Tunability and permittivity-temperature characteristics of highly (100) oriented compositionally graded (Ba0.7Sr0.3)(SnxTi1−x)O3 thin films grown by pulse-laser deposition

Compositionally graded (Ba0.7Sr0.3)(SnxTi1−x)O3 (BSSnT) (x=0.1, 0.2, 0.3, and 0.4) thin films were prepared by pulse-laser deposition on (La0.7Sr0.3)CoO3∕LaAlO3 substrates. A highly (100) oriented structure was obtained for both the upgraded (x increased from the bottom layer) and downgraded (x decreased from the bottom layer) configurations. The tunabilities are 31% and 35% for up- and downgraded BSSnT thin films at 300kV∕cm, respectively. Both the up- and downgraded BSSnT thin films exhibit near linear permittivity-temperature characteristics in the temperature range of −150to150°C. Fine grain size and graded configuration are believed to be responsible for this dielectric behavior.