“…[1][2][3][4][5][6] However, in the past two or three decades, due to the health and environmental concerns, a variety of Pb-free perovskite ferroelectric materials have attracted a lot of positive attention. [7][8][9][10] Among them, (Bi 1=2 Na 1=2 TiO 3 ) (NBT), [11][12][13][14][15][16] BaTiO 3 (BT), [17][18][19][20][21][22] and (K 0:5 Na 0:5 )NbO 3 (KNN) [23][24][25][26] -based systems therefore have been widely investigated, especially focusing on the compositions near morphotropic phase boundary (MPB) or polymorphic phase transition (PPT) in order to achieve superior dielectric and piezoelectric properties. 2,3 For example, although NBT exhibits high piezoelectric properties and fascinating phase transition behavior, its low depolarization temperature, high ionic conductivity and huge coercive field (E c ) limit its application.…”