Dielectric Properties Of BaTiO Research Articles

Microstructure and Dielectric Properties of BaTiO<sub>3</sub> Prepared by Colloidal Processing

An ultrafine BaTiO3 powder of 80 nm diameter was consolidated to powder compacts with 58% TD and uniform structures by filtration of 2-methoxyethanol, 2-ethoxyethanol or methanol suspension and subsequent isostatic pressing under a pressure of 294MPa. These compacts were sintered into dense BaTiO3 ceramics with average grain sizes of 1-2μm (>95% TD) within 2h at 1200-1250°C. Increasing the heating rate to the sintering temperatures of 1000-1300°C was effective in increasing the density. Grain growth from 0.5 to 2μm caused significant increase of the c-parameter of BaTiO3, resulting in the increase of tetragonality (c/a ratio). The phase transition from tetragonal to cubic form at room temperature was estimated to occur below 0.4μm average grain size. The relative dielectric constant (e′) at room temperature was highest (≈6000 at 1kHz) in the high-density BaTiO3 with an average grain size of 1.4μm, sintered at 1200°C. Increase of the grain size to 2.3μm in dense BaTiO3 caused the decrease of the e′ value. The low-density and small-grained (0.5μm) BaTiO3 also showed a low e′ value (1400 at 1kHz). The e′ values of all samples were almost independent of frequency in the range of 100Hz to 500kHz. The dielectric loss was strongly affected by the porosity and decreased at higher density. The decrease of grain size reduced the e′ values below and above the Curie temperature, leading to the broadening of e′ in a wide temperature range (18-220°C).

Microstructure and dielectric properties of BaTiO3doped with niobium and cobalt

Abstract The influence of Niobium and Cobalt on the microstructural and dielectric properties of BaTiO3 with different Ba/Ti ratio was studied. The dopants were coprecipitated over the BaTiO3 particles. The dopants located at the grain boundaries act as grain inhibitors. On the contrary, the dopants which are incorporated in solid solution produce exaggerated grain growth. The existence of glass-forming impurities in the BaTiO3 starting powders, favours such a behaviour. A higher size of the starting particles with a stoichiometric ratio Ba/Ti≤1 promotes the obtaining of materials with X7R capacitor characteristics. The increase of the dopant content produces a higher incorporation of the dopant cations on the perovskite lattice, and, a subsequent decrease of the Curie temperature.

Microstructural Examination and Dielectric Properties of BaTiO<sub>3</sub> with Addition of CaO

Microstructural Examination and Dielectric Properties of BaTiO<sub>3</sub> with Addition of CaO

Microstructural and dielectric properties of BaTiO 3 thin films prepared by atom beam sputtering

Amorphous BaTiO 3 films were deposited on glass plates overlayered with platinum by atom beam sputtering at different substrate temperatures, and the effects of post-annealing at 923 K on the crystallization behavior and dielectric properties investigated. The possibility for improvement of dielectric properties of thin films through the crystallization of amorphous phases is discussed.

Point defect chemistry and dielectric properties of BaTiO3

Abstract Dielectric measurements, X-ray diffraction and S.E.M. observations performed on Ba1 -xCaxTiO3 and BaTi1 - yZryO3 are reported with the aim to understand the role of calcium and zirconium introduced in small amount in BaTiO3 in order to increase and flatten the ε = f(T) response. It is shown that zirconium allows to move the transitions temperatures whereas calcium essentially governs the grain size, thus, both influence the value of the dielectric constant.

Influence de l'ajout de BaLif 3 sur les proprietes cristalliongraphiques et dielectriques de BaTiO 3

The study of the BaTiO 3-BaLiF 3 system in platinium-sealed tubes has allowed one to determine the influence of the addition of BaLiF 3 on the crystallographic and dielectric properties of BaTiO 3. The ferroelectric Curie temperature decreases as the rate of substitution increases. A ceramic with a composition Ba(Ti 0.965Li 0.035)O 2.895F 0.105 has a Curie temperature T C close to 280 K. The corresponding maximum of the permittivity ϵ′ r max. at T C increases from 1000 to 5600 when the sintering temperature rises from 850 to 1300°C. This enhancement has been compared with that observed for a ceramic sintered from BaTiO 3 and LiF at 930°C (ϵ′ r max. > 6000). It appears that the sintering process in that case cannot be due mainly to formation of a solid solution between BaTiO 3 and BaLiF 3.

The influence of a sinusoidal electric field on the dielectric properties of BaTiO 3 films

Investigations were made of the influence of amplitude E ∼ and frequency v of sinusoidal electric fields (measurement fields) on the permittivity ε, loss tangent tan δ, spontaneous polarization P s and coercive field E c of BaTiO 3 films obtained by the annealing method. It was found that the dielectric properties of the films are markedly dependent on the parameters of the electric measurement field and certain anomalies in the relations P s = f( E ∼) and E c = f( v) were observed.

Effect of high hydrostatic pressure on the dielectric properties of BaTiO3 single crystals

AbstractThe dielectric permittivity ϵ of BaTiO3 single crystals versus the temperature T at different hydrostatic pressure σ, and ϵ(σ) at different T, was measured. The highest σ achieved was 12 800 kg/cm2, between 22 °C and 180 °C. At σ < 3500 kg/cm2, the Curie point Tc decreases at a rate of −4.3 × 10−3 °C cm2/kg which ceases to be constant for σ > 3500 kg/cm2. The Curie‐Weiss temperature falls with growing σ. At higher σ, the Curie constant rises with growing σ. The ϵ(σ) graphs at constant T below 120 °C exhibit maxima related to an induced phase transition. Above 120 °C, ϵ decreases with growing σ. „Memory of pressure”︁ is observed on removal of high hydrostatic pressure.

Effect of Iron Group Ions on the Dielectric Properties of BaTiO3 Ceramics

Effect of Iron Group Ions on the Dielectric Properties of BaTiO₃ Ceramics