Improvement in dielectric and tunable properties of Fe-doped Ba0.6Sr0.4TiO3 thin films grown by pulsed-laser deposition.

Fe-doped Ba(0.6)Sr(0.4)TiO3 (BST) thin films were prepared on Pt/Si substrates by the pulsed-laser deposition method. The concentrations of Fe dopants vary from 0.1 mol% to 1.0 mol%. Our results indicate that a certain amount of Fe dopants can decrease the dielectric loss of BST thin films without causing the significant reduction of the tunability. The leakage current of BST thin films also was reduced by the addition of Fe dopants. BST thin films doped with 0.3 mol% Fe ions show a minimum dielectric loss of 0.88% at 10(6) Hz, which is 1.7% for the undoped BST films. Moreover, the 0.3 mol% Fe-doped BST films reveal a maximum figure of merit (FOM) of 51, indicating the improved comprehensive dielectric and tunable properties.

Effects of La concentration on the structural and dielectric properties of 0.57BiFeO3-0.43PbTiO3 crystalline solutions.

Crystalline solutions of 0.57(Bi(1-x)La(x))FeO(3)-0.43PbTiO(3) (BLF-PT) for x = 0, 0.1, 0.2, and 0.3 were fabricated by the traditional solid state reaction method. X-ray diffraction analysis revealed that the tetragonal torhombohedral phase transformation of BLF-PT occurred with an increase of the La content. The dielectric and ferroelectric properties of BLF-PT were investigated at room temperature for different La contents. BLF-PT revealed strong ferroelectric characteristics for the lower La composition, and transferred to relaxor ferroelectrics for x 0.2. The dielectric constant and remanent polarization were 1461 and 33.5 microC/cm(2), respectively, for BLF-PT of x = 0.2. The dielectric constant and polarization of BLF-PT were enhanced simultaneously with increasing La content. Our results demonstrate that BLF-PT is a competitive piezoelectric ceramic.