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Dielectric and piezoelectric properties of(Li,Ce) modified NaBi_5Ti_5O_(18) composite ceramics 被引量:7
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作者 马磊 赵琨 +3 位作者 李吉夏 吴琪 赵明磊 王春雷 《Journal of Rare Earths》 SCIE EI CAS CSCD 2009年第3期496-500,共5页
Nominal (Li0.5Ce0.5)x(Na0.5Bi0.5)(1-x)Na0.5Bi4.5Ti5O18 composite ceramics were fabricated using conventional solid-state reaction method. The coexistence of bismuth layer-structured phase and perovskite phase wa... Nominal (Li0.5Ce0.5)x(Na0.5Bi0.5)(1-x)Na0.5Bi4.5Ti5O18 composite ceramics were fabricated using conventional solid-state reaction method. The coexistence of bismuth layer-structured phase and perovskite phase was determined in these ceramics using XRD technique. At room temperature, the x=0.11 sample showed the largest piezoelectric constant, d33, of about 26.5 pC/N and the largest electromechanical coupling factor, kt, of about 30%. Even after annealing at 500 ℃, the value of d33 was still about 19 pC/N, in x=0.08-0.11 samples. Moreover these composite ceramics showed low temperature coefficients of dielectric constant and high electrical resistivity in the temperature region of 450-550 ℃. These results indicated that (Li, Ce) modified NaBi5Ti5O18 composite ceramics were promising piezoelectric materials for high-temperature applications. 展开更多
关键词 FERROELECTRICS composite ceramics dielectric properties piezoelectric properties electrical resistivity rare earths
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Low-temperature sintering and microwave dielectric properties of Li_2MgTi_3O_8 ceramics doped with BaCu(B_2O_5) 被引量:3
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作者 包燕 陈国华 +6 位作者 侯美珍 韩作鹏 邓开能 杨云 袁昌来 周昌荣 刘心宇 《Journal of Central South University》 SCIE EI CAS 2012年第5期1202-1205,共4页
The influences of BaCu(B2O5) (BCB) addition on sintering, microstructure and microwave dielectric properties of Li2MgTi308 ceramics were investigated using X-ray diffractometry, scanning electron microscopy and mi... The influences of BaCu(B2O5) (BCB) addition on sintering, microstructure and microwave dielectric properties of Li2MgTi308 ceramics were investigated using X-ray diffractometry, scanning electron microscopy and microwave dielectric measurements. The experimental results show that a small amount of BaCu(B2O5) addition can effectively reduce the sintering temperature to 900℃, and induce only a limited degradation of the microwave dielectric properties. Typically, the best microwave dielectric properties of er24.5, Q×f =24 622 GHz, rf=4.2×10-6℃ -1 are obtained for 1.0% BCB-doped Li2MgTi3O8 ceramics sintered at 900℃ for 3 h. The BCB-doped Li2MgTi3O8 ceramics can be compatible with Ag electrode, which may be a strong candidate for low temperature co-fired ceramics applications. 展开更多
关键词 ceramics dielectrics low-temperature co-fired ceramics microwave dielectric properties
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Microstructure and microwave dielectric properties of ZnO-B_2O_3 added (Ca_(0.254)Li_(0.19)Sm_(0.14))TiO_3 ceramics 被引量:2
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作者 LU Yin LI Haitao +1 位作者 LI Qian ZHANG Boping 《Rare Metals》 SCIE EI CAS CSCD 2010年第3期243-247,共5页
The effects of ZnO-B2O3 (ZB2) on the sintering behavior and microwave dielectric properties of (Ca0.254Li0.19Sm0.14)TiO3 ceramics were investigated. The densities of the specimens reached the maximum value by addi... The effects of ZnO-B2O3 (ZB2) on the sintering behavior and microwave dielectric properties of (Ca0.254Li0.19Sm0.14)TiO3 ceramics were investigated. The densities of the specimens reached the maximum value by adding 3 wt.% ZB2 and then decreased. The sintering temperature of the specimens was lowered from 1300 to 1100℃ without degradation of the microwave dielectric properties. The (Ca0.254Li0.19Sm0.14)TiO3+ 3 wt.% ZB2 sintered at 1100℃ for 3 h showed good microwave dielectric properties, εr= 108.2, Qf= 6545 GHz, and rf= 6.5 ppm/℃, respectively, indicating that ZB2 was an effective sintering aid to improve the densification and microwave dielectric properties of (Ca0.254Li0.19Sm0.14)TiO3 ceramics. 展开更多
关键词 microwave dielectric properties DENSIFICATION ceramics sintering behavior
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Formation and Dielectric Properties of Mn-Doped BSTN Composite Ceramics
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作者 周宗辉 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第1期1-3,共3页
The influence of Mn doping on the formation and dielectric properties of 0.7BaO·0.3SrO·(1-y)TiO2·yNb2O5 (BSTN) composite ceramics were investigated. The Mn was doped according to the formula 0.7BaO&... The influence of Mn doping on the formation and dielectric properties of 0.7BaO·0.3SrO·(1-y)TiO2·yNb2O5 (BSTN) composite ceramics were investigated. The Mn was doped according to the formula 0.7BaO·0.3SrO·(0.7-z)TiO2·0.3Nb2O5·zMnO2 (BSTNM). The results show the two phases, perovskite phase BST and the tungsten bronze phase SBN, are coexistence in BSTNM as they are in BSTN composite ceramics. The Mn ions doped in BSTN substitute for Nb5+ ions in the tungsten bronze phase, and then, the Nb5+ ions substitute for Ti4+ ions in the perovskite phase. With the increasing of Mn dopant, the content of the perovskite phase increases while that of the tungsten bronze phase decreases, and the grain size of the perovskite phase decreases. As well as, the phase transition temperature of tungsten bronze phase increases with value z increasing from 0 to about 0.05. 展开更多
关键词 MN BSTN composite ceramics FORMATION dielectric properties
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Effect of La_2O_3-Dopant on Microstructure and Microwave Dielectric Properties of CaO-MgO-Nb_2O_5-TiO_2 System Ceramics
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作者 王浩 陈文 刘涛 《Journal of Rare Earths》 SCIE EI CAS CSCD 2005年第1期32-35,共4页
La_2O_3-doped CaO-MgO-Nb_2O_5-TiO_2 system ceramics were prepared by solid-state ceramic technique. The microstructure and microwave dielectric properties of CaO-MgO-Nb_2O_5-TiO_2-La_2O_3 ceramics can be adjusted by v... La_2O_3-doped CaO-MgO-Nb_2O_5-TiO_2 system ceramics were prepared by solid-state ceramic technique. The microstructure and microwave dielectric properties of CaO-MgO-Nb_2O_5-TiO_2-La_2O_3 ceramics can be adjusted by varying the amount of La^(3+) ions. The results show that the replacement of Ca^(2+) by La^(3+) at A-site of the ceramics can increase the quality factor Q·f value as well as the temperature coefficient of resonant frequency τ_f and decrease the dielectric constant ε_r. With increase of La^(3+) contents, the dielectric constant decreases from 57 to 35 and Q·f value increases from 33400 GHz to 35000 GHz (at 7.6 GHz). Meanwhile, the temperature coefficient of resonant frequency is improved towards near zero. The dielectric properties of these compounds are related to octahedra tilting due to deficient vacancies at A-site. 展开更多
关键词 inorganic nonmetallic materials PEROVSKITE microwave dielectric ceramics dielectric properties rare earths
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Effect of La^(3+), Sr^(2+) on Microwave Dielectric Properties of CaO-MgO-Nb_2O_5^-TiO_2 System Ceramics
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作者 Wang Hao Chen Wen Tian Zhongqing 《Journal of Rare Earths》 SCIE EI CAS CSCD 2006年第1期80-80,共1页
The effect of La^3 + , Sr^2+ on the microstructure and microwave properties of CaO-MgO-Nb2O5-TiO2 system ceramics was investigated. The result shows that a single complex perovskite structure formed within investiga... The effect of La^3 + , Sr^2+ on the microstructure and microwave properties of CaO-MgO-Nb2O5-TiO2 system ceramics was investigated. The result shows that a single complex perovskite structure formed within investigated composition range in La^3+ , Sr2-doped CaO-MgO-Nb2O5-TiO2 system ceramics. With increasing of La^3+ , Sr^2+ content, the structure of La^3+ , Sr2-doped CaO-MgO-Nb2O5-TiO2 system ceramic respectively maintain orthorhombic type. 展开更多
关键词 inorganic nonmetallic materials PEROVSKITE microwave dielectric ceramics dielectric properties rare earths
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Effect of Rare Earth Oxides on the Microstructure and Microwave Dielectric Properties of CaO-MgO-Nb_2O_5-TiO_2 System Ceramics
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作者 王浩 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2005年第4期83-86,共4页
La2O3 and SrO-doped CaO-MgO-Nb2O3-TiO2 system ceramics were prepared by solid-state ceramic technique.The microstructure and microwave dielectric properties of CaO-MgO-Nb2O5-TiO2-La2O3 cermics can be adjusted by varyi... La2O3 and SrO-doped CaO-MgO-Nb2O3-TiO2 system ceramics were prepared by solid-state ceramic technique.The microstructure and microwave dielectric properties of CaO-MgO-Nb2O5-TiO2-La2O3 cermics can be adjusted by varying the amount of La^3+ or Sr^2+ ions respectively.The replacement of Ca^2+ by La^3+ at A-site of the ceramics increases the quality factor Q value( at 7.6GHz)as well as the temperature coefficient of resonant frequency τf and decreases the dielectric constant εr and the substitution of Sr^2+ at A-site in this ceramics system exhibits opposite characteristics.The microwave properties of La^3+,Sr^2+-doped CaO-MgO-Nb2O5-TiO2 system ceramics depend on the degree of octahedral distortion inside materials. 展开更多
关键词 PEROVSKITE microwave dielectric ceramic dielectric properties
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Effects of V<sub>2</sub>O<sub>5</sub>Addition on Microwave Dielectric Properties of Li<sub>2</sub>ZnTi<sub>3</sub>O<sub>8</sub>Ceramics for LTCC Applications
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作者 Jianhua Zhu Jinyuan Liu +1 位作者 Songjie Lu Yong Zeng 《New Journal of Glass and Ceramics》 2019年第3期25-32,共8页
The sintering temperature of Li2ZnTi3O8 ceramics is still high for LTCC-based applications. In this work, V2O5 was doped as the sintering aid. The sintered density, phase composition, grain size, as well as microwave ... The sintering temperature of Li2ZnTi3O8 ceramics is still high for LTCC-based applications. In this work, V2O5 was doped as the sintering aid. The sintered density, phase composition, grain size, as well as microwave dielectric properties of Li2ZnTi3O8 ceramics with the addition of V2O5 were investigated. Based on our research, V2O5 doping effectively promoted the densification of Li2ZnTi3O8 ceramics at about 900°C, without affecting the main crystal phase of the ceramics. Li2ZnTi3O8 ceramics with 0.5 wt% V2O5 doping (sintered at 900°C) exhibited the best microwave dielectric properties (Qf =?22,400 GHz at about 6 GHz, εr = 25.5, and τf = -10.8 ppm/°C). The V2O5-doped Li2ZnTi3O8 ceramics were well cofired with Ag inner paste without cracks and diffusion, indicating its significant potential for LTCC applications. 展开更多
关键词 Li2ZnTi3O8 Low Temperature Co-Fired ceramics microwave dielectric properties
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Influence of Heat-treatment on Microwave Dielectric Properties of SiO_2-Al_2O_3-SrO-ZnO-La_2O_3 Glass-ceramic System
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作者 CHEN Geng Qi Ping WANG Wei 《科技信息》 2011年第16期I0162-I0163,共2页
The influence that the holding time exerts on the microwave dielectric property of the glass-ceramic of SiO2-Al2O3-SrO-ZnO-La2O3under 750℃ is studied.The dielectric property is measured by perturbation method and the... The influence that the holding time exerts on the microwave dielectric property of the glass-ceramic of SiO2-Al2O3-SrO-ZnO-La2O3under 750℃ is studied.The dielectric property is measured by perturbation method and the microcrystalline phase has been analyzed by XRD and SEM.The new glass phase La2ZrTiO7 produced by the reaction(Q=1800,τε=+500ppm/℃) is of great signality to the development of new microwave dielectric materials.The sample which was insulated at 750℃ for 35h with superior dielectric properties: εr=12.82,Q=1150,τε=-19.5ppm/℃. 展开更多
关键词 绝缘道具 微波 热疗 玻璃 陶器
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Dielectric tunable properties of BaTi_4O_9-doped Ba_(0.6)Sr_(0.4)TiO_3 microwave composite ceramics 被引量:3
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作者 ZHANG JingJi, ZHAI JiWei, JIANG HaiTao & YAO Xi Functional Materials Research Laboratory, Tongji University, Shanghai 200092, China 《Science China(Technological Sciences)》 SCIE EI CAS 2009年第1期116-122,共7页
BaTi4O9-doped Ba0.6Sr0.4TiO3 (BST) composite ceramics were prepared by the conventional solid-state reaction and their structure, dielectric nonlinear characteristics and microwave dielectric properties were investiga... BaTi4O9-doped Ba0.6Sr0.4TiO3 (BST) composite ceramics were prepared by the conventional solid-state reaction and their structure, dielectric nonlinear characteristics and microwave dielectric properties were investigated. The secondary phase of the orthorhombic structure Ba4Ti13O30 is formed among BST composite ceramics with the increase of BaTi4O9. At the same time, a duplex or bimodal grains size distribution shows fine grains in a coarse grain matrix. The degree of frequency dispersion of dielectric permittivity below Tm is increased initially and then decreased with respect to BaTi4O9. As the BaTi4O9 content increases, the tunability of composite ceramics decreases, while the Q value increases. Inter-estingly, 70 wt% BaTi4O9-doped BST has a tunability ~4.0% (under 30 kV/cm biasing) versus a permit- tivity ~68 and quality factor ~134.1 (at ~3.2 GHz). 展开更多
关键词 tunability microwave dielectric properties composite ceramics
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Microwave dielectric properties and compatibility with silver of low-fired Li_2MgTi_3O_8 ceramics with Li_2O-MgO-B_2O_3 frit
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作者 包燕 陈国华 +3 位作者 侯美珍 杨云 韩作鹏 邓开能 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第11期3318-3323,共6页
The effects of Li2O-MgO-B2O3 (LMB) glass additive on the sintering characteristics, phase purity, microstructure, and microwave dielectric properties of Li2MgTi3O8 ceramics were investigated. The experimental result... The effects of Li2O-MgO-B2O3 (LMB) glass additive on the sintering characteristics, phase purity, microstructure, and microwave dielectric properties of Li2MgTi3O8 ceramics were investigated. The experimental results demonstrate that the addition of LMB glass effectively lowers the sintering temperature of Li2MgTi3O8 ceramic from 1025 ℃ to 875 ℃ and induces no obvious degradation of the microwave dielectric properties. Typically, the 1.5%LMB glass-added Li2MgTi3O8 ceramic sintered at 875 ℃ for 4 h shows excellent microwave dielectric properties of Q×f=45403 GHz, εr=25.9 and τf≈0 ℃-1. The dielectric ceramic exhibits stability against the reaction with the Ag electrode, which indicates that the ceramics could be applied in multilayer microwave devices requiring low firing temperatures. 展开更多
关键词 microwave ceramics dielectric properties GLASS low-temperature sintering compatibility
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Effect of Sb-site nonstoichiometry on the structure and microwave dielectric properties of Li_(3)Mg_(2)Sb_(1-x)O_(6) ceramics 被引量:7
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作者 Cuijin PEI Jingjing TAN +5 位作者 Yang LI Guoguang YAO Yanmin JIA Zhaoyu REN Peng LIU Huaiwu ZHANG 《Journal of Advanced Ceramics》 SCIE CAS CSCD 2020年第5期588-594,共7页
The non-stoichiometric Li_(3)Mg_(2)Sb_(1-x)O_(6)(0.05≤x≤0.125)compounds have been prepared via the mixed oxide method.The influences of Sb nonstoichiometry on the sintering behavior,microstructure,phase composition ... The non-stoichiometric Li_(3)Mg_(2)Sb_(1-x)O_(6)(0.05≤x≤0.125)compounds have been prepared via the mixed oxide method.The influences of Sb nonstoichiometry on the sintering behavior,microstructure,phase composition along with microwave dielectric performances for Li_(3)Mg_(2)Sb_(1-x)O_(6) ceramics were studied.Combined with X-ray diffraction(XRD)and Raman spectra,it was confirmed that phase composition could not be affected by the Sb nonstoichiometry and almost pure phase Li_(3)Mg_(2)SbO_(6) was formed in all compositions.Appropriate Sb-deficiency in Li_(3)Mg_(2)SbO_(6) not only lowered its sintering temperature but also remarkably improved its Q×f value.In particular,non-stoichiometric Li_(3)Mg_(2)Sb_(0.9)O_(6) ceramics sintered at 1250℃/5 h owned seldom low dielectric constant ε_(r)=10.8,near-zero resonant frequency temperature coefficient τ_(f)=-8.0 ppm/℃,and high quality factor Q×f=86,300 GHz(at 10.4 GHz).This study provides an alternative approach to ameliorate its dielectric performances for Li_(3)Mg_(2)SbO_(6)-based compounds through defect-engineering. 展开更多
关键词 microwave dielectric properties ceramics SINTERING antimony compounds
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Effect of TiO_2 content on the microwave dielectric properties of BaO-ZnO-TiO_2 ceramics 被引量:1
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作者 YU ShengQuan LONG MingZhu +2 位作者 TANG Bin ZHANG ShuRen ZHOU XiaoHua 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第6期1532-1536,共5页
In this paper,the BaO-0.6ZnO-xTiO2 ceramics with x=2.5-2.8 have been prepared by the conventional solid-state ceramic route for the purpose of investigating the effect of TiO2 content on the microwave dielectric prope... In this paper,the BaO-0.6ZnO-xTiO2 ceramics with x=2.5-2.8 have been prepared by the conventional solid-state ceramic route for the purpose of investigating the effect of TiO2 content on the microwave dielectric properties.The XRD results showed that the main crystal phase in the sintered ceramics was Ba4ZnTi11O27 and that the additional phases:Ba2ZnTi5O13 and BaZn2.03Ti3.93O10.89 were presented,depending on the TiO2 contents.The SEM photographs of the samples sintered at 1200℃ for 2 h showed a high compact microstructure.Because the phase composition of ceramics samples was changed with TiO2 content,the dielectric constant(εr),the quality factor values(Q×f) and the temperature coefficient of resonant frequency(τf) were first increased,continuously came up to a peak value,and then let up.It was lucky to find that the sample with composition BaO-0.6ZnO-2.7TiO2 had both the maximum dielectric constant εr=36.1 and the maximum Q×f value of 29320 GHz,and more importantly,it had an acceptable temperature coefficient of resonant frequency τf=10.45 ppm/℃. 展开更多
关键词 dielectric properties microwave ceramics SINTERING BaO-ZnO-TiO2
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Crystal structures and microwave dielectric properties of Sr_(2)MgWO_(6) ceramics at different sintering temperatures 被引量:1
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作者 Jiqing Lv Zhikai Cao +2 位作者 Yuying Wang Feng Shi Jing Wang 《Journal of Materiomics》 SCIE 2022年第1期79-87,共9页
Sr_(2)MgWO_(6)(SMW)is a typical perovskite oxide compound,but there has been little research on the effects of processing on its dielectric properties.In this work,SMW ceramics were prepared by solid-state synthesis w... Sr_(2)MgWO_(6)(SMW)is a typical perovskite oxide compound,but there has been little research on the effects of processing on its dielectric properties.In this work,SMW ceramics were prepared by solid-state synthesis with sintering at 1450℃,1475℃,1500℃and 1525℃,respectively.XRD results confirmed that the samples possessed double perovskite structure(Fm-3m).The Raman and FTIR spectra were used to study the lattice vibrational modes.The FPSQ model was used to obtain the fitting curves of the FTIR spectra and derive the intrinsic properties of the material that were found to be in agreement with the measured data.The structure-property relationships were successfully established based on the Raman mode results.The optimal sintering temperature of SMW ceramics was identified as 1475℃due to the excellent performances characteristics(ε_(r)=16.97,Q×f=23,872 GHz,τ_(f)=-35.38 ppm/℃)obtained at this temperature.This study explored the relationships among the crystal structures,lattice vibrational characteristics and dielectric properties of SMW ceramics,so as to further understand their dielectric response mechanism and lay a solid theoretical foundation for the development of microwave ceramics. 展开更多
关键词 microwave dielectric ceramics Crystal structures Intrinsic properties Lattice vibrational characteristics Structure-property relationships
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Sintering characteristics and microwave dielectric properties of 0.5Ca_(0.6)La_(0.267)TiO_3-0.5Ca(Mg_(1/3)Nb_(2/3))O_3 ceramics prepared by reaction-sintering process 被引量:1
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作者 Jiamao Li Peng Xu +1 位作者 Tai Qiu Lichun Yao 《Journal of Rare Earths》 SCIE EI CAS CSCD 2018年第4期404-408,共5页
0.5 Ca(0.6La0.267TiO3-0.5 Ca(Mg1/3Nb2/3)O3(5 CLT-5 CMN) ceramics were prepared by a reaction-sintering process and their sintering characteristics, microwave dielectric properties were investigated in detail.With... 0.5 Ca(0.6La0.267TiO3-0.5 Ca(Mg1/3Nb2/3)O3(5 CLT-5 CMN) ceramics were prepared by a reaction-sintering process and their sintering characteristics, microwave dielectric properties were investigated in detail.Without any calcination stage involved,a mixture of CaCO_3, La_2 O_3, TiO_2, MgO and Nb_2 O_5 was pressed and sintered directly. Pure phase 5 CLT-5 CMN ceramics with high density and dense microstructure can be obtained after sintered at 1400 ℃ for 4 h. Compared with those prepared by the conventional ceramic route, 5 CLT-5 CMN ceramics produced by the reaction-sintering process exhibit slightly higher dielectric constant and Q×f value. Fine microwave dielectric properties of ε_r= 56.4, Q×f= 48,550 GHz and T_f = +8.7 ppm/℃ for 5 CLT-5 CMN ceramics sintered at 1400 ℃ for 4 h are obtained, suggesting reactionsintering process is a simple and efficient method to produce pure phase 5 CLT-5 CMN ceramics as a potential candidate for the fabrication of microwave devices. 展开更多
关键词 microwave ceramics Sintering behavior dielectric properties Reaction sintering Rare earths
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Natural Rubber Based Composites Comprising Different Types of Carbon-Silica Hybrid Fillers. Comparative Study on Their Electric, Dielectric and Microwave Properties, and Possible Applications 被引量:1
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作者 Ahmed A. Al-Ghamdi Omar A. Al-Hartomy +4 位作者 Falleh R. Al-Solamy Nikolay Dishovsky Mihail Mihaylov Petrunka Malinova Nikolay Atanasov 《Materials Sciences and Applications》 2016年第6期295-306,共12页
The paper presents a comparative study on the electric, dielectric and microwave properties of natural rubber based composites comprising dual phase fillers prepared from furnace carbon black or conductive carbon blac... The paper presents a comparative study on the electric, dielectric and microwave properties of natural rubber based composites comprising dual phase fillers prepared from furnace carbon black or conductive carbon black with a different amount of silica. It has been established that, the specifics of the carbon phase have a marked strong effect upon the properties mentioned above. The interpenetration of the two filler phases and the grade of isolation of the conductive carbon phase by the dielectric one depend on the ratio between them. On the other hand, that leads to a change in all properties of the studied composites, which allows tailoring those characteristics. 展开更多
关键词 Polymer composites Hybrid Fillers dielectric properties microwave properties
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Structure and Dielectric Properties of ZnO and Nb_2O_5 Doped BaO-TiO_2 System Microwave Ceramics
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作者 陈力颖 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2008年第5期647-651,共5页
The microwave dielectric properties and microstructure of BaTi4.3ZnyO9.6+y +0.02 mol% SnO2+0.01 mol% MnCO3+x mol% Nb2O5(x=0-0.05, y=0-0.08) system ceramics were studied as a function of the amount of ZnO and Nb2... The microwave dielectric properties and microstructure of BaTi4.3ZnyO9.6+y +0.02 mol% SnO2+0.01 mol% MnCO3+x mol% Nb2O5(x=0-0.05, y=0-0.08) system ceramics were studied as a function of the amount of ZnO and Nb2O5 doped. Addition of (y=0-0.05) ZnO and (x=0-0.025) Nb2O5 enhanced the reactivity and decreased the sintering temperature effectively. It also increased the dielectric constant ε r and quality factor Q(=1/tan 8) of the system due to the substitution of Ti^4+ ions with incorporating Zn^2+and Nb^5+ ions, which was analyzed by the reaction ZnO+Nb2O5+ 3 TiTxTi →ZnTi+ 2NbTi+3TiO2. When the system doped with (y=0.05) ZnO and (x=0.025) Nb205 were sintered at 1 160 ℃ for 6 h, the εr. Qf0 value and rfwere 36.5, 42 000 GHz, and+1.8 ppm/℃, respectively, at 5 GHz. 展开更多
关键词 ceramics microwave dielectric properties ZnO dopant Nb2O5 dopant
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Low-Temperature Sintering and Microwave DielectricProperties of Ba_2Ti_3Nb_4O_(18) Ceramics
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作者 胡云香 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2011年第5期847-851,共5页
The effects of CuO and H3BO3 additions on the low-temperature sintering,microstructure,and microwave dielectric properties of Ba2Ti3Nb4O18 ceramics were investigated.The addition of less amount of CuO ( 〈1 wt%) con... The effects of CuO and H3BO3 additions on the low-temperature sintering,microstructure,and microwave dielectric properties of Ba2Ti3Nb4O18 ceramics were investigated.The addition of less amount of CuO ( 〈1 wt%) considerably facilitated the densification of Ba2Ti3Nb4O18 ceramics.Appropriate addition of H3BO3 ( 〈3.5 wt%) remarkably improved the microwave dielectric properties of ceramics.The addition of H3BO3 and CuO successfully reduced the sintering temperature of Ba2Ti3Nb4O18 ceramics from 1300 to 1050 ℃.Ba2Ti3Nb4O18 ceramics sintered at 1 050 ℃ for 4 h with the addition of 1.0 wt% CuO and 3.5 wt% H3BO3 exhibited good microwave dielectric properties:er=33.74,Q?f=13 812 GHz,and tf=-5.35 ppm/°C at about 5.0 GHz. 展开更多
关键词 Ba2Ti3Nb4O18 ceramics microwave dielectric properties low-temperature sintering CuO and H3BO3 additions
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Structure and Dielectric Properties of Sb_2O_5-Doped ZrO_2-SnO_2-TiO_2 Microwave Ceramics
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作者 陈力颖 吴顺华 《Transactions of Tianjin University》 EI CAS 2006年第6期438-441,共4页
The microwave dielectric properties of ZrO2-SnO2-TiO2 (ZST) system ceramics were studied as a function of the amount of Sb2O5 dopant. With the addition of 0-0.5% Sb2O5(molar ratio), the substitution of Ti4^+ ions... The microwave dielectric properties of ZrO2-SnO2-TiO2 (ZST) system ceramics were studied as a function of the amount of Sb2O5 dopant. With the addition of 0-0.5% Sb2O5(molar ratio), the substitution of Ti4^+ ions with Sb^5+ ions decreased the sintering temperature and increased the quality factor Q due to the reduction of oxygen vacancies, When the amount of Sb^5+ increased further (above 0.5%), Q was decreased by increasing the electron concentration. When the system doped with 0.5% Sb2O5 was sintered at 1 150℃ for 6 h, the relative dielectric constant ε, Qf0, and the temperature coefficient of resonant frequency (TCF) were 38.46, 44 500 GHz, 20.0×10^-6/℃, respectively, at 6 GHz, 展开更多
关键词 ceramics microwave dielectric properties Sb2O5 dopant
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Effects of thermal oxidation on microwave-absorbing and mechanical properties of SiC_f/SiC composites with PyC interphase 被引量:2
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作者 史毅敏 罗发 +3 位作者 丁冬海 穆阳 周万城 朱冬梅 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第5期1484-1489,共6页
The SiCf/SiC composites containing PyC interphase were prepared by chemical vapor infiltration process. The influences of thermal oxidation on the complex permittivity and microwave absorption properties of Si Cf/Si C... The SiCf/SiC composites containing PyC interphase were prepared by chemical vapor infiltration process. The influences of thermal oxidation on the complex permittivity and microwave absorption properties of Si Cf/Si C composites were investigated in the frequency range of 8.2-12.4 GHz. Both the real and imaginary parts of the complex permittivity decreased after thermal oxidation. The composites after 100 h thermal oxidation showed that reflection loss exceeded-10 d B in the frequency of 9.7-11.9 GHz and the minimum value was-11.4 d B at 11.0 GHz. The flexural strength of composites decreased but fracture behavior was improved obviously after thermal oxidation. These results indicate that the SiCf/SiC composites containing PyC interphase after thermal oxidation possess good microwave absorbing property and fracture behavior. 展开更多
关键词 SiCf/SiC composites thermal oxidation dielectric properties microwave absorbing mechanical properties
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