18,22 CuO, 23 La 2 O 3 , 24 and so on, have been added to improve the resistivity as well as the piezoelectric properties. (2) Building ternary system, e.g., BF- 17,25,26 BF-BT-Bi 0.5 K 0.5 TiO 3 , 27 and so on.…”