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1.
Qingmeng Zhang Lei Wang Jun Luo Qun Tang Jun Du 《Journal of the American Ceramic Society》2009,92(8):1871-1873
The energy storage density of a Ba0.4 Sr0.6 TiO3 ceramic with the addition of 5–20 vol% glass was investigated. The results show that the improvement of the energy density in glass-added Ba0.4 Sr0.6 TiO3 samples arises due to two factors: one is that the breakdown strength is notably improved due to the decrease of the porosity and the reduction of the grain size and pore size in glass-added samples and the other is that the remnant polarization of glass-added samples is decreased. The energy density of the samples containing 5 vol% glass additive was improved by a factor of 2.4 compared with that of pure Ba0.4 Sr0.6 TiO3 . 相似文献
2.
A type of new low sintering temperature ceramic, Li2 TiO3 ceramic, has been found. Although it is difficult for the Li2 TiO3 compound to be sintered compactly at temperatures above 1000°C for the volatilization of Li2 O, dense Li2 TiO3 ceramics were obtained by conventional solid-state reaction method at the sintering temperature of 900°C with the addition of ZnO–B2 O3 frit. The sintering behavior and microwave dielectric properties of Li2 TiO3 ceramics with less ZnO–B2 O3 frit (≤3.0 wt%) doping were investigated. The addition of ZnO–B2 O3 frit can lower the sintering temperature of the Li2 TiO3 ceramics, but it does not apparently degrade the microwave dielectric properties of the Li2 TiO3 ceramics. Typically, the good microwave dielectric properties of ɛr =23.06, Q × f =32 275 GHz, τf = 35.79 ppm/°C were obtained for 2.5 wt% ZnO–B2 O3 frit-doped Li2 TiO3 ceramics sintered at 900°C for 2 h. The porosity was 0.08%. The Li2 TiO3 ceramic system may be a promising candidate for low-temperature cofired ceramics applications. 相似文献
3.
Barium strontium titanate is a promising material for microwave-phased array applications. 1,2 In this study, highly dense and fine-grained Ba0.6 Sr0.4 TiO3 ceramics were prepared using the spark plasma sintering (SPS) technique. The structure and dielectric tunable properties of the samples were investigated. The "distorted nano-region" emerged in the interior of the grains of SPS samples, and resulted in the deterioration of the dielectric tunable properties of Ba x Sr1− x TiO3 . This phenomenon indirectly testified to the assumption of the "polar nano-region" mechanism. After the SPS samples were annealed, the "distorted nano-region" disappeared and better dielectric tunable properties were obtained. The dielectric constant was decreased to 1048, and the K value (Commutation Quality Factor) reached 7089. 相似文献
4.
Minghui Zhang Hong Wang Feng Xiang Xi Yao 《International Journal of Applied Ceramic Technology》2009,6(2):257-263
(Ba0.6 Sr0.4 ) TiO3 thick films doped with glass slurry were fabricated by the screen-printing technique. The dielectric properties and the sintering mechanism were investigated. The films can be sintered at 600°C. The dielectric constant is 88 and the dielectric loss is 0.002 with a tunability of 23.86% under 100 kV/cm. Higher dielectric constant and tunability were obtained in the samples sintered at higher temperatures. The highest tunability is 61.12% under 150 kV/cm in the sample sintered at 800°C. The low sintering temperature and dielectric loss of the glass-doped thick films make them potential candidates for LTCC and microwave tunable devices. 相似文献
5.
The formation of BaTiO3 from equimolar BaCO3 and TiO2 (rutile) mixtures was studied in air and in CO2 . A small amount of BaTiO3 is formed first directly from BaCO3 and TiO2 at the surface of contact. From then on it is a diffusion-controlled reaction, and both BaTiO3 and Ba2 TiO4 are produced, with Ba2 TiO4 being formed in much larger amounts. In 1 atmosphere of CO2 , the intermediate Ba2 TiO4 was suppressed up to a temperature of about 1100°C. in agreement with thermodynamic calculations. Ba2 TiO4 reacts fast with 1 atmosphere of CO2 below about 1100°C. to produce BaTiO3 and BaCO3 相似文献
6.
Sung Min Rhim Heungjin Bak Seokmin Hong Ok Kyung Kim 《Journal of the American Ceramic Society》2000,83(12):3009-3013
The effects of heating rate on the sintering behavior and the dielectric properties of Ba0.7 Sr0.3 TiO3 ceramics prepared by boron-containing liquid-phase sintering were investigated. When 0.5 wt% B2 O3 was added to Ba0.7 Sr0.3 TiO3 , sintering was achieved at ∼1150°C, and the overdoped B2 O3 did not form an adequate amount of liquid phase or volatilize; it remained in the samples and formed a secondary phase. A transition broadening was observed as the heating rate increased. As the heating rate increased, the Curie temperature increased and the maximum dielectric constant ( k max ) at the Curie temperature decreased. This result is attributable to a decrease in the diffuseness parameter (δ) and the tetragonality ( c / a ). 相似文献
7.
Jian-Gong Cheng Jun Tang Xiang-Jian Meng Shao-Ling Guo Jun-Hao Chu Min Wang Hong Wang Zhuo Wang 《Journal of the American Ceramic Society》2001,84(7):1421-1424
A sol-gel process was used to prepare pyroelectric Ba0.8 Sr0.2 TiO3 thin films with large columnar grains (100–200 nm in diameter) on Pt/Ti/SiO2 /Si substrates, via using a 0.05 M solution precursor. The relationship between dielectric constant and temperature (ɛr - T ) showed two distinctive phase transitions in the Ba0.8 Sr0.2 TiO3 thin films. Both the remnant polarization and the coercive field decreased as the temperature increased from −73°C to 40°C. Its low dissipation factor (tan δ= 2.6%) and high pyroelectric coefficient ( p = 4.6 × 10−4 C·(m2 ·K)−1 at 33°C), together with its good insulating properties, made the prepared Ba0.8 Sr0.2 TiO3 thin films promising for use in uncooled infrared detectors and thermal imaging applications. 相似文献
8.
Compatible phases in the system Li2 O-Al2 O3 -TiO2 at various temperature levels were determined mainly by solid-state reactions for the portion of the ternary system bounded by Li2 O Al2 O2 , Li2 O.TiO2 , Al2 O, and TiO2 . The existence of a ternary compound, Li2 O.Al2 O3 .4TiO2 , and nine joins was established. The ternary compound has a lower limit of stability at 1090°± 15°C. and dissociates and recombines rapidly at 1380°± 15°C. 相似文献
9.
The electrical properties of Sr0.5 Ba0.3 TiO3 in the presence of Nb2 O5 as a donor, 3Li2 O · 2SiO2 as a sintering agent, and Bi2 O3 as a dopant have been studied. When the compositions of the ceramics were 1 mol Sr0.7 Ba0.3 TiO3 + 0.5 mol% Nb2 O5 + 2 mol% 3Li2 O · 2SiO2 + 0.2 mol% Bi2 O3 , the ceramics were sintered at 1100°C and exhibited the following characteristics: apparent dielectric constant ɛ, 25000; loss factor tan δ, 2%; insulating resistivity ρj , 1010 Ω· cm; variation of dielectric constant with temperature Δɛ/ɛ (−25° to +85°C), +10%, −14%. ɛ and tan δ show only small changes with frequency. The study shows this ceramic can be used in multilayer technology. 相似文献
10.
Bonnie L. Gersten Malgorzata M. Lencka Richard E. Riman 《Journal of the American Ceramic Society》2004,87(11):2025-2032
A thermodynamic model was developed to describe the stability of (Ba,Sr)TiO3 (BST) solid solutions in the Ba–Sr–Ti–K–(EDTA)–H2 O (EDTA = ethylenediaminetetraacetic acid) system. Phase diagrams were computed to identify the range of conditions suitable for making phase-pure BST. Hydrothermal experiments were performed to validate the thermodynamic model. The model was found to be more useful when an ideal solid solution was used to estimate the energetics for the BST phase instead of experimental thermodynamic data. In addition, EDTA was found to promote stable conditions for BST formation. When attempting to prepare Ba0.50 Sr0.50 TiO3 without EDTA, BaTiO3 -rich and SrTiO3 -rich phases precipitated separately, at 70°–160°C. However, in the presence of EDTA, a phase-pure Ba 0.55 Sr0.45 TiO3 solid solution was obtained at 90°–120°C. EDTA is effective because it prevents phase heterogeneities from forming and equalizes the adsorption affinity of strontium and barium species. 相似文献
11.
Sung Min Rhim Seokmin Hong Heungjin Bak Ok Kyung Kim 《Journal of the American Ceramic Society》2000,83(5):1145-1148
The effects of B2 O3 addition on the sintering behavior and the dielectric and ferroelectric properties of Ba0.7 Sr0.3 TiO3 (BST) ceramics were investigated. The dielectric and ferroelectric properties of a BST sample with 0.5 wt% B2 O3 sintered at <1150°C were as good as those of undoped BST sintered at 1350°C, and the dielectric loss was better. When >1.0 wt% B2 O3 was added to BST, the overdoped B2 O3 did not form a liquid phase or volatilize; it remained in the samples and formed a secondary phase that lowered the sintering behavior and the dielectric and ferroelectric properties of the BST. 相似文献
12.
Direct-Current Field Dependence of Dielectric Properties in Alumina-Doped Barium Strontium Titanate 总被引:7,自引:0,他引:7
Long Wu Yih-Chien Chen Cheng-Liang Huang Yi-Ping Chou Yuan-Tu Tsai 《Journal of the American Ceramic Society》2000,83(7):1713-1719
The dielectric properties of (Ba0.6 Sr0.4 )TiO3 and Al2 O3 -doped (Ba0.6 Sr0.4 )TiO3 have been characterized. The grain size of the specimen is maximum for (Ba0.6 Sr0.4 )TiO3 that has been doped with 1 wt% Al2 O3 . The density and the real part of the relative dielectric constant each decrease as the Al2 O3 content increases. The loss factor is minimum for (Ba0.6 Sr0.4 )TiO3 that has been doped with 2 wt% Al2 O3 . The dielectric constant of the specimens decreases as the applied dc field increases. The influence of the dc field on the loss factor is much less than that on the dielectric constant. The tunability is ∼24% for (Ba0.6 Sr0.4 )TiO3 that has been doped with 1 wt% Al2 O3 . 相似文献
13.
Jenn-Ming Wu Ming-Chu Chang Pei-Chih Yao 《Journal of the American Ceramic Society》1990,73(6):1599-1605
The reaction sequence of 0.15(Ba0.95 Sr0.05 )O· 0.15Sm2 O3 · 0.7TiO2 ceramics during heating as well as the effects of calcination and sintering on microwave properties were investigated. Quantitative microscopic analysis was performed to obtain the volume fraction of the phases. It was found that the amount of second phase, especially TiO2 (rutile), greatly affected the temperature coefficient of resonant frequency of the ceramics. The higher the amount of TiO2 phase, the more positive or the less negative the temperature coefficient of resonant frequency. The temperature coefficient of BaO · Sm2 O3 · 5TiO2 was calculated using the logarithmic mixing rule to be −30 ppm/°C. The volume fractions of the phases varied with conditions of calcination and sintering. Therefore, by varying calcination and/or sintering temperature, the temperature coefficient of resonant frequency could be adjusted to nearly zero. 相似文献
14.
Chun-Hsu Shen Cheng-Liang Huang Chuan-Feng Shih Chih-Ming Huang 《International Journal of Applied Ceramic Technology》2009,6(5):562-570
The microstructure and microwave dielectric properties of a (1− x )(Mg0.95 Ni0.05 )TiO3 − x Ca0.6 La0.8/3 TiO3 ceramics system have been investigated. The system was prepared using a conventional solid-state ceramic route. In order to produce a temperature-stable material, Ca0.6 La0.8/3 TiO3 was added for a near-zero temperature coefficient (τf ). With partial replacement of Mg2+ by Ni2+ , the dielectric properties of the (1− x )(Mg0.95 Ni0.05 )TiO3 − x Ca0.6 La0.8/3 TiO3 ceramics can be promoted. The microwave dielectric properties are strongly correlated with the sintering temperature and the composition. An excellent Q × f value of 118,000 GHz can be obtained for the system with x =0.9 at 1325°C. For practical application, a dielectric constant (ɛr ) of 24.61, a Q × f value of 102,000 GHz, and a temperature coefficient of resonant frequency (τf ) of −3.6 ppm/°C for 0.85(Mg0.95 Ni0.05 )TiO3 −0.15Ca0.6 La0.8/3 TiO3 at 1325°C are proposed. A parallel-coupled line band-pass filter is designed and simulated using the proposed dielectric to study its performance. 相似文献
15.
Qun Zeng Wei Li Jian-lin Shi Xian-lin Dong Jing-kun Guo 《Journal of the American Ceramic Society》2008,91(2):644-647
A group of new y M-phase/(1− y ) Li2+ x Ti1−4 x Nb3 x O3 composite ceramics with adjustable permittivities for low-temperature co-fired ceramic applications was initially investigated in the study. The 0.5 M-phase/0.5 Li2+ x Ti1−4 x Nb3 x O3 ( x =0.01, 0.02, 0.04, 0.06, 0.081) composite ceramics were first investigated to find the appropriate "Li2 TiO3 ss" composition ( x value). The best dielectric properties of ɛr =40.1, Q × f values up to 9318 GHz, τf =25 ppm/°C, were obtained for the ceramics composites at x =0.02. Based on the good dielectric properties, the suitable "Li2 TiO3 ss" composition with x =0.02 was mixed with the Li1.0 Nb0.6 Ti0.5 O3 powder as the ratio of y "M-phase"/(1− y ) "Li2 TiO3 ss" ( y =0.2, 0.4, 0.5, 0.6, 0.8). By adjusting the y values, the group of composite ceramics could exhibit largely are adjustable permittivities varying from ∼20 to ∼60, while Q × f and τf values relatively good. Nevertheless, in this study, because there are interactions between the M-phase and Li2 TiO3 ss during sintering process, their microwave dielectric properties could not be predicted precisely by the empirical model. 相似文献
16.
Haitao Jiang Jiwei Zhai Jingji Zhang Xi Yao 《Journal of the American Ceramic Society》2009,92(10):2319-2322
In the present work, the sintering behaviors and dielectric properties of Ba0.60 Sr0.40 TiO3 (BST) ceramics with the addition of BaCu(B2 O5 ) were investigated in detail. The results indicated that the addition reduced the sintering temperature of BST by about 500°C. It was suggested that a liquid phase BaCu(B2 O5 ) assisted the densification of BST ceramics at lower temperatures. For a low-level BaCu(B2 O5 ) addition (2.0 mol%), the BST sample sintered at 950°C for 5 h displayed good dielectric properties, with a moderate dielectric constant (ɛ=2553) and a low dielectric loss (tan δ=0.00305) at room temperature and at 10 kHz. The sample showed 45.9% tunability at 10 kHz under a dc electric field of 30 kV/cm. At the frequency of 0.984 GHz, BST-added 2.0 mol% BaCu(B2 O5 ) possessed a dielectric constant of 2204 and a Q value of 146.7. 相似文献
17.
Bh. V. JANAKIRAMA RAO 《Journal of the American Ceramic Society》1964,47(9):455-463
Glasses corresponding to mole formulas R2 TiO3 and R2 Ti2 O5 were prepared in 1- to 5-g quantities by quenching in a platinum crucible. K2 O, Rb2 O, and Cs2 O formed fairly stable glasses with TiO2 . On heat treatment, these glasses nucleated readily and formed opal-like glasses. Li2 O and Na2 O, however, did not form glasses with TiO2 in 1-g quantities. Hygroscopicity increased with the alkali content and decreased with the increase in TiO2 concentration. The refractive indices of the glasses ranged from 1.66 to 1.90. These facts indicate that TiO2 is a glass former in its own right and that Ti4+ exists in sixfold coordination in these glasses. 相似文献
18.
Jing L. Shang Gujin Hu Ting Zhang Yan Sun Jie Wu Jun H. Chu Ning Dai 《Journal of the American Ceramic Society》2009,92(9):2159-2161
Herein we report on a simple, low cost, and feasible route for the construction of PbZr0.4 Ti0.6 O3 (PZT)- or Ba0.9 Sr0.1 TiO3 (BST)-based optical microcavities using a single chemical solution containing polymer polyvinylpyrrolidone. The obtained multilayer systems not only exhibit good ferroelectric performance, but also display well-defined resonant modes with a quality factor of no <66. Compared with PZT microcavities, the optical properties of the BST microcavities appear to be superior. 相似文献
19.
Vidya S. Tiwari Neelam Singh Dhananjai Pandey 《Journal of the American Ceramic Society》1994,77(7):1813-1818
Ba1–x Cax TiO3 powders have been prepared using a novel route involving solid-state reaction in a mixture of Ba1–x Cax CO3 and TiO2 . The Ba1–x Cax CO3 precursors used in this method were prepared by a chemical coprecipitation route to ensure a uniform supply of Ba and Ca ions during thermochemical reaction with TiO2 . The compositional homogeneity of Ba1–x Cax TiO3 powder prepared by such a semiwet route is compared with those prepared by the conventional dry route, involving thermochemical reaction in a mixture of BaCO3 , CaCO3 , and TiO2 , using principles of X-ray line broadening. It is shown that the powders obtained by the semiwet route possess better compositional homogeneity, over a length scale of 1800 Å corresponding to the coherently scattering domain size, than those prepared by the conventional dry route. Microstructural studies have revealed grain sizes of the order of 1 μm and several micrometers, respectively, for ceramics prepared by the semiwet and conventional dry routes. The solid solubility limit of Ca in Ba1–x Cax TiO3 ceramics fired at 1300°C is 16 mol% for samples prepared by the semiwet route while conventionally processed ceramics had a Ca solid Solubility limit of 12 mol% at the same temperature. 相似文献
20.
Microstructure–Dielectric Properties Relationship in Ba0.6 Sr0.4 TiO3 –Mg2 SiO4 –Al2 O3 Composite Ceramics
Ying Chen Yuan-Yuan Zhang Xian-Lin Dong Gen-Shui Wang Fei Cao 《Journal of the American Ceramic Society》2010,93(1):161-166
0.60Ba0.6 Sr0.4 TiO3 (BST)–(0.40− x )Mg2 SiO4 (MS)– x Al2 O3 ( x =0, 0.5, 3, 5wt%) composite ceramics exhibit excellent characteristics suitable for tunable device applications. With increasing amount of Al, the dielectric peak can be quantitatively broadened and suppressed; the "phase transition temperature" T c or ( T m ) shifts to a lower temperature. Meanwhile, the tunability is still high in a wider temperature range. Far from T c , pyroelectric effects are observed by using the Byer and Roundy technology and Slim polarization hysteresis loops are observed under high ac dielectric field at 10Hz. These proved the existence of spontaneous polarization in certain possible orientations in a broad temperature range above T c in the paraelectric medium and reveal why 0.60BST–(0.40− x )MS– x Al2 O3 have such remarkable dielectric nonlinearity. 相似文献