Microstructures and Dielectric Constants of Ba0.05SrxCa0.95-xTiO3 (x=0, 0.225, 0.475, 0.725 and 0.95) Synthesized by the Solution Combustion Technique

2018 ◽  
Vol 766 ◽  
pp. 197-204
Author(s):  
Oratai Jongprateep ◽  
Nicha Sato ◽  
Sansanee Boonsalee ◽  
Jae Hwan Pee
Keyword(s):  
Dielectric Constant ◽  
Fine Particles ◽  
Dielectric Material ◽  
Grain Morphology ◽  
Calcium Titanate ◽  
Dielectric Constants ◽  
Solution Combustion ◽  
Strontium Content ◽  
Barium Strontium ◽  
Combustion Technique

Barium strontium calcium titanate is a dielectric material exploited in fabrication of electronic devices such as capacitors, signal filters and satellite components. Dielectric properties can be enhanced through compositional and microstructural control. This study, therefore, aimed at synthesizing barium strontium calcium titanate (Ba0.05SrxCa0.95-xTiO3, where x = 0, 0.225, 0.475, 0.725 and 0.95) powders by a solution combustion technique. The powders were pressed, sintered at 1450°C and tested for their properties. Experimental results revealed that strontium content did not significantly influence chemical composition, particle sizes and density. All powders exhibited a single phase corresponding to Ba0.05SrxCa0.95-xTiO3with fine particles with the average size smaller than 0.4 micrometer. All sintered samples had density higher than 95% of theoretical density. On the contrary, the results indicated that strontium content affected grain size, grain morphology and dielectric constant of the sintered samples. The highest dielectric constant of 531 (at 1 MHz) was achieved in the Ba0.05Sr0.225Ca0.725TiO3. Dielectric constant was discussed with respect to microstructure.

Dielectric Properties Enhancement in Polybenzoxazine Composite at Multi-Frequency Range

2008 ◽  
Vol 55-57 ◽  
pp. 105-108 ◽  
Author(s):  
Nidchakarn Krueson ◽  
H. Manuspiya ◽  
Pitak Laoratanakul ◽  
H. Ishida
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Barium Strontium Titanate ◽  
Dielectric Material ◽  
Dielectric Constants ◽  
Frequency Range ◽  
Barium Strontium ◽  
Silane Coupling ◽  
Constant Improvement

This research proposed a novel nano barium strontium titanate (BST) powder- polybenzoxazine composite as a new dielectric material. In this work, the dielectric properties of a surface-treated BST powder-polybenzoxazine composite were studied. The surface of the BST powders were modified by using three different chemicals: 3-aminopropyl-trimethoxysilane, benzoxazine monomer and phthalocyanine. The distribution of the BST powders in the polybenzoxazine matrix was observed by SEM. The dielectric constants of the composites with a function of frequency (1 kHz–10 MHz) were investigated. It was found that the composites with modified BST powders showed good distribution in the polybenzoxazine matrix, and the dielectric constants were also much enhanced than those with untreated BST powders. In comparisons among the three modification methods, the composite with the silane coupling modified BST powder showed significantly in dielectric constant improvement while the composite with the benzoxazine and phthalocyanine modified BST powders displayed lower dielectric loss due to the modified powder dispersed well in the polybenzoxazine matrix.

CVD Diamond as Dielectric Material for Capacitor Applications

1998 ◽  
Vol 512 ◽  
Author(s):  
S. Heidger ◽  
S. Fries-Carr ◽  
J. Weimer ◽  
B. Jordan ◽  
R. Wu
Keyword(s):  
Dielectric Constant ◽  
Loss Tangent ◽  
Microwave Plasma ◽  
Dielectric Material ◽  
Chemical Vapor ◽  
Temperature Stability ◽  
Cvd Diamond ◽  
Dielectric Constants ◽  
Plasma Chemical Vapor Deposition ◽  
Deposition Parameters

ABSTRACTDiamond films synthesized using Microwave Plasma Chemical Vapor Deposition (MWCVD) were evaluated for use as dielectric material for high power and high temperature capacitors. The effect that the deposition parameters and annealing have on the frequency and temperature stability of the electronic properties was investigated. Dielectric constants ranging between 8.0 and 4.2 and resistivities between 1× 108 ohm-cm and 5×1014 ohm-cm were obtained. Diamond produced using less than 6.6% methane had very stable dielectric constants over the frequency range of 100 Hz to IMHz, and the loss tangent was less than 0.01. Adding oxygen to the precursor gas increased the dielectric constant and lowered the loss tangent of CVD diamond, but the resistivity was also lowered. As the temperature increased to 300°C, the dielectric constant and loss tangent increased. However, when diamond was annealed to 700°C, there was less than a 5% change in the dielectric constant from 23°C to 300°C.

Theoretical Calculations of the Nonlinear Dielectric Function of Inhomogeneous Thin Films

1990 ◽  
Vol 193 ◽  
Author(s):  
Steven M. Risser ◽  
Kim F. Ferris
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Theoretical Calculations ◽  
Grain Morphology ◽  
Dielectric Constants ◽  
Dielectric Films ◽  
Internal Electric Field ◽  
Approximate Methods ◽  
The Real ◽  
Defect Phase

ABSTRACTThe optical response of thin dielectric films can be influenced by grain morphology and the presence and distribution of defects. In the limit of random defects and small electric field amplitudes, approximate methods exist to model the real part of the dielectric constant in terms of volume fractions and bulk dielectric constants of the film components. Explicit inclusion of nonlinear polarizabilities and details of the microstructure, such as particle phase, shape, and orientation requires a more exact approach.We have developed a method to self-consistently determine the local internal electric field and polarization in the long wavelength limit for model films with a random distributions of defects of arbitrary phase and orientation. From this we have calculated the real part of the dielectric constant as a function of nonlinear polarizability of the components, and have shown the effect of defect phase and orientation on the dielectric constant of the film.

scholarly journals Calcium titanate ceramics obtained by combustion synthesis and two-step sintering

2020 ◽  
Vol 52 (4) ◽  
pp. 491-502
Author(s):  
Kanchana Maitreekeaw ◽  
Tawat Chanadee
Keyword(s):  
Dielectric Constant ◽  
Combustion Synthesis ◽  
Xrd Analysis ◽  
Calcium Titanate ◽  
Single Step ◽  
Dielectric Constants ◽  
Sintered Ceramic ◽  
Relaxation Polarization ◽  
Titanate Ceramics ◽  
Titanate Ceramic

Calcium titanate powder was successfully prepared from duck eggshell and anatase titanium dioxide with a magnesium inductant via combustion synthesis in argon. As-combusted products were leached with diluted HCl. In XRD analysis, as-leached powders exhibited a major phase of CaTiO3 with a perovskite structure. The particle size, observed by SEM, was approximately 240 nm. As-leached powders were densified by single-step (SST) and two-step sintering (TSS) to produce calcium titanate ceramics. The first step of all TSS conditions was fixed at 1350C and holding times (t1) at this temperature were varied up to 120 min. Calcium titanate ceramic obtained from holding for 120 min had a grain size of 2.18 ?m, relative density of 86.68% and a dielectric constant of 92. Two-step sintered ceramic had the highest density (95.73%) and best dielectric properties (dielectric constant = 110, dielectric loss = 0.02) when the holding temperature (T2) was 1250?C. Calcium titanate ceramics processed by two-step sintering had denser microstructures and higher dielectric constants than single-step sintered ceramic due to grain boundary diffusion and the simplicity of relaxation polarization.

Chemical Composition-Microstructure-Dielectric Constant Relations of Mg-Doped Calcium Titanate Synthesized by Solid State Reaction Technique

2017 ◽  
Vol 751 ◽  
pp. 390-396
Author(s):  
Oratai Jongprateep ◽  
Nicha Sato ◽  
Jednupong Palomas ◽  
Pongsakorn Jantaratana
Keyword(s):  
Dielectric Constant ◽  
Chemical Composition ◽  
Solid State ◽  
Solid State Reaction ◽  
Secondary Phase ◽  
Dielectric Materials ◽  
Calcium Titanate ◽  
Dielectric Constants ◽  
Composition Analysis ◽  
X Ray Diffraction

It has been generally accepted that doping of dielectric materials could significantly contribute to compositional and microstructural evolution, which consequently lead to alteration in dielectric properties. In this study, the effects of adding magnesium (Mg) at 5,10 and 20at% on the chemical composition, microstructure and dielectric constant of calcium titanate (CaTiO3) synthesized by solid state reaction was assessed. Chemical composition analysis using an X-ray diffraction technique CaTiO3 doped with 5 at% Mg has been found to contain a single phase whereas samples doped with 10 and 20 at% Mg both exhibited apparent secondary phase (MgO). Microstructural examination however, revealed that no significant variation in particle size, grain size and density were evident among the samples of different Mg contents. Average dielectric constants obtained from the entire samples ranged from 245.9 to 387.6 (at 1 MHz) and the sample with the highest dielectric constant was that doped with 5 at% Mg. Enhancement of dielectric constant in the samples with the lowest level of Mg doping has been attributed largely to the homogeneity of its chemical composition.

Effects of Ca Addition on Chemical Composition, Microstructure and Dielectric Properties of BaTiO3

2014 ◽  
Vol 575 ◽  
pp. 231-237 ◽  
Author(s):  
Oratai Jongprateep ◽  
Tunchanoke Khongnakhon ◽  
Pongsakorn Jantaratana ◽  
Sansanee Rugthaicharoencheep
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Chemical Composition ◽  
Barium Titanate ◽  
High Energy ◽  
Dielectric Constants ◽  
High Energy Density ◽  
Composition Analysis ◽  
Secondary Phases ◽  
Solution Combustion

Owing to its high dielectric constant, barium titanate is a material commonly employed in fabrication of high energy density capacitors. Dielectric properties required for practical applications can be attained in barium titanate with desired chemical composition and microstructure. This study, therefore, aims at examining effects of additive contents on formation of secondary phases, microstructure and dielectric properties of BaTiO3 and BaTiO3 with 20-40 at% Ca. Chemical composition analysis revealed that single-phase BaTiO3 powder could be attained by the solution combustion technique. However, the powder with high Ca content exhibited large quantities of secondary phases. Dielectric property measurements of the uniaxially pressed powders indicated that dielectric constants could be enhanced with low Ca content. On the contrary, dielectric constant significantly degraded with high Ca content. This was attributed to formation of large quantities of secondary phases, coarse grain size and low density. Values of dielectric loss of all materials were lower than 1%.

Bismuth titanium indium antimony oxide: A low-temperature-coefficient, high-K dielectric material

2000 ◽  
Vol 15 (12) ◽  
pp. 2672-2676
Author(s):  
R. J. Cava ◽  
J. J. Krajewski ◽  
Y. L. Qin ◽  
H. W. Zandbergen
Keyword(s):  
Dielectric Constant ◽  
Dielectric Material ◽  
Antimony Oxide ◽  
Dielectric Constants ◽  
X Ray Diffraction ◽  
X Ray ◽  
High K ◽  
Polycrystalline Ceramics ◽  
High K Dielectric ◽  
End Members

The 1 MHz dielectric properties for mixed-phase polycrystalline ceramics in the system Bi4Ti3O12–Bi(InxSb1x)O3 were reported. In the vicinity of ambient temperature, the dielectric constants for the Sb and In end-members were approximately 430 and 160, respectively, and the temperature coefficients of dielectric constant (TCKs) were approximately -7600 and +430 ppm/deg. At an overall composition of Bi4Ti3O12:Bi(In0.37Sb0.63)O3 a dielectric constant of 144 and a low TCK were found. Powder x-ray diffraction and electron microscopy analyses indicated that the optimal composition contained three major phases. Deviation of any of the elements from the above ratio leads to degradation of the properties.

scholarly journals Electrocatalytic Properties of Calcium Titanate, Strontium Titanate, and Strontium Calcium Titanate Powders Synthesized by Solution Combustion Technique

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Oratai Jongprateep ◽  
Nicha Sato ◽  
Ratchatee Techapiesancharoenkij ◽  
Krissada Surawathanawises
Keyword(s):  
Strontium Titanate ◽  
Sodium Nitrite ◽  
Dielectric Materials ◽  
Calcium Titanate ◽  
Bandgap Energy ◽  
Solution Combustion ◽  
Electrocatalytic Properties ◽  
Surface Areas ◽  
Electrocatalytic Performance ◽  
Combustion Technique

Calcium titanate (CaTiO3), strontium titanate (SrTiO3), and strontium calcium titanate (SrxCa1−xTiO3) are widely recognized and utilized as dielectric materials. Their electrocatalytic properties, however, have not been extensively examined. The aim of this research is to explore the electrocatalytic performance of calcium titanate, strontium titanate, and strontium calcium titanate, as potential sensing materials. Experimental results revealed that CaTiO3, SrTiO3, and Sr0.5Ca0.5TiO3 powders synthesized by the solution combustion technique consisted of submicrometer-sized particles with specific surface areas ranging from 4.19 to 5.98 m2/g. Optical bandgap results indicated that while CaTiO3 and SrTiO3 had bandgap energies close to 3 eV, Sr0.5Ca0.5TiO3 yielded a lower bandgap energy of 2.6 eV. Cyclic voltammetry tests, measured in 0.1 M sodium nitrite, showed oxidation peaks occurring at 0.58 V applied voltage. The highest peak current was observed in Sr0.5Ca0.5TiO3 powder. The superior electrocatalytic performance of Sr0.5Ca0.5TiO3 might be attributed to lower bandgap energy, which consequently facilitates higher electron transfer. Electrocatalytic performance of Sr0.5Ca0.5TiO3 was subsequently reexamined in a wider concentration range of sodium nitrite. The results revealed that the material responded linearly to nitrite solution in the range of 0.1 mM to 0.1 M and exhibited sensitivity ranging from 3.117 to 0.040 μA/mM, in the entire tested nitrite concentrations. The results suggest that Sr0.5Ca0.5TiO3 could also be used for nitrite detection.

Skin–core structured fluorinated MWCNTs: a nanofiller towards a broadband dielectric material with a high dielectric constant and low dielectric loss

2018 ◽  
Vol 6 (9) ◽  
pp. 2370-2378 ◽  
Author(s):  
Yang Liu ◽  
Cheng Zhang ◽  
Benyuan Huang ◽  
Xu Wang ◽  
Yulong Li ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
High Dielectric Constant ◽  
Dielectric Material ◽  
Epoxy Composite ◽  
Low Dielectric ◽  
High Dielectric

A novel skin–core structured fluorinated MWCNT nanofiller was prepared to fabricate epoxy composite with broadband high dielectric constant and low dielectric loss.

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