Properties Of Barium Titanate Films Research Articles

Physical states and properties of barium titanate films in a plane electric field

The influence of a plane electric field on the phase states of barium titanate thin films under the conditions of forced deformation has been studied. The field dependence of a complete set of material constants has been taken in the region of the c-phase, where polarization losses are absent. The material constants are calculated using equations of the piezoelectric effect derived by linearizing the nonlinear equations of state from the phenomenological; theory for barium titanate. It has been shown that there is a critical value of the field at which the electromechanical coupling coefficient reaches a maximum.

Effect of heat treatment on the microstructure and dielectric properties of plasma-sprayed barium titanate films

Abstract Thick films of barium titanate were produced by using atmospheric plasma spraying, and their microstructures and dielectric properties were analyzed. X-ray diffraction analysis of the coating was performed to study the phase and structural properties. The results showed that the crystalline structures of the initial powder and the produced film were different and the latter displayed some amorphous phase. The percentage of amorphous phase varied with the amount of melted particles. The analysis of dielectric properties of the barium titanate films showed that these films have a minimum relative permittivity of 85 at room temperature. This was increased up to 165 by heat treatment at 1050°C for 3 h, due to the crystallization of amorphous phase and reduction of some of the defects because of the thermal spraying.

Structure and ferroelectric properties of barium titanate films synthesized by sol–gel method

The barium strontium titanate (Ba 0.7Sr 0.3TiO 3, BST) thin films were synthesized by a sol–gel technique on a silicon nanoporous pillar array (Si-NPA) substrate. SEM observation reveals that the as-prepared BST thin film has uniformly covered the inherited pillar-like surface of the Si-NPA substrate. X-ray diffraction analysis indicates that the perovskite phase was able to be generated in the BST film when the annealing temperature was higher than 600 °C. The remnant polarization (Pr) and coercive field (Ec) values were also found to increase with the annealing temperature, with the maxima of 4.57 μC cm −2 for Pr and 7.61 kV mm −1 for Ec at 800 °C, respectively. The measurement of leakage current density against voltage applied suggested that the BST films are excellent insulators along with fair resistance to breakdown, and the mechanism of leakage current was discussed.

Synthesis, Characterization and Electrical Properties of Barium Titanate Films Fabricated by Hydrothermal Method

BaTiO3 films with a thickness up to 3 μm were fabricated under the hydrothermal conditions. It was found that the crystallinity of BaTiO3 increases with the concentration of Ba(OH)2 solutions. Along with the increasing of time, the crystallinity of BaTiO3 increases, reaches the maximum value and then decreases. The measured values of remanent polarization (Pr) and coercive field (Ec) are 1.74μC/cm2 and 24KV/cm. The leakage of the films at 1V is 10-7A/cm2. The dielectric constant and loss tangent of hydrothermal derived BaTiO3 film at a frequency of 1 KHz were 600 and 0.2, respectively.

Dielectric Properties of Barium Titanate Films Fabricated by Aerosol Deposition Method

Dielectric Properties of Barium Titanate Films Fabricated by Aerosol Deposition Method

Characteristics of rf Sputtered Barium Titanate Films on Silicon

The physical and electrical properties of barium titanate films approximately 1 μm thick, prepared by rf sputtering onto silicon substrates in both pure argon and 95% argon–5% oxygen glow discharges were investigated. The argon-oxygen mixture was used to minimize oxygen deficiencies in the films resulting from the possible decomposition of the barium titanate in the glow discharge. Sputtering was carried out in a standard diode system with a water-cooled target of ceramic BaTiO3 at power densities of up to 1.6 W/cm2, at a gas pressure of 7–8×10−3 Torr, and in a magnetic field of 20 G. The substrate holder could be heated to about 650°C during deposition. The deposition rate was typically 100 Å/min and was dependent on the sputtering power density and the substrate temperature. The films were deposited on clean n-type silicon wafers of approximately 5 and 0.01 Ω⋅cm resistivity. Some samples were subjected to a post-deposition heat treatment in nitrogen or oxygen ambients at 1000°C. The deposition rate, crystal structure, and refractive index of the films were investigated as a function of deposition temperature and sputtering gas. The electrical characteristics of the films, including the dielectric constant, loss tangent, conductivity, insulator bulk charge, charge storage at the BaTiO3–SiO2 interface, and ferroelectricity were also investigated.