Growth and properties of epitaxial (Bi, K)TiO 3 -Bi(Mg, Ti)O 3 -BiFeO 3 piezoelectric films prepared by using a PLD method

Epitaxial films of (1.0 − x )((Bi 0.5 , K 0.5 )TiO 3 -Bi(Mg 0.5 , Ti 0.5 )O 3 )- x BiFeO 3 (BKT-BMT-BFO) on silicon substrates were fabricated by using a pulsed laser deposition method, and their structures and piezoelectric properties were evaluated. The epitaxial relationship was (100) 〈100〉BKT-BMT-BFO//(100) 〈100〉Pt//(100) 〈100〉yttria-stabilized ZrO 2 //(100) 〈001〉Si. The BKT-BMT-BFO film with x = 0.5 exhibited a tetragonal structure with a large lattice anisotropic parameter ( c / a ), reaching a maximum value of 1.095 on LaNiO 3 buffer layer, due to a substrate-induced epitaxial strain and tetragonal BiFeO 3 . It showed high ferroelectricity with remanent polarization ( P r ) even reaching 90 μC cm −2 . The transverse piezoelectric coefficient (| e 31, f |) and figure of merit ( e 31 , f 2 /( ε 0 ε r )) of the BKT-BMT-BFO film s were up to 7.4 C cm −2 and 60.7 GPa, respectively.