scholarly journals The influence of Bi content on dielectric properties of Bi4–xTi3O12–1.5x ceramics

2017 ◽  
Vol 07 (03) ◽  
pp. 1750021 ◽  
Author(s):  
Hui Gong ◽  
Xiying Ke ◽  
Shuqin Yang ◽  
Zhaozhi Li ◽  
Huyin Su ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Curie Temperature ◽  
Dielectric Materials ◽  
Layered Perovskite ◽  
Low Loss ◽  
Solid State Method ◽  
Spectra Analysis ◽  
Perovskite Type ◽  
Perovskite Type Structure

A kind of lead-free dielectric materials, such as the bismuth layered perovskite-type structure of Bi[Formula: see text]Ti3O[Formula: see text], was prepared by the conventional solid-state method at 800[Formula: see text]C and sintered at 1100[Formula: see text]C. The variation of structure and electrical properties with different Bi concentration was studied. All the Bi[Formula: see text]Ti3O[Formula: see text] samples exhibited a single structured phase. SEM could be a better approach to present the microstructure of Bi[Formula: see text]Ti3O[Formula: see text] ceramics. It could be found that the grain size of Bi[Formula: see text]Ti3O[Formula: see text] sintered at 1100[Formula: see text]C was smaller than that of others among the five samples through grain size mechanics. Through impedance spectra analysis, we knew, when the Bi content was fixed, that the dielectric constant and the loss values increased with the decrease of frequency. The Curie temperature of the five samples was about 670[Formula: see text]C. In particular, while at the frequency of 100[Formula: see text]kHz, the lowest loss was 0.001 when Bi content was 3.98. The Bi[Formula: see text]Ti3O[Formula: see text] ceramics with the minimum grain size had highest dielectric constant and the relatively low loss. Due to its high Curie temperature, high permittivity and low loss, the Bi4Ti3O[Formula: see text] (BIT) ceramics have a broad application prospect in high density memory, generator, sensor, ferroelectric tunnel junctions and so on.

scholarly journals Crystal structures of isotypic poly[bis(benzimidazolium) [tetra-μ-iodido-stannate(II)]] and poly[bis(5,6-difluorobenzimidazolium) [tetra-μ-iodido-stannate(II)]]

2014 ◽  
Vol 70 (10) ◽  
pp. 178-182 ◽  
Author(s):  
Iwan Zimmermann ◽  
Tony D. Keene ◽  
Jürg Hauser ◽  
Silvio Decurtins ◽  
Shi-Xia Liu
Keyword(s):  
Hydrogen Bonds ◽  
Point Group ◽  
Van Der Waals Interactions ◽  
Group Symmetry ◽  
Layered Perovskite ◽  
Out Of Plane ◽  
Related Compounds ◽  
Perovskite Type ◽  
Inorganic Layers ◽  
Perovskite Type Structure

The isostructural title compounds, {(C7H7N2)2[SnI4]}n, (1), and {(C7H5F2N2)2[SnI4]}n, (2), show a layered perovskite-type structure composed of anionic {[SnI4]2−}nsheets parallel to (100), which are decorated on both sides with templating benzimidazolium or 5,6-difluorobenzimidazolium cations, respectively. These planar organic heterocycles mainly form N—H...I hydrogen bonds to the terminal I atoms of the corner-sharing [SnI6] octahedra (point group symmetry 2) from the inorganic layer, but not to the bridging ones. This is in contrast to most of the reported structures of related compounds where ammonium cations are involved. Here hydrogen bonding to both types of iodine atoms and thereby a distortion of the inorganic layers to various extents is observed. For (1) and (2), all Sn—I—Sn angles are linear and no out-of-plane distortions of the inorganic layers occur, a fact of relevance in view of the material properties. The arrangement of the aromatic cations is mainly determined through the direction of the N—H...I hydrogen bonds. The coherence between organic bilayers along [100] is mainly achieved through van der Waals interactions.

Study on Microstructure and Properties of BTBY Piezoelectric Ceramics with High Curie Temperature

2010 ◽  
Vol 156-157 ◽  
pp. 1541-1544
Author(s):  
Bo Li ◽  
Feng Gao ◽  
Liang Liang Liu ◽  
Bei Xu
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Curie Temperature ◽  
Grain Morphology ◽  
High Curie Temperature ◽  
Microstructure And Properties ◽  
New Phase ◽  
Dielectric Relaxor

(1-x)(0.6BIT-0.4BT)-xBiYbO3(BTBY) ceramics with high Curie temperature were prepared by the conventional processing. The effect of BiYbO3 content on the microstructure and electrical properties was investigated. The results show that the main phase of BTBY ceramics is BIT-BT, and a new phase BaBi4Ti4O15 (BBT) appeared. The grain morphology of BTPY ceramics are platelike and the grain size was significantly increased with increasing content of BiYbO3 .Tc of all the BTBY samples are above 440 . The BTBY ceramics show obvious dielectric relaxor characteristic. The dispersion factor γ, the dielectric constant εr, and the dielectric loss tanδ decreased with increasing the content of BiYbO3. When the content of BiYbO3 is 0.06, the optimal properties of BTBY ceramics are obtained, Tc is 457 , εr is 165, tanδ is 0.0223 and d33 is 10 pC·N-1.

Ion-Exchangeable Oxides with Layered Perovskite Structures as Photocatalysts for Overall Water Splitting

1996 ◽  
Vol 454 ◽  
Author(s):  
T. Takata ◽  
K. Shinohara ◽  
A. Tanaka ◽  
M. Hara ◽  
J. N. Kondo ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Water Splitting ◽  
Alkaline Solution ◽  
Layered Perovskite ◽  
Stoichiometric Ratio ◽  
Aqueous Alkaline Solution ◽  
Overall Water Splitting ◽  
The One ◽  
Perovskite Type ◽  
Perovskite Type Structure

ABSTRACTA novel series of photocatalysts for an overall water splitting is reported. The catalysts have a layered perovskite type structure with a general formula of A2−xLa2Ti3−xNbxO10 (A = K, Rb, Cs; x = 0, 0.5, 1.0). The catalysts, except for the one with x=1.0, are spontaneously hydrated, and the band gap irradiation induced efficient evolution of H2 and O2 in a stoichiometric ratio from an aqueous alkaline solution when a proper amount of Ni loading was made. The reaction mechanism of water splitting on these catalysts is discussed on the bases of the structural study of the catalysts.

A colossal dielectric constant of an amorphous TiO2:(Nb, In) film with low loss fabrication at room temperature

2014 ◽  
Vol 2 (33) ◽  
pp. 6790-6795 ◽  
Author(s):  
Zhigang Gai ◽  
Zhenxiang Cheng ◽  
Xiaolin Wang ◽  
Lanling Zhao ◽  
Na Yin ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Solid State ◽  
High Performance ◽  
Room Temperature ◽  
Dielectric Materials ◽  
Low Loss ◽  
Amorphous Tio2 ◽  
Colossal Dielectric Constant

High-performance dielectric materials continue to arouse considerable interest due to their application in the field of solid state capacitors.

Influence of Ti content and sintering temperature on dielectric properties of Bi4Ti3O12 ceramics

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744057 ◽  
Author(s):  
Yong Chen ◽  
Zhaozhi Li ◽  
Huyin Su ◽  
Simin Xue ◽  
Mengyun Bian ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Curie Temperature ◽  
Relative Permittivity ◽  
Dielectric Material ◽  
Perovskite Phase ◽  
Layered Perovskite ◽  
Microwave Ceramics ◽  
Ti Content

An ultra-broad working temperature dielectric material, Bi4Ti[Formula: see text]O[Formula: see text]([Formula: see text] = 2.96, 2.98, 3.0, 3.02 and 3.04), prepared by a conventional mixed oxide route was investigated which is supposed to replace lead-containing ceramics for its outstanding dielectric properties. Microstructure and dielectric properties of well-sintered samples (at 1040[Formula: see text]C, 1060[Formula: see text]C, 1080[Formula: see text]C, 1100[Formula: see text]C and 1120[Formula: see text]C) were studied. X-ray diffraction analysis indicated that the new material was in a single Bi-layered perovskite phase. The dielectric constant and dielectric loss at different frequencies (10, 100 and 1000 kHz) were measured at 1100[Formula: see text]C. With the increasing frequency, the dielectric constant decreased and the dielectric loss was almost unchanged. While at 100 kHz, there is the highest relative permittivity ([Formula: see text]) of 2822.8 and the lowest dielectric loss of 0.0040 ([Formula: see text] = 2.98), the Curie temperature ([Formula: see text]) is 668.9[Formula: see text]C. At the frequency of 1 MHz, the highest relative permittivity ([Formula: see text]) is 1115.8 when Ti content is 3.02, and the Curie temperature is 672.2[Formula: see text]C. SEM can explain the results of the dielectric spectrum at different Ti content and sintering temperatures. [Formula: see text] plots show that Bi4Ti3O[Formula: see text] ceramics are a kind of dielectrics. Since it possesses large dielectric constant, low dielectric loss and stable temperature character, this material shows promising applications for the ultra-broad temperature range components, such as high-temperature multilayer ceramic capacitors and microwave ceramics.

ChemInform Abstract: A Ferrimagnetic Manganese Oxide with a Layered Perovskite-Type Structure: YBaMn2O5.

ChemInform ◽  
2010 ◽  
Vol 28 (5) ◽  
pp. no-no
Author(s):  
J. P. CHAPMAN ◽  
J. P. ATTFIELD ◽  
M. MOLGG ◽  
C. M. FRIEND ◽  
T. P. BEALES
Keyword(s):  
Manganese Oxide ◽  
Type Structure ◽  
Layered Perovskite ◽  
Perovskite Type ◽  
Perovskite Type Structure

scholarly journals Nonstoichiometry Effects in SrTiO3 Ceramics Assessed by Transmission Electron Microscopy

2008 ◽  
Vol 14 (S3) ◽  
pp. 5-6 ◽  
Author(s):  
L. Amaral ◽  
A.M.R. Senos ◽  
P.M. Vilarinho
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Dielectric Permittivity ◽  
Grain Boundaries ◽  
Small Variation ◽  
Sintered Ceramic ◽  
Transmission Electron ◽  
Perovskite Type ◽  
Srtio3 Ceramics ◽  
Perovskite Type Structure

Strontium titanate (SrTiO3, ST) has a perovskite type structure that is cubic at room temperature, but transforms into a tetragonal one at 105K. At very low temperatures, ST exhibits an extremely large dielectric permittivity and piezoelectric and superconducting characteristics. ST finds applications in tunable microwave devices, due to a dependence of its dielectric response on the electric field and low microwave losses. ST electrical properties are strongly dependent on grain boundaries features and directly influenced by grain size distribution. It was found in our previous studies that a small variation in the stoichiometry of ST has a significant effect on the grain size of the sintered ceramic and related electrical properties: increased grain size and dielectric permittivity values have been reported for Ti excess compositions whereas Sr excess caused a decrease of grain size and of the dielectric permittivity. The tailoring of the dielectric properties by small non-stoichiometric variations in ST needs, however, a full understanding of its effects on the microstructure, phases structure and on the structure / composition of the grain boundaries.

Preparation and Dielectric Properties of Dy-B-Si-O Glass-Doped Ba0.6Sr0.4TiO3 Ceramics

2011 ◽  
Vol 418-420 ◽  
pp. 323-327
Author(s):  
Gui Shan Liu ◽  
Lan He Yang ◽  
Tie Cheng Ma ◽  
Kai Zhuo Wu ◽  
Zheng Jie Zhang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Sol Gel ◽  
Secondary Phase ◽  
Higher Temperature ◽  
Glass Additive ◽  
Bst Ceramics ◽  
Lower Temperature ◽  
Perovskite Type ◽  
Perovskite Type Structure

Dy-B-Si-O glass-doped Ba0.6Sr0.4TiO3 (BST) ceramics based on sol-gel-derived powders were prepared. Effects of B2O3-SiO2 in Dy-B-Si-O glass on phase structure, microstructures and dielectric properties of the BST ceramics were investigated. The results showed that the main crystal phase of BST ceramics with appropriate B2O3-SiO2 in Dy-B-Si-O glass had a perovskite type structure. Grain size decreased and density increased compared with pure BST ceramics. However, the secondary phase Ba2TiSi2O8 was detected when the percentage of B2O3-SiO2 in Dy-B-Si-O glass additive was over 7 mol%, and increased with the increasing of B2O3-SiO2. With the increasing of B2O3-SiO2, the dielectric constant increased firstly and then decreased, the dielectric loss decreased firstly and then increased, the Curie temperature moved to lower temperature firstly and then to higher temperature.

Preparation and electrical properties of Ni–Cu–Zn system doped with the magnesium oxide

2014 ◽  
Vol 28 (23) ◽  
pp. 1450157 ◽  
Author(s):  
O. M. Hemeda ◽  
A. Tawfik ◽  
D. M. Hemeda ◽  
A. M. Elsheekh
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Curie Temperature ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Lattice Parameter ◽  
Initial Permeability ◽  
Spectra Analysis ◽  
Cationic Distribution ◽  
Tan Δ

A sery of ferrite samples, Ni 0.1 Cu 0.2 Mg x Zn 0.7-x Fe 2 O 4, (x = 0.00, 0.15, 0.25, 0.35, 0.45, 0.55 and 0.70) have been prepared by the standard ceramic techniques, sintered at 1200°C for 2 h, and their crystalline structures were investigated by using X-ray diffraction, which confirmed the formation of Ni 0.1 Cu 0.2 Mg x Zn 0.7-x Fe 2 O 4 phase. The presence of Mg content increases the crystallinity of the given ferrite which is considered as catalyst for the accomplishment of the solid state reaction. The lattice parameter and crystallite size were calculated from XRD. The cationic distribution was estimated from the theoretical values of lattice parameters. The IR spectra analysis has been studied. The dielectric constant for the ferrite system Ni – Cu – Zn gradually increases with temperature up to nearly Curie temperature and then increase sharply beyond the Tc. The Curie temperature obtained from the [Formula: see text] versus T is in agreement with the Curie temperature obtained from other measurements. Dielectric loss tangent ( tan δ) has the same behavior as dielectric constant [Formula: see text]. A minimum value of dielectric loss tangent ( tan δ) for the system " Ni – Cu – Zn " was observed at x = 0.45. Magnetic permeability has been studied. The dependence of initial permeability on temperature exhibit a peak which is called Hopkinson peak (HP) in the vicinity of Curie temperature and confirmed the phase purity of ferrite sample. The increasing of porosity and decreasing of grain size play an important role in decreasing μi. It is clear that the value of Tc is found to increase by increasing the concentration of diamagnetic substitution Mg for " Ni – Cu – Zn " system.

Crystal growth of layered perovskite Sr2Nb2O7 and Sr2Ta2O7 film by the sol-gel technique

1999 ◽  
Vol 14 (3) ◽  
pp. 855-860 ◽  
Author(s):  
Kumi Okuwada ◽  
Shin-ichi Nakamura ◽  
Hiroshi Nozawa
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Dielectric Constant ◽  
Sol Gel ◽  
Small Variation ◽  
Layered Perovskite ◽  
Low Loss ◽  
Gel Technique ◽  
Lower Temperature ◽  
High Dielectric

High dielectric and low loss capacitor thin films of Sr2Nb2O7 (SN), Sr2Ta2O7 (ST), and their solid solution Sr2(Nbx, Ta1−x)2O7 (SNT) were investigated using the sol-gel technique. The SN film grows with the (0n0) orientation in the case of heating at over 700 °C. Heat treatment at a lower temperature results in the polycrystal ST-type structure. The SNT at x < 50% also resulted in the ST type. The dielectric constant for the SN film was 45, within 10% variation at ±0.5 MV/cm. Dielectric loss (tan δ) was 0.3–0.5%. The small variation in dielectric constant and the paraelectricity with low loss are suitable for capacitor applications.

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