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1.
Microwave Dielectric Properties of LiKSm2(MoO4)4 Ceramics with Ultralow Sintering Temperatures
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Xiao‐Liu Zhai Xu Zheng Hai‐Hong Xi Wen‐Bo Li Jun Han Di Zhou 《Journal of the American Ceramic Society》2015,98(9):2716-2719
In this work, a novel low‐temperature firing microwave dielectric ceramic LiKSm2(MoO4)4 was prepared via solid‐state reaction method. Ceramic samples with relative densities about 94.6% were obtained at sintering temperature 640°C–680°C. The best microwave dielectric properties was obtained in ceramic sample sintered at 620°C with a permittivity about 11.5, a Q × f value about 39 000 GHz and a temperature coefficient of frequency about ?15.9 ppm/°C. According to XRD patterns and backscattered electron micrograph, combined with Energy Dispersive Spectra analysis, of cofired samples with 30 wt% aluminum sintered at 620°C/4 h, the LiKSm2(MoO4)4 ceramic was found to be chemically compatible with Al but react seriously with Ag, forming AgSmMo2O8 phase, at its sintering temperature. 相似文献
2.
Yang Wang Ruzhong Zuo Chen Zhang Jian Zhang Tianwen Zhang 《Journal of the American Ceramic Society》2015,98(1):1-4
We report a series of ReVO4 (Re = La, Ce) microwave dielectric ceramics fabricated by a standard solid‐state reaction method. X‐ray diffraction and scanning electron microscopy measurements were performed to explore the phase purity, sintering behavior, and microstructure. The analysis revealed that pure and dense monoclinic LaVO4 ceramics with a monazite structure and tetragonal CeVO4 ceramics with a zircon structure could be obtained in their respective sintering temperature range. Furthermore, LaVO4 and CeVO4 ceramics sintered at 850°C and 950°C for 4 h possessed out‐bound microwave dielectric properties: εr = 14.2, Q × f = 48197 GHz, τf = ?37.9 ppm/°C, and εr = 12.3, Q × f = 41 460 GHz, τf = ?34.4 ppm/°C, respectively. The overall results suggest that the ReVO4 ceramics could be promising materials for low‐temperature‐cofired ceramic technology. 相似文献
3.
Congxue Su Weishuang Fang Zhenhai Wei Ying Tang Liang Fang 《Journal of the American Ceramic Society》2014,97(12):3740-3743
Microwave dielectric properties of Li‐containing orthorhombic compounds with the composition of MLi2Ti6O14 (M = Ba and Sr) were investigated. The ceramics were synthesized by the conventional solid‐state reaction route. The optimized sintering temperatures for the BaLi2Ti6O14 and SrLi2Ti6O14 ceramics are 1025°C and 1000°C, respectively. Favorable microwave dielectric properties were obtained with moderate εr of 31.7 and 33.6, quality factor Q × f values of 23 300 (at 7.3 GHz) and 8700 GHz (at 6.8 GHz), and low‐temperature coefficient of resonant frequency (τf) values of ?15.4 and ?2.7 ppm/°C for BaLi2Ti6O14 and SrLi2Ti6O14 ceramics, respectively. The addition of BaCu(B2O5) can effectively reduce the sintering temperature below 930°C without degrading the microwave dielectric properties. Compatibility with Ag electrode indicates these materials could be applied to low‐temperature cofired ceramic devices. 相似文献
4.
Yang Lv Ruzhong Zuo Ying Cheng Chen Zhang 《Journal of the American Ceramic Society》2013,96(12):3862-3867
The novel low‐temperature sinterable (1 ? x)Ba3(VO4)2–xLiMg0.9Zn0.1PO4 microwave dielectric ceramics were prepared by cofiring the mixtures of pure‐phase Ba3(VO4)2 and LiMg0.9Zn0.1PO4. The phase structure and grain morphology of the ceramics were evaluated using X‐ray diffraction, Raman spectra, and scanning electron microscopy. The results indicated that Ba3(VO4)2 and LiMg0.9Zn0.1PO4 phases can well coexist in the sintered body. Nevertheless, a small amount of LiZnPO4 and some vanadate phases with low melting points were observed, which not only can influence the microwave dielectric properties of the ceramic but also can obviously improve the densification behavior at a relatively low sintering temperature. The near‐zero temperature coefficients of the resonant frequency (τf) could be achieved by adjusting the relative content of the two phases owing to their opposite τf values and simultaneously a desirable quality factor Q × f value can be maintained. No chemical reaction between the matrix ceramic phase and Ag took place after sintering at 800°C for 4 h. The ceramics with 45 vol% LiMg0.9Zn0.1PO4 can be well sintered at only 800°C and exhibit excellent microwave dielectric properties of εr ~ 10, Q × f ~ 64 500 GHz, and τf ~ ?2.1 ppm/°C, thus showing a great potential as a low‐permittivity low‐temperature cofired microwave dielectric material. 相似文献
5.
Liang Fang Zhenhai Wei Wei Liao Huanfu Zhou Hui Zhang Fei Xiang 《Journal of the American Ceramic Society》2014,97(2):498-500
A new Li‐containing microwave ceramic Ba5Li2W3O15 with hexagonal perovskite structure was prepared through a solid‐state ceramic route. Small amount of scheelite BaWO4 appeared as a second phase during sintering. The Ba5Li2W3O15 could be well densified at 1120°C and exhibits good microwave dielectric properties with permittivity (εr) of 25.4, high Q × f value about 39 000 GHz, and low temperature coefficient of resonate frequency (τf) of 10 ppm/°C. The addition of BaCu(B2O5) can effectively lower the sintering temperature from 1120°C to 900°C and does not induce degradation of the microwave dielectric properties. These results indicate that the Ba5Li2W3O15 ceramic might be a promising candidate in microwave dielectric resonators. 相似文献
6.
A Novel Low‐Firing and Low Loss Microwave Dielectric Ceramic Li2Mg2W2O9 with Corundum Structure
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Huanhuan Guo Liang Fang Xuewen Jiang Jie Li Fengqi Lu Chunchun Li 《Journal of the American Ceramic Society》2015,98(12):3863-3868
The crystal structure and microwave dielectric properties of a novel low‐firing compound Li2Mg2W2O9 were investigated in this study. The phase purity and crystal structure were investigated using X‐ray diffraction analyses and Rietveld refinement. The best microwave dielectric properties of the ceramic with a low permittivity (εr) ~11.5, a quality factor (Q × f) ~31 900 GHz (at 10.76 GHz) and a temperature coefficient of the resonant frequency (τf) ~ ?66.0 ppm/°C were obtained at the optimum sintering temperature (920°C). CaTiO3 was added into the Li2Mg2W2O9 ceramic to obtain a near zero τf, and 0.93Li2Mg2W2O9–0.07CaTiO3 ceramic exhibited improved microwave dielectric properties with a near‐zero τf ~ ?1.3 ppm/°C, a εr ~21.6, a high Qu × f value ~20 657 GHz. The low sintering temperature and favorable microwave dielectric properties make it a promising candidate for LTCC applications. 相似文献
7.
《Ceramics International》2020,46(14):22460-22465
Borates are promising candidates as dielectric substrate materials in low temperature cofired ceramics technology (LTCC) due to their relative low sintering temperatures and relative permittivities compared to their counterparts. However, synthesizing borates having single-phase is still challenging because of the volatility and hydrophilicity of boron resources. In this work, a compositional design was utilized to synthesize single-phase LiBGeO4 ceramics over a broad temperature range from 600 to 840 °C. Radio-frequency dielectric behaviours featured a strong temperature dependence, especially at high temperatures (>400 °C), which is related to the thermally activated polarizations. LiBGeO4 ceramic sintered at 820 °C has optimum microwave dielectric properties with the relative permittivity (εr) of 6.28, a quality factor (Q × f) of 21,620 GHz, and a temperature coefficient of resonance frequency (τf) of -88.7 ppm/°C. LiBGeO4 also showed chemical inertness when cofired with silver (Ag), provided an evidence for its utilization in LTCC technology. Overall, this work provides a strategy for facile synthesis of phase pure borates, via the proposed two-step process to obtain stable boron resources. 相似文献
8.
Novel glass–free low temperature firing microwave dielectric ceramics Li2CeO3 with high Q prepared through a conventional solid‐state reaction method had been investigated. All the specimens in this paper have sintering temperature lower than 750°C. XRD studies revealed single cubic phase. The microwave dielectric properties were correlated with the sintering conditions. At 720°C/4 h, Li2CeO3 ceramics possessed the excellent microwave dielectric properties of εr = 15.8, Q × f = 143 700 (GHz), and τf = ?123 ppm/°C. Li2CeO3 ceramics could be excellent candidates for glass‐free low‐temperature co‐fired ceramics substrates. 相似文献
9.
《Journal of the European Ceramic Society》2014,34(15):4089-4093
Ultra-low firing microwave dielectric ceramic Pb2MoO5 with monoclinic structure was prepared via a conventional solid state reaction method. The sintering temperature ranged from 530 °C to 650 °C. The relative densities of the ceramic samples were about 97% when the sintering temperature was greater than 570 °C. The best microwave dielectric properties were obtained in the ceramic sintered at 610 °C for 2 h with a permittivity ∼19.1, a Q × f value about 21,960 GHz (at 7.461 GHz) and a temperature coefficient value of −60 ppm/°C. From the X-ray diffraction, backscattered electron image results of the co-fired samples with 30 wt% silver and aluminum additive, the Pb2MoO5 ceramics were found not to react with Ag and Al at 610 °C for 4 h. The microwave dielectric properties and ultra-low sintering temperature of Pb2MoO5 ceramic make it a promising candidate for low temperature co-fired ceramic applications. 相似文献
10.
Li He Di Zhou Feng Xiang Panpan Chang Yong Li Hong Wang 《Journal of the American Ceramic Society》2013,96(10):3027-3030
In this study, a novel spinel solid solution ceramic of 0.4LiFe5O8–0.6Li2MgTi3O8 (0.4LFO–0.6LMT) has been developed and investigated. It is found that the 40 mol% LiFe5O8 and 60 mol% Li2MgTi3O8 are fully soluble in each other and a disordered spinel phase is formed. The ceramic sample sintered at 1050°C/2 h exhibits both good magnetic and dielectric properties in the frequency range 1–10 MHz, with a permeability between 29.9~14.1 and magnetic loss tangent between 0.12~0.67, permittivity between 16.92~16.94 and dielectric loss tangent between 5.9 × 10?3–2.3 × 10?2. The sample also has good microwave dielectric properties with a relative permittivity of 16.1, a high quality factor (Q × f) ~28 500 GHz (at 7.8 GHz). Furthermore, 3 wt% H3BO3–CuO (BCu) addition can effectively lower the sintering temperature to 925°C and does not degrade the magnetodielectric properties. The chemical compatibility with silver electrode indicates that this kind of ceramics is a good candidate for the low‐temperature cofired ceramic (LTCC) application. 相似文献
11.
Structure,Microwave Dielectric Properties,and Novel Low‐Temperature Sintering of xSrTiO3–(1−x)LaAlO3 Ceramics with LTCC Application
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Shenhui Lei Huiqing Fan Weina Chen Zhiyong Liu Mengmeng Li 《Journal of the American Ceramic Society》2017,100(1):235-246
xSrTiO3–(1?x)LaAlO3 ceramics with ZnO–B2O3 sintering aid were prepared by solid‐state reaction method leading to a significant decrease in sintering temperature from 1550°C to 1050°C. The structure, microwave dielectric properties, and low‐temperature sintering behavior were systematically investigated. The results revealed the relationships among ionic size, ionic polarizability and cell volume. With increasing additive, chemical ordering of B‐site cations was indicated with selected area electron diffraction (SAED) patterns, HRTEM images and Raman spectrum, which contributed to the greatly enhanced microwave dielectric properties. Particularly, the 0.7Sr0.85 Mg0.15TiO3–0.3LaAlO3 ceramics modified with 10 wt % ZnO‐B2O3 can further decrease the sintering temperature down to 950°C without deteriorating its performance. Thermal tests implied ceramics featured good chemical compatibility with Cu/Ag electrode. Thus, they can be cofired with internal Cu/Ag electrodes in special patterns to fulfill different electrical functions for LTCC (low‐temperature cofired ceramic) application. 相似文献
12.
The CaMoO4–xY2O3–xLi2O ceramics were prepared by the solid‐state reaction method. The sintering behavior, phase evolution, microstructure, and microwave dielectric properties were investigated. CaMoO4 solid solution was obtained when x = 0.030, and two‐phase system including tetragonal CaMoO4 phase and cubic Y2O3 phase formed when 0.066 ≤ x ≤ 1.417. A temperature stable CaMoO4‐based microwave dielectric ceramic with ultralow sintering temperature (775°C) was obtained in the CaMoO4–xY2O3–xLi2O system when x = 0.306, which showed good microwave dielectric properties with a low permittivity of 9.5, a high Qf value of 63 240 GHz, and a near‐zero temperature coefficient of resonant frequency of +7.2 ppm/°C. 相似文献
13.
Di Zhou Wen‐Bo Li Li‐Xia Pang Jing Guo Ze‐Ming Qi Tao Shao Zhen‐Xing Yue Xi Yao 《Journal of the American Ceramic Society》2014,97(11):3597-3601
Ag2MoO4 ceramic was prepared by using the solid‐state reaction method, which could be sintered at 450°C for 2 h, having a relative permittivity of 8.08, a Qf value of 17 000 GHz, and a temperature coefficient of resonance frequency about ?133 ppm/°C. Ag2MoO4 ceramic was chemically compatible with silver but reacted seriously with aluminum to form (Ag0.5Al0.5)MoO4 during the sintering. The fitting of infrared spectra and the Shannon's additive rule were employed to study intrinsic dielectric behaviors of the ceramics at microwave region. Ionic displacive polarization and the electronic polarization contributed almost equally to the dielectric permittivity of the ceramic at microwave region. The Ag2MoO4 ceramics could be a good candidate for ultra‐low temperature co‐fired microwave devices. 相似文献
14.
Jing Guo Di Zhou Shen‐Li Zou Hong Wang Li‐Xia Pang Xi Yao 《Journal of the American Ceramic Society》2014,97(6):1819-1822
In this work, novel series of (1 ? x)Li2MO4–xTiO2 (M = Mo, W; x = 0.3, 0.4, 0.45, 0.5, 0.6) ceramics were developed for microwave dielectric application. They were prepared via the mixed‐oxide process and the phase composition, microstructures, sintering behaviors, and microwave dielectric properties were investigated. The X‐ray diffraction (XRD) pattern and scanning electron microscope analysis indicated that the Li2MO4 (M = Mo, W) did not react with rutile TiO2 and a stable two‐phase composite system Li2MO4–TiO2 (M = Mo, W) was formed. The XRD pattern of cofired ceramics revealed that some parts of Li2MoO4 phase and very small part of Li2WO4 phase react with Ag to form Ag2MoO4 phase and Ag2WO4 phase, respectively. At x = 0.45–0.5, temperature stable microwave dielectric materials with low sintering temperature (700°C–730°C) were obtained: εr = 10.6–11.0, Qf = 30 060–32 800 GHz, and temperature coefficient of resonant frequency ~0 ppm/°C. 相似文献
15.
Gao‐qun Zhang Jing Guo Li He Di Zhou Hong Wang Jurij Koruza Marija Kosec 《Journal of the American Ceramic Society》2014,97(1):241-245
A series of microwave dielectric ceramics in the compositions of K2Mo2O7, K2Mo3O10, and K2Mo4O13 in K2O–MoO3 binary system with ultra low sintering temperatures were prepared using the solid‐state reaction method. Their synthesis, phase composition, compatibility with metal electrodes, microstructures, and microwave dielectric properties were investigated. The K2Mo2O7 ceramic sintered at 460°C with a triclinic structure has a relative permittivity of 7.5, a Q × f value of 22 000 GHz, and a τf value of ?63 ppm/°C. The X‐ray diffraction patterns indicate that K2Mo2O7 does not react with Ag and Al electrodes at the co‐fired temperatures. The K2Mo3O10 ceramic can be sintered well at 520°C with a relative permittivity of 5.6, a Q × f value of 35 830 GHz, and a τf value of ?92 ppm/°C. It has compatibility with Ag electrode. The K2Mo4O13 ceramic sintered at 540°C possesses good microwave dielectric properties with a relative permittivity of 6.8, a Q × f value of 39 290 GHz and a τf value of ?67 ppm/°C and it is compatible with Al electrode. For K2Mo2O7 and K2Mo4O13, it is found that the grain sizes and the number of grain boundaries play an important role in the dielectric loss. From this study, it can be seen that the three ceramics in K2O–MoO3 system have good microwave dielectric properties, ultra‐low sintering temperatures, non‐toxic, and low‐cost characteristics. So they can be potentially applied to ultra‐LTCC devices. 相似文献
16.
Jing Guo Amanda L. Baker Hanzheng Guo Michael Lanagan Clive A. Randall 《Journal of the American Ceramic Society》2017,100(2):669-677
Cold sintering process (CSP) is an extremely low‐temperature sintering process (room temperature to ~200°C) that uses aqueous‐based solutions as transient solvents to aid densification by a nonequilibrium dissolution‐precipitation process. In this work, CSP is introduced to fabricate microwave and packaging dielectric substrates, including ceramics (bulk monolithic substrates and multilayers) and ceramic‐polymer composites. Some dielectric materials, namely Li2MoO4, Na2Mo2O7, K2Mo2O7, and (LiBi)0.5MoO4 ceramics, and also (1?x)Li2MoO4?xPTFE and (1?x)(LiBi)0.5MoO4?xPTFE composites, are selected to demonstrate the feasibility of CSP in microwave and packaging substrate applications. Selected dielectric ceramics and composites with high densities (88%‐95%) and good microwave dielectric properties (permittivity, 5.6‐37.1; Q × f, 1700‐30 500 GHz) were obtained by CSP at 120°C. CSP can be also used to potentially develop a new co‐fired ceramic technology, namely CSCC. Li2MoO4?Ag multilayer co‐fired ceramic structures were successfully fabricated without obvious delamination, warping, or interdiffusion. Numerous materials with different dielectric properties can be densified by CSP, indicating that CSP provides a simple, effective, and energy‐saving strategy for the ceramic packaging and microwave device development. 相似文献
17.
Plastic deformation and effects of water in room‐temperature cold sintering of NaCl microwave dielectric ceramics
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Wen Bin Hong Lei Li Meng Cao Xiang Ming Chen 《Journal of the American Ceramic Society》2018,101(9):4038-4043
NaCl ceramics were prepared by room‐temperature cold sintering using moistened NaCl powder with 4 wt% water and dry pressing using dehydrated powder. When the applied uniaxial pressure is low, the relative density of dry‐pressed NaCl ceramic is significantly lower than that of cold‐sintered ceramic, while the former is 98.5%‐99.3% and much higher than the latter (94.3%‐94.6%) for high applied pressure of 200‐300 MPa. The uniaxial pressure‐induced plastic deformation dominates the densification of dry‐pressed NaCl ceramic, and also plays a role during cold sintering as well as the dissolution‐precipitation process. The lower density of cold‐sintered NaCl ceramic under high applied pressure is attributed to the trapped water in ceramic body during cold sintering. Besides, the presence of water always promotes the microstructural homogeneity, which is responsible for the much higher Qf value of cold‐sintered NaCl ceramic. The optimal microwave dielectric properties with εr = 5.55, Qf = 49 600 GHz, and τf = ?173 ppm/°C are obtained in cold‐sintered NaCl ceramic under the applied pressure of 300 MPa, indicating that it is a promising candidate as a microwave dielectric material. 相似文献
18.
Ching‐Fang Tseng Po‐Ju Tseng Chi‐Min Chang Yu‐Chieh Kao 《Journal of the American Ceramic Society》2014,97(6):1918-1922
Novel microwave dielectric ceramics in the Li2MnO3 system with high Q prepared through a conventional solid‐state route had been investigated. All the specimens exhibited single phase ceramics sintered in the temperature range 1140°C–1230°C. The microwave dielectric properties of Li2MnO3 ceramics were strongly correlated with sintering temperature and density. The best microwave dielectric properties of εr = 13.6, Q × f = 97 000 (GHz), and τf = ?5.2 ppm/°C could be obtained as sintered at 1200°C for 4 h. BaCu(B2O5) (BCB) could effectively lower the sintering temperature from 1200°C to 930°C and slightly induced degradation of the microwave dielectric properties. The Li2MnO3 ceramics doped with 2 wt% BaCu(B2O5) had excellent dielectric properties of εr = 11.9, Q × f = 80 600 (GHz), and τf = 0 ppm/°C. With low sintering temperature and good dielectric properties, the BCB added Li2MnO3 ceramics are suitable candidates for LTCC applications in wireless communication system. 相似文献
19.
Yongqiang Li Mupeng Zheng Moyan Zang Mankang Zhu Yudong Hou 《Journal of the American Ceramic Society》2022,105(10):6262-6270
Because of large differences in the processing temperature windows between ceramics and polymers, the single-step co-sintering of microwave dielectric ceramic–polymer substrates remains challenging. In this work, a dense (Ca0.65Bi0.35)(Mo0.65V0.35)O4 (CBMVO) ceramic was first prepared through cold sintering at 150°C, under a uniaxial pressure of 300 MPa for 60 min with Li2MoO4 (LMO) as a transient low-temperature solvent. Cold-sintered CBMVO–5 wt% LMO ceramic shows excellent microwave dielectric properties: εr ∼ 11.4, Q × f ∼ 7070 GHz, τf ∼ −7.4 ppm/°C. Moreover, the optimized cold sintering process enabled the preparation of a layered co-sintered (2–2 type) CBMVO–polytetrafluoroethylene composite, which maintained excellent microwave dielectric properties and showed a good heterogeneous interface bonding. The proposed cold sintering co-firing of ceramic–polymer composites in a single step shows great potential for application in the seamless integration between ceramics and polymer substrates. 相似文献
20.
Microwave dielectric properties of SnO‐SnF2‐P2O5 glass and its composite with alumina for ULTCC applications
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Indira J. Induja Mailadil T. Sebastian 《Journal of the American Ceramic Society》2017,100(6):2632-2640
Ultralow‐temperature sinterable alumina‐45SnF2:25SnO:30P2O5 glass (Al2O3‐SSP glass) composite has been developed for microelectronic applications. The 45SnF2:25SnO:30P2O5 glass prepared by melt quenching from 450°C has a low Tg of about 93°C. The SSP glass has εr and tanδ of 20 and 0.007, respectively, at 1 MHz. In the microwave frequency range, it has εr=16 and Qu × f=990 GHz with τf=?290 ppm/°C at 6.2 GHz with coefficient of thermal expansion (CTE) value of 17.8 ppm/°C. A 30 wt.% Al2O3 ‐ 70 wt.% SSP composite was prepared by sintering at different temperatures from 150°C to 400°C. The crystalline phases and dielectric properties vary with sintering temperature. The alumina‐SSP composite sintered at 200°C has εr=5.41 with a tanδ of 0.01 (1 MHz) and at microwave frequencies it has εr=5.20 at 11 GHz with Qu × f=5500 GHz with temperature coefficient of resonant frequency (τf)=?18 ppm/°C. The CTE and room‐temperature thermal conductivity of the composite sintered at 200°C are 8.7 ppm/°C and 0.47 W/m/K, respectively. The new composite has a low sintering temperature and is a possible candidate for ultralow‐temperature cofired ceramics applications. 相似文献