Composition-dependent structures and properties of (1-x)BaTiO_3-xNaNbO_3 thin films

摘要

(1-x)BaTiO_3-xNaNbO_3 (x = 0.025, 0.050, and 0.075) thin films were prepared on Pt/Ti/SiO_2/Si substrates by pulsed laser deposition. The structures, ferroelectric and dielectric properties were found to be strongly dependent on the composition wherein the ferroelectric polarization, tunability and temperature coefficient of capacitor (TCC) decrease with increasing x. At an applied field of 390 kV/cm, the room-temperature tunability are 67%, 38%, and 7% for the films with x = 0.025, 0.050, and 0.075, respectively. Especially, the tunability reaches 78% with a field of 610 kV/cm for the films with x = 0.025. The measured negative TCC values of these films are 1.7 x 10~(-3)/℃, 1.0 x 10~(-3)/℃, and 8.9 x 10~(-4)/℃, respectively.