Search

Highly uniformed barium-strontium titanate nanotube arrays were fabricated using a porous anodic aluminum oxide template from a barium-strontium titanate sol—gel solution. Electron microscope results showed that nanotubes with uniform length and diameter were obtained. The diameters and lengths of these nanotubes were dependent on the pore diameter and the thickness of the applied anodic aluminum oxide template. High resolution transmission electron microscopy and the selected-area electron diffraction pattern investigations demonstrated the perovskite structure and the polycrystalline of the fabricated barium-strontium titanate nanotubes. The characterization of the electrical and dielectric properties had also been made. Compared to thin film material, the intrinsic leakage current density is almost the same. Besides, at 30 ?C, the dielectric constant and dielectric loss of the fabricated nanotube is 80 and 0.027 at 1 MHz respectively.

We have investigated the preparation and properties of Bi3.4Ce0.6Ti3O12 thin films. The Bi3.4Ce0.6Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The thin films showed a perovskite phase and dense microstructure. The dielectric constant and the dissipation factor of the Bi3.4Ce0.6Ti3O12 thin films were about 172 and 0.031 at 1 kHz, respectively. The 2Pr and 2Ec of the Bi3.4Ce0.6Ti3O12 thin films were 67.1 μC/cm2 and 299.7 kV/cm, respectively, under an applied field of 600 kV/cm. The Bi3.4Ce0.6Ti3O12 film did not show fatigue up to 4.46×109 switching cycles at a frequency of 1 MHz, and showed good insulating behavior according to the test of leakage current.

We have investigated the preparation and properties of Bi4Zr0.5Ti2.5O12 thin films on the LaNiO3 bottom electrode. The Bi4Zr0.5Ti2.5O12 thin films were fabricated on the LaNiO3 bottom electrode using the sol–gel method. The structure and morphology of the films were characterized using x-ray diffraction and scanning electron microscopy. The results show that the films are a perovskite phase with a dense microstructure. The 2Pr and 2Vc of the Pt/BZT/LaNiO3 capacitor are 28.2 µC cm−2 and 14.7 V respectively under the applied voltage of 25 V. After the switching of 1 × 1010 cycles, the Pr value decreases to 87% of its pre-fatigue values. The dielectric constant and the dielectric loss are about 204 and 0.024 at 1 kHz, respectively. The films show good insulating behaviour according to the test of leakage current.

The c-axis oriented Bi3.15Nd0.75Ti3O12(BNT) ferroelectric thin films were grown on Si(100) substrates by pulsed lase r deposition with La0.5Sr0.5CoO3/CeO2/Y0.18Zr0.91O2.01 multi-heterostructure as buf fer layer. X-ray diffraction and scanning electron microscopy were used to deter mine the microstructure, orientation and morphology of the multi-layer films. Th e influence of deposition temperatures and the partial oxygen pressure on the mi crostructure, orientation and morphology of the BNT films were investigated and the optimal deposition parameters were determined. The BNT multi-layer thin film s deposited under optimal condition have good electric properties. The C-V patte rn of the BNT multilayer thin films deposited under optimal deposition condition s has the typical butterfly-like shape, suggesting that the films have good pola rization-reversion storage properties. The correlation between the ferroelectric properties and the orientations of the BNT films is discussed.

The Bi 4 Ti 3 O 12 and Bi 3.25 La 0.75 Ti 3 O 12 thin films are prepared on the Pt/Ti/SiO 2 /Si substrate using sol-gel method. The structures Pt/Bi 3.25 La 0.75 Ti 3 O 12 /Pt and Pt/Bi 4 Ti 3 O 12 /Pt are fabricated. The effects of La doping on the microstructures, and ferroelectric properties of Bi 4 Ti 3 O 12 films are investigated. The 2 Pr with test voltage 6V for the sample annealed at 700℃ increased from 12.5 μC/cm 2 to 18.6 μC/cm 2 , and 2 Vc is still 2.8 V when the La 3+ ions occupy part of Bi 3+ sites. The Bi 3.25 La 0.75 Ti 3 O 12 films showed fatigue-free behavior. The mechanism of improvement of La-doped Bi 4 Ti 3 O 12 ferroelectric thin films is discussed.

The structures and the epitaxial growth behavior of the La0.5Sr0.5CoO3 thin films prepared by pulsed laser deposition on various substrates and at different deposition temperatures have been studied systematically.Epitaxial growth of the LSCO thin films with low resistivity and metallic conducting features has been demonstrated on the substrates of LaAlO3,SrTiO3 and MgO.Studies reveal that for the epitaxial growth of LSCO thin films,700—800℃ are the optimal deposition temperatures and LaAlO3 is the optimal substrate.Emphases are laid on the discussions of the influences and the mechanisms of substrates and deposition temperatures on the epitaxial growth of the LSCO thin films.

Based on the ahievement of epitaxial growth in several Perovskite oxide films,we discuss the importance of substrate temperature (Ts) and substrate material in the epitaxial growth of per-ovskite oxide thin films.Influences of Ts on growth orientation and epitaxial threshold temperature were observed.The results indicate that during the growth of the oxide films the phase formation and growth dynamics should be taken into considera tion.The threshold temperature for epitaxial growth depends on the substrate materials.This demonstrates the influence of substrate material on the initial nucleation and epitaxial growth.