共查询到20条相似文献,搜索用时 15 毫秒
1.
K. W. Bennett P. S. Brody B. J. Rod L. P. Cook P. K. Schenck 《Integrated ferroelectrics》2013,141(2):191-205
Abstract Switched remanent polarization was measured as a function of accumulated switching cycles for a variety of ferroelectric films using sinusoidally driven hysteresis loops. Switched remanent polarization and dielectric constant and loss were also obtained as a function of the cycling frequency. PZT films with niobium additives appeared to lose switched remanent polarization with accumulated cycles at a lesser rate than films without niobium. The switched remanent polarization was found to decrease with increasing frequency, which we attribute to the effect of grain size. Also, a decrease of dielectric constant with increasing frequency and an increase of dielectric constant with increased applied voltage are attributed to the effects of domain wall motion contributions to dielectric constant. 相似文献
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Satoshi Wada Hiroaki Yasuno Takuya Hoshina Hirofumi Kakemoto Yoshikazu Kameshima Takaaki Tsurumi 《Journal of Electroceramics》2008,21(1-4):198-201
Barium titanate (BaTiO3) crystallites with various particle sizes from 22 to 500 nm were prepared by the two-step thermal decomposition method of barium titanyl oxalate. Various characterizations revealed that these particles were impurity-free, defect-free, dense BaTiO3 particles. The powder dielectric measurement clarified that the dielectric constant of BaTiO3 particles with a size of around 58 nm exhibited a maximum of over 15,000. To explain this size dependence, the THz region dielectric properties of BaTiO3 fine particles, especially Slater mode frequency, were measured using the far infrared (FIR) reflection method. As the result, the lowest Slater mode frequency was obtained at 58 nm. This tendency was completely consistent with particle size dependence of the dielectric constant. 相似文献
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Ba x Sr1-x TiO3, nanoparticles with different Ba compositions were synthesized by a hydrothermal method. The mechanism of hydrothermal reactions was discussed based on DTA/TG, XRD and TEM characterizations. The result showed that perovskite structure was developed through the mutual diffusion between the intermediate phases and TiO2 phase. The grain size of the Ba0.77Sr0.23TiO3 (BST77) powders was about 20–40 nm. BST ceramics were made from the hydrothermal-derived BST powders and the dielectric properties of the BST ceramics were measured. Due to the small grain size and active surface energy of the BST powders prepared by hydrothermal method, the BST ceramics showed low sintering temperature. It was found that the BST77 ceramics sintered at 1280 °C showed dielectric constant peak dispersion which was believed to be caused by dimension domino effect. 相似文献
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The effect of dysprosium (Dy) doping on the structural and dielectric properties of barium titanate (BaTiO3) ceramic has been studied. Dysprosium-doped barium titanate (BT) with general formula Ba1-xDy2x/3TiO3 (x?=?0.0–0.1) is prepared through solid state reaction route. The XRD pattern reports the single phase tetragonal structure up to x?=?0.025 with space group of P4mm and a secondary phase is observed for higher concentration of Dy. The Raman study of Ba1-xDy2x/3TiO3 (x?=?0.00, 0.01, 0.025) also reveals that the ceramic is showing tetragonal symmetry and with an increase in Dy doping the tetragonal phase is moving toward more symmetric phase i.e. cubic pm3m. The surface morphology of the sintered pellets shows a compact and homogeneous grain distribution with a decrease in grain size as the Dy content increases. The temperature and frequency dependency dielectric study of the ceramic compositions (x?=?0.00, 0.01, 0.025) are studied to show the effect of Dy ion on the A site of BaTiO3 perovskite ceramic. The dielectric constant decreases with increase in Dy content. The dielectric diffusivity increases with increase in doping concentration. The P-E hysteresis loop confirms the ferroelectric behavior of the sample with decrease in remanent polarization and increase in coercive field. 相似文献
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In this paper we try to do systematic investigation on the structure and dielectric properties of low temperature sintered barium titanate based X7R ceramics, which are doped with rare earth oxide, Nb2O5, Co3O4 using ZnO–B2O3 as the sintering aids. The dielectric ceramic powder can be sintered at the temperature below 950°C to satisfy X7R requirement and also with good permittivity and low dielectric loss. The research strongly suggest that this doped BaTiO3 based ceramic, which can be sintered at a rather low temperature, may be used in the production of MLCC with low content of Pd in the Ag–Pd electrode, and for sure, the production cost would be greatly reduced. 相似文献
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Nd-doped bismuth titanate Bi4 − x
Nd
x
Ti3O12 ceramics (x = 0–1.0) were prepared by the solid state reaction method. The temperature dependence of the dielectric dispersion and ferroelectric
properties were investigated. With the increase of the Nd substitution for Bi ion, the Curie temperature decreased and the
corresponding dielectric constant peak broadened. In addition, the strong low-frequency dielectric dispersions were exhibited.
The Nd doping decreases the temperature dependence of the ac conductivity and increases the temperature dependence of the
remanent polarization, which is caused by the induced polarization by defects, such as bismuth and oxygen vacancies. 相似文献
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K. Pengpat S. Hanphimol S. Eitssayeam U. Intatha G. Rujijanagul T. Tunkasiri 《Journal of Electroceramics》2006,16(4):301-305
The important properties of lead-free piezoelectric ceramics have been investigated from Bismuth Sodium Lanthanum Titanate
and Barium Titanate system: (1 − y)(Bi0.5Na0.5)(1 − 1.5x)La
x
TiO3(BNLT)—yBaTiO3(BT) where x = 0.017 and y = 0 − 0.2, respectively. The morphotropic phase boundary (MPB) was found to be around y = 0.1 by the x-ray diffraction and dielectric measurement at various amount of BT. The temperature dependence of dielectric
constant (ε
r
) at various value of y showed the diffuse phase transition exhibiting the relaxor type ferroelectrics. The degree of diffuseness
increased at a high doping content of about y = 0.15 where the second phase transition (T2) of the ferroelectric to antiferroelectric phase disappeared. Moreover, this sample had the maximum piezoelectric coefficient
(d
33) of about 112 pC/N with relatively low dielectric constant. The optimum sintering temperatures and the microstructures of
the dense BNLT-BT ceramics were also examined. 相似文献
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Bismuth titanate (BiT) based composites containing silver particles are fabricated by a solution chemical process. Incorporation
of silver particles does not result in unwanted reaction phase. SEM micrographs reveal fine silver particles distribute at
BiT grain boundaries and into larger BiT plate-like grains. With the addition of silver, the dielectric constant increases
up to ∼10 times higher than that of pure BiT ceramic, which can be attributed to the effective electric fields developed around
the dispersed metal particles and the percolation effect. Additionally, the dielectric losses are significantly reduced by
incorporating silver particles, and the values of BiT/Ag composites are lower than 0.5%. The dielectric properties of BiT/Ag
composites are nearly frequency independent in the measured frequency range (1 kHz to 1 MHz). 相似文献
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AbstractDielectric properties of nanocrystalline barium zirconate titanate (Ba(ZrxTi1-x)O3; BZT for x?=?0.1 and 0.3) synthesized by glycine-nitrate autocombustion method were investigated in this study. The phase formation examined by TGA-DTA, XRD, FT-IR and Raman spectroscopy confirmed that high purity single-phase BZT with perovskite structure was obtained by using glycine-to-nitrate molar ratio of 2.2:4 and calcining in air at 1100?°C for 4?h. TEM analysis showed that BZT had agglomerate particles consisted of primary spherical nanocrystals with the size of 8-11?nm. The diffuse phase transition behavior of BZT ceramics increased with increasing Zr concentration and for x?=?0.3, the Curie temperature; Tc, shifted to below room temperature. The BZT ceramics for x?=?0.1 had relatively high dielectric constant (ε), 13007, low Tc, 76?°C and comparable dielectric loss (tan δ) at Tc, 0.012 which caused by the high degree of Zr diffuseness into the perovskite structure. These results suggest that glycine-nitrate autocombustion is the effective method for preparing high quality BZT ceramics. 相似文献
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Chanisa Nawanil Worawut Makcharoen Krittanat Khaosa-Ard Tosapol Maluangnont Wanwilai Vittayakorn Don Isarakorn 《组合铁电体》2019,195(1):46-57
AbstractThis study explored the preparation and electrical properties of 0–3 barium titanate/polydimethylsiloxane nanocomposites by dispersing barium titanate nanoparticles (BaTiO3; BT) into the polydimethylsiloxane (PDMS) matrix phase. The effect of barium titanate nanoparticles on electrical properties has been investigated systematically, and the relative permittivity of nanocomposites was found to increase significantly with increasing barium titanate content. Different theoretical models were used to predict the dielectric constant of these composites and compare their experimental value with the theoretical value in order to find an appropriate equation. The result indicated that the dielectric properties of composites are influenced not only by relative permittivity of the components but also dependence on interactions between ceramics and polymers. Furthermore, the preparation and dielectric properties of BT/PDMS nanocomposites modified with carbon nanotube (CNT) were also studied. The dielectric results demonstrate that adding CNT can enhance the relative permittivity of the BT/PDMS composite via improvement of dispersion and distribution of the BT nanoparticles in the PDMS matrix phase. Moreover, the electrical outputs from the BT/PDMS/CNT nanocomposites generator were measured under periodic knocking. The nanocomposites innovatively expand the feasibility of self-powered energy systems for smart sensor and energy harvesting applications. 相似文献
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Hu Qi Tang Jiayuan Teng Yuancheng Zhao Xiaofeng Arslanov Temirlan Ahuja Rajeev 《Journal of Electroceramics》2022,48(3):117-126
Journal of Electroceramics - CaCu3Ti4O12 ceramics have great dielectric constant, excellent temperature stability and good frequency stability. However, due to high dielectric loss, its practical... 相似文献
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M. H. Badr L. M. Sharaf El-Deen A. H. Khafagy D. U. Nassar 《Journal of Electroceramics》2011,27(3-4):189-196
Ba(1-x)Sr(x)TiO3 ceramics, where x?=?0.05, 0.10, 0.15, and 0.20, were prepared by solid state reaction technique. X-ray diffraction analysis confirmed the formation of single phase perovskite structures. Mechanical properties such as ultrasonic attenuation, longitudinal wave velocity, and longitudinal elastic modulus were studied by an ultrasonic pulse echo technique at 2 MHz. Investigations of ceramic microstructures and mechanical properties showed its dependence on composition and sintering time. Increasing of Sr content, x, resulted in a decrease in bulk density and ultrasonic attenuation and an increase in velocity and modulus. Also, size of crystallites and c/a ratio were found to decrease with increasing of x, and increased with increasing of sintering time. High temperature ultrasonic studies showed, in addition to Curie phase transition, two relaxation peaks and its origin was investigated. The acquired structural and mechanical results were correlated and discussed. 相似文献
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Barium titanate (BaTiO3) can form solid solution with many oxides. The present study demonstrates that BaTiO3 can also dissolve a small amount of Ag during co-firing, and its solubility depends strongly on the Ba/Ti ratio. A solid-state reaction was employed in the present study to prepare the BaTiO3 powders with Ba/Ti ratio varied from 0.991 to 1.010. Fine Ag particles were then mixed intimately with the non-stoichiometric BaTiO3 powders. The solubility of Ag in the non-stoichiometric BaTiO3 at 1,350 and 1,390 °C was then determined by using a modified electron-probe micro-analysis (EPMA) technique. The solubility of Ag in Ti-rich BaTiO3 is nearly double that in Ba-rich BaTiO3. The diffusion distance of Ag in the non-stoichiometric BaTiO3 is longer than 5 μm. 相似文献
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A new patterning method combining electron beam (EB) lithography and electrophoretic deposition (EPD) for fabricating micropatterned barium titanate (BaTiO3) thin films was investigated. At first, resist molds with high resolution were prepared using EB lithography on Pt/Ti/Si substrates. Then BaTiO3 nanoparticles were deposited on the substrates by EPD from a transparent suspension of monodispersed BaTiO3 nanoparticles; a mixed solvent of 2-methoxyethonal and acetylacetone with a 9:1 volumetric ratio was used as a dispersion medium. The nanoparticles with an average size of about 10 nm were synthesized at a low temperature of 90 °C by a high concentration sol-gel process. EPD layers superfluously deposited on the resist molds were mechanically polished away, followed by chemically removing the molds in a resist remover to leave micropatterns of BaTiO3 nanoparticles on the substrates, which were finally sintered to yield micropatterned BaTiO3 ceramic thin films. The method developed may be used to fabricate other micropatterned electroceramic thin films. 相似文献
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Jinho Kim Seongjin Hwang Wookyung Sung Hyungsun Kim 《Journal of Electroceramics》2009,23(2-4):209-213
To develop a low dielectric constant of LTCC substrate, we studied the effect of the sintering and crystallization behavior on the dielectric properties of a sintered body by mixing a CaO–Al2O3–SiO2 frit and a CaO–MgO–SiO2 frit for a low dielectric constant of LTCC substrates. In this work, the two glass frits were mixed at different proportions and sintered at 860~920°C. After sintering at 900oC for 1h, the glass frits crystallized into diopside and anorthite. The sintered bodies exhibited dielectric properties, ? r?=?6~8.6 at 1 GHz, which is an essential condition for a substrate in microwave devices. The results suggest that the glass-ceramic can be applied to low dielectric LTCC materials in the electronics packaging industry. 相似文献