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Ti-B位置换改性Mg2SiO4陶瓷微结构和微波介电性能的研究中发现,在合成Mg2SiO4陶瓷过程中,Mg2SiO3总是作为第二相出现,Ti的引入能够有效地抑制Mg2SiO3的出现.但Ti不是进入Si-O四面体取代置换Si形成Mg2(Si1-xTixO4固溶体,而是Mg与反应形成Mg2TiO4、Mg2Ti2O5等第二相.Mg2(Si1-xTix)O4陶瓷随着值x增加,介电常数εr从6.8增加到8.1,Qf值也获得显著改善,但谐振频率温度系数不会因Ti引入而得到优化.在x=0.1时,Mg2(Si0.9Ti0.1)O4陶瓷获得优良的微波介电性能:εr=7.4,Qf=73 760GHz,τf=60·10-6/℃. 相似文献
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《硅酸盐学报》2015,(9)
通过Co2+对Mg2+的取代,探讨不同x值下Ca(Mg1–xCox)Si2O6陶瓷的物相组成、烧结性能、微观结构以及微波介电性能。结果表明:Co2+对Mg2+的取代,可将Ca(Mg1–xCox)Si2O6陶瓷的烧结温度从1300℃降低至1 175℃;Co2+在Ca(Mg,Co)Si2O6中的固溶极限在0.2~0.3之间,Mg2+在Ca(Co,Mg)Si2O6中的固溶极限在0.3~0.4之间,当x位于0.3~0.6之间时,出现Ca(Mg,Co)Si2O6与Ca(Co,Mg)Si2O6两相共存;无论是Co2+固溶入Ca Mg Si2O6,形成Ca(Mg,Co)Si2O6,还是Mg2+固溶进入Ca Co Si2O6,形成Ca(Co,Mg)Si2O6,陶瓷晶粒均随固溶度的增大,出现异常长大,进而恶化陶瓷的品质因数。当x=0.5时,Ca(Mg,Co)Si2O6与Ca(Co,Mg)Si2O6两相共存,有效细化了陶瓷晶粒尺寸,1 225℃烧结后,陶瓷的微波介电性能为εr=8.04,品质因数Q×f=59 108 GHz,谐振频率温度系数τf=–51.02×10–6/℃。 相似文献
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研究了V2O5对Mg4Nb2O9陶瓷的烧结温度、相结构和微波介电性能的影响.结果表明,添加1%~8%的V2O5,能使该陶瓷的烧结温度降低到1000~1050℃而对其微波介电性能的影响很小,材料的主晶相为有序型刚玉结构的Mg4 Nb2O9,存在Mg4Nb2O6和Mg5Nb4O15杂相而没有检测到V2O5的存在.陶瓷的密度对微波介电性能起着决定性作用,介电常数e1与密度成线性关系(在99.99%的置信限内,其相关系数为0.98252),Q·f值与密度的关系较复杂.添加1%的v2O5,将Mg4Nb2O9陶瓷的烧结温度降低到了1050℃,得到了εr=12.72,Q·f=151040GHz的优异性能. 相似文献
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(Ca1+ x Sm1− x )(Al1− x Ti x )O4 (0≤ x ≤0.4) ceramics were synthesized by solid-state reaction method and their microstructures and microwave dielectric properties were investigated. X-ray diffraction analysis and energy-dispersive X-ray analysis indicated that the matrix phase was a solid solution with a composition represented by the chemical formula (Ca1+ x Sm1− x ) (Al1− x Ti x )O4 and minor amount of (Ca,Sm)(Al,Ti)O3 secondary phase was detected. Ca/Ti cosubstitution could significantly improve the microwave dielectric characteristics of CaSmAlO4 ceramics, and the excellent microwave dielectric characteristics were obtained in the modified ceramics as ɛr =19–23, Q × f =49 100–118 700 GHz, and τf =−15–15 ppm/°C. 相似文献
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Effect of Zn/Si Ratio on the Microstructural and Microwave Dielectric Properties of Zn2 SiO4 Ceramics
Ngoc-Huan Nguyen Jong-Bong Lim Sahn Nahm Jong-Hoo Paik Jong-Hee Kim 《Journal of the American Ceramic Society》2007,90(10):3127-3130
Zn2 SiO4 ceramics synthesized by the conventional solid-state method exhibited a low Q × f value, possibly due to the formation of a ZnO second phase. However, with a small ZnO reduction from the Zn2 SiO4 ceramics, the ZnO second phase disappeared and grain growth occurred due to the formation of a Si-rich liquid phase. Specimens with a large grain size exhibited an improved Q × f value. In particular, the ceramics with nominal composition Zn1.8 SiO3.8 sintered at 1300°C exhibited improved microwave dielectric properties of ɛr =6.6, Q × f =147 000 GHz, and τf =−22 ppm/°C. 相似文献
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Mg4Nb2O9具有与α-Al2O3相同的刚玉型晶体结构,可望成为新一代高Q、低ε基板材料.然而,该材料却具有很大的负谐振频率温度系数(τf=-7.05×10-5/℃),期望通过添加TiO2(τf=4.50×10-4/℃)以达到调整的目的.适量的添加TiO2将Mg4Nb2O9陶瓷的烧结温度降低了约100℃,并增强了陶瓷的性能,微波介电性能与其密度呈线性关系.由于添加的TiO2与Mg5Nb4O15反应形成了(Ng,Ti)5(Nb,Ti)4O15第二相,使得TiO2对该陶瓷τf值的调整作用不显著.1300℃、5h烧结添加质量分数为2.5%的TiO2的Mg4Nb2O9陶瓷具有最佳的性能:εr=13.61,Q·f=196620GHz,τf=-5.04×10-5/℃. 相似文献
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《硅酸盐学报》2015,(9)
采用传统陶瓷固相反应烧结法制备(Mg1–xYx)2Al4Si5O18陶瓷。Y3+掺杂产生液相烧结作用,使得堇青石陶瓷的烧结温度从1 450℃降低到1 325℃。结果表明:(Mg1–xYx)2Al4Si5O18陶瓷在0≤x0.05范围内,以(Mg,Y)2Al4Si5O18固溶体形式存在;在0.05≤x0.25范围内,以Mg2Al4Si5O18/Y2Si2O7复相陶瓷形式存在。Y3+能够改善(Mg1–xYx)2Al4Si5O18陶瓷的颗粒尺寸分布,并使陶瓷的气孔率降低。(Mg1–xYx)2Al4Si5O18陶瓷的相对介电常数由x=0的6.15提高到x=0.05的6.31;然后逐渐降低至x=0.25的5.90。品质因数Qf值由x=0的33 000 GHz提高到x=0.05的41 000 GHz,然后降低至x=0.25的24 000 GHz。谐振频率温度系数(0.05≤x0.25)值从–32×10–6/℃提高到–24×10–6/℃。 相似文献
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微波介质陶瓷及其展望 总被引:7,自引:0,他引:7
综述了微波介质陶瓷材料的特性和发展现状,介绍了几种重要的微波介质陶瓷体系,讨论了微波介质陶瓷性能的影响因素,指出了改善其性能的途径和微波介质陶瓷的预期进展。 相似文献
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Structure‐Dependent Microwave Dielectric Properties and Middle‐Temperature Sintering of Forsterite (Mg1–xNix)2SiO4 Ceramics 下载免费PDF全文
Chen Zhang Ruzhong Zuo Jian Zhang Yang Wang 《Journal of the American Ceramic Society》2015,98(3):702-710
The crystal structure, microstructure, and microwave dielectric properties of forsterite‐based (Mg1–xNix)2SiO4 (x = 0.02–0.20) ceramics were systematically investigated. All samples present a single forsterite phase of an orthorhombic structure with a space group Pbnm except for a little MgSiO3 secondary phase as x > 0.08. Lattice parameters in all axes decrease linearly with increasing Ni content due to the smaller ionic radius of Ni2+ compared to Mg2+. The substitution of an appropriate amount of Ni2+ could greatly improve the sintering behavior and produce a uniform and closely packed microstructure of the Mg2SiO4 ceramics such that a superior Q × f value (152 300 GHz) can be achieved as x = 0.05. The τf value was found to increase with increasing A‐site ionic bond valences. In addition, various additives were used as sintering aids to lower the sintering temperature from 1500°C to the middle sintering temperature range. Excellent microwave dielectric properties of εr~6.9, Q × f~99800 GHz and τf~?50 ppm/°C can be obtained for 12 wt% Li2CO3‐V2O5‐doped (Mg0.95Ni0.05)2SiO4 ceramics sintered at 1150°C for 4 h. 相似文献
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本介绍了显微结构中的一些主要因素对微波介质陶瓷性能的影响;重点分析了晶粒-主晶相、玻璃相、气孔以及缺陷对微波介质陶瓷性能的影响;通过选择适当的工艺方法,如掺杂、湿化学合成方法等,实现陶瓷结构的致密、均匀,从而提高陶瓷体的微波性能。 相似文献
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微波介质陶瓷的研究进展 总被引:1,自引:0,他引:1
综述了微波介质陶瓷材料的特性和发展现状,给出了多数目前已经研究的微波陶瓷体系及其性能,阐述了其制备方法,提出了改善其性能的途径和微波介质陶瓷的预期进展. 相似文献
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The sol-gel method is used to obtain highly dispersed sintering-active forsterite powders. These powders were used to produce sufficiently strong and dense ceramics without additives at a firing temperature of 1350°C, however, full sintering of forsterite is hampered by intense recrystallization. 相似文献
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Xiao-Jun Kuang Hai-Ting Xia Fu-Hui Liao Chun-Hai Wang Lei Li Xi-Ping Jing Zong-Xi Tang 《Journal of the American Ceramic Society》2007,90(10):3142-3147
Two kinds of solid solution systems of Ta-doped MgTiO3 were identified by X-ray diffraction, which can be represented by the formulae MgTi1− x (Mg1/3 Ta2/3 ) x O3 (0≤ x <0.5) and MgTi1− x Ta x O3 (0≤ x <0.05). The conductivity and microwave dielectric loss for the two solid solution systems were examined by AC impedance and microwave resonator measurements, respectively. In the system MgTi1− x (Mg1/3 Ta2/3 ) x O3 , the mechanism for the solid solution formation is the isovalent substitution of for Ti4+ . In the system MgTi1− x Ta x O3 , the doping mechanism is the aliovalent substitution of Ta5+ for Ti4+ , where for a small amount Ta doping, the oxygen vacancies formed during the high-temperature preparation are filled by an extra oxygen introduced from Ta2 O5 and further Ta doping leads to an increase in the contents of and electrons, which was consistent with conductivity measurements. In both systems, the Q × f values improved, e.g., ∼17% for the isovalent substitution at x =0.08 and ∼10% for the aliovalent substitution at x =0.02. The filling oxygen vacancy and the substitution of Ta/Mg for Ti may contribute to the improvement of Q × f values for both systems. 相似文献
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采用传统固相反应法制备了Mg4(Nb2-xSbx)O9陶瓷,研究了该材料的烧结性能、物相结构、显微组织和微波介电性能.X射线衍射结果显示,在x小于或等于1.6的范围内,形成了具有α-Al2O3刚玉型晶体结构的连续固溶体,晶轴长度和晶胞体积均随着锑含量的增加而降低.在x等于2.0时,Mg4Sb2O9的物相结构发生了变化,晶轴长度和晶胞体积也发生了突变.当0.4≤x≤O.8时,陶瓷的烧结温度从1400℃降低到了1300℃;而当x≥1.2后,陶瓷的烧结性能和微波介电性能均降低.在1300℃,5h的烧结条件下,Mg4(Nb1.6Sb0.4)O9陶瓷的微波介电常数(εr)为12.26,Q·f为168450 GHz. 相似文献
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Denesh C. Dube Rudolf Zurmuhlen rew Bell Nava Setter Wolfram Wersing 《Journal of the American Ceramic Society》1997,80(5):1095-1100
The postresonator method proposed by Hakki and Coleman for the measurement of dielectric properties of solids in the microwave region is reexamined. Based on the experiments performed around 10 GHz, the limitations of the method in loss determination for materials with tan δ, 5 × 10−4 are outlined. Alternative techniques for studying high- Q materials are described. Loss measurements performed on well-prepared ceramics have been used to draw comparisons among these techniques. Some of the experimental findings are new and are reported for the first time. 相似文献