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1.
Nonstoichiometric Mg2 SiO4 forsterite dielectric ceramics with various Mg/Si ratios ( R =2.025, 2.05, and 2.2) were prepared and characterized. The appearance of a MgSiO3 secondary phase could be effectively suppressed by adjusting the nonstoichiometry, and a single-phase forsterite structure was obtained in the present ceramics with Mg/Si ratios of 2.025 and 2.05. The microwave dielectric characteristics were significantly improved in the nonstoichiometric Mg2 SiO4 ceramics on eliminating the MgSiO3 secondary phase, where an enhanced Q × f value and a suppressed temperature coefficient of resonant frequency λ f were obtained. The best microwave characteristics were achieved in the nonstoichiometric forsterite ceramics with an Mg/Si ratio of 2.05: ɛ r =7.5, Q × f =114 730 GHz, and λ f =−59 ppm/°C. 相似文献
2.
Mi-Ri Joung Jin-Seong Kim Myung-Eun Song Sahn Nahm Jong-Hoo Paik Byung-Hyun Choi 《Journal of the American Ceramic Society》2009,92(7):1621-1624
The formation process and microwave dielectric properties of the Mg2 V2 O7 ceramics were investigated. The MgV2 O6 phase that was formed at around 450°C interacted with remnant MgO above 590°C to form a homogeneous monoclinic Mg2 V2 O7 phase. Finally, this monoclinic Mg2 V2 O7 phase was changed to a triclinic Mg2 V2 O7 phase for the specimen fired at 800°C. Sintering at 950°C for more than 5 h produced high-density triclinic Mg2 V2 O7 ceramics. In particular, the Mg2 V2 O7 ceramics sintered at 950°C for 10 h exhibited the good microwave dielectric properties of ɛr =10.5, Q × f =58 275 GHz, and τf =−26.9 ppm/°C. 相似文献
3.
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
4.
Mi-Ri Joung Jin-Seong Kim Myung-Eun Song Jae-Hong Choi Jong-Woo Sun Sahn Nahm Jong-Hoo Paik Byung-Hyun Choi 《Journal of the American Ceramic Society》2009,92(9):2151-2154
Li2 CO3 was added to Mg2 V2 O7 ceramics in order to reduce the sintering temperature to below 900°C. At temperatures below 900°C, a liquid phase was formed during sintering, which assisted the densification of the specimens. The addition of Li2 CO3 changed the crystal structure of Mg2 V2 O7 ceramics from triclinic to monoclinic. The 6.0 mol% Li2 CO3 -added Mg2 V2 O7 ceramic was well sintered at 800°C with a high density and good microwave dielectric properties of ɛ r =8.2, Q × f =70 621 GHz, and τf =−35.2 ppm/°C. Silver did not react with the 6.0 mol% Li2 CO3 -added Mg2 V2 O7 ceramic at 800°C. Therefore, this ceramic is a good candidate material in low-temperature co-fired ceramic multilayer devices. 相似文献
5.
The microwave dielectric properties and the microstructures of (Mg1− x Co x )2 TiO4 ceramics prepared by the conventional solid-state route were investigated. Lattice parameters were also measured for specimens with different x . The formation of solid solution (Mg1− x Co x )2 TiO4 ( x =0.02–0.1) was confirmed by the X-ray diffraction patterns, energy dispersive X-ray analysis, and the lattice parameters measured. By increasing x from 0 to 0.05, the Q × f of the specimen can be tremendously boosted from 150 000 GHz to a maximum of 286 000 GHz. A fine combination of microwave dielectric properties (ɛr ∼15.7, Q × f ∼286 000 GHz at 10.4 GHz, τf ∼−52.5 ppm/°C) was achieved for (Mg0.95 Co0.05 )2 TiO4 ceramics sintered at 1390°C for 4 h. Ilmenite-structured (Mg0.95 Co0.05 )TiO3 was detected as a second phase. The presence of the second phase would cause no significant variation in the dielectric properties of the specimen because it possesses compatible properties compared with that of the main phase. In addition, only a small deviation in the dielectric properties was monitored for specimens with x =0.04–0.05 at 1360°–1420°C. It not only provides a wide process window but also ensures an extremely reliable material proposed as a very promising dielectric for low-loss microwave and millimeter wave applications. 相似文献
6.
Jin-Seong Kim Ngoc-Huan Nguyen Myung-Eun Song Jong-Bong Lim Dong-Soo Paik Sahn Nahm Jong-Hoo Paik Byung-Hyun Choi Soon-Jae Yu 《International Journal of Applied Ceramic Technology》2009,6(5):581-586
Bi2 O3 was added to a nominal composition of Zn1.8 SiO3.8 (ZS) ceramics to decrease their sintering temperature. When the Bi2 O3 content was <8.0 mol%, a porous microstructure with Bi4 (SiO4 )3 and SiO2 second phases was developed in the specimen sintered at 885°C. However, when the Bi2 O3 content exceeded 8.0 mol%, a liquid phase, which formed during sintering at temperatures below 900°C, assisted the densification of the ZS ceramics. Good microwave dielectric properties of Q × f =12,600 GHz, ɛr =7.6, and τf =−22 ppm/°C were obtained from the specimen with 8.0 mol% Bi2 O3 sintered at 885°C for 2 h. 相似文献
7.
Synthesis of BaCu(B2 O5 ) Ceramics and their Effect on the Sintering Temperature and Microwave Dielectric Properties of Ba(Zn1/3 Nb2/3 )O3 Ceramics 总被引:1,自引:0,他引:1
Min-Han Kim Jong-Bong Lim Jae-Chul Kim Sahn Nahm Jong-Hoo Paik Jong-Hee Kim Kyeong-Soon Park 《Journal of the American Ceramic Society》2006,89(10):3124-3128
BaCu(B2 O5 ) ceramics were synthesized and their microwave dielectric properties were investigated. BaCu(B2 O5 ) phase was formed at 700°C and melted above 850°C. The BaCu(B2 O5 ) ceramic sintered at 810°C had a dielectric constant (ɛr ) of 7.4, a quality factor ( Q × f ) of 50 000 GHz and a temperature coefficient of resonance frequency (τf ) of −32 ppm/°C. As the BaCu(B2 O5 ) ceramic had a low melting temperature and good microwave dielectric properties, it can be used as a low-temperature sintering aid for microwave dielectric materials for low temperature co-fired ceramic application. When BaCu(B2 O5 ) was added to the Ba(Zn1/3 Nb2/3 )O3 (BZN) ceramic, BZN ceramics were well sintered even at 850°C. BaCu(B2 O5 ) existed as a liquid phase during the sintering and assisted the densification of the BZN ceramic. Good microwave dielectric properties of Q × f =16 000 GHz, ɛr =35, and τf =22.1 ppm/°C were obtained for the BZN+6.0 mol% BaCu(B2 O5 ) ceramic sintered at 875°C for 2 h. 相似文献
8.
Jin-Seong Kim Ngoc-Huan Nguyen Jong-Bong Lim Dong-Soo Paik Sahn Nahm Jong-Hoo Paik Jong-Hee Kim Hwack-Joo Lee 《Journal of the American Ceramic Society》2008,91(2):671-674
B2 O3 was added to nominal composition Zn1.8 SiO3.8 (ZS) ceramics to decrease their sintering temperature for application to low-temperature cofired ceramic (LTCC) devices. B2 O3 reacted with SiO2 to form a liquid phase containing SiO2 and B2 O3 . The composition and melting temperature of the liquid phase depended on the sintering temperature and the B2 O3 content. The specimen containing 20.0 mol% of B2 O3 sintered at 900°C exhibited high microwave dielectric properties of Q × f =53 000 GHz, ɛ r =5.7, and τf =−16 ppm/°C, confirming the promising potential of the B2 O3 -added ZS ceramics as candidate materials for the LTCC devices. 相似文献
9.
Low-loss ceramics having the chemical formula Mg2 (Ti1− x Sn x )O4 for x ranging from 0.01 to 0.09 have been prepared by the conventional mixed oxide route and their microwave dielectric properties have been investigated. X-ray powder diffraction patterns indicate the corundum-structured solid solutions for the prepared compounds. In addition, lattice parameters, which linearly increase from 8.4414 to 8.4441 Å with the rise of x from 0.01 to 0.09, also confirm the forming of solid solutions. By increasing x from 0.01 to 0.05, the Q × f of the specimen can be tremendously boosted from 173 000 GHz to a maximum 318 000 GHz. A fine combination of microwave dielectric properties (ɛr ∼15.57, Q × f ∼318 000 GHz at 10.8 GHz, τf ∼−45.1 ppm/°C) was achieved for Mg2 (Ti0.95 Sn0.05 )O4 ceramics sintered at 1390°C for 4 h. Ilmenite-structured Mg(Ti0.95 Sn0.05 )O3 (ɛr ∼16.67, Q × f ∼275 000 GHz at 10.3 GHz, τf ∼−53.2 ppm/°C) was detected as a second phase. The presence of the second phase, however, would cause no significant variation in the dielectric properties of the specimen, because the second phase properties are very similar to the primary phase. These unique properties, in particular, low ɛr and high Q × f , can be utilized as a very promising dielectric material for ultra-high-frequency applications. 相似文献
10.
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
11.
X. M. Chen D. Liu R. Z. Hou X. Hu X. Q. Liu 《Journal of the American Ceramic Society》2004,87(12):2208-2212
Ca(Zn1/3 Nb2/3 )O3 microwave dielectric ceramics were prepared using a solid-state reaction process, and their microwave dielectric properties were evaluated as functions of sintering and postdensification annealing conditions. The relationship between microwave dielectric properties and processing was interpreted through the variation of microstructures. The dielectric constant showed slight variation with sintering and annealing conditions, but the Q × f value increased at first and then decreased with increased sintering temperature, and annealing in oxygen indicated significant improvement in Q × f , especially for the specimens sintered at higher temperatures. The good microwave dielectric properties were obtained in the ceramics sintered at 1225°C in air for 3 h and annealed at 1100°C in oxygen for 8 h: ɛ= 34.1, Q × f = 15 890 GHz, τf =−48 ppm/°C. 相似文献
12.
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
13.
The sintering behavior and dielectric properties of Bi3 NbO7 ceramics prepared by the high-energy ball milling (HEM) method and conventional mixed oxides method with V2 O5 addition were investigated. All the samples were sintered between 840° and 960°C. For the ceramics prepared by the mixed oxides method, the pure tetragonal Bi3 NbO7 phase formed without any cubic phase. With changing sintering temperature, the dielectric constant ɛr lies between 79 and 92, while the Q × f values are between 300 and 640 GHz. The samples sintered at 870°C have the best microwave dielectric properties with ɛr =79, Q × f =640 GHz, and the temperature coefficients of resonant frequency τf between 0 and −20 ppm/°C. For the ceramics prepared by the HEM, a pure cubic phase was obtained. The ɛr changes between 78 and 80 and Q × f were between 200 and 290 GHz. 相似文献
14.
M. A. BREDIG 《Journal of the American Ceramic Society》1950,33(6):188-192
Therecentobservation of orthorhombic α'-Ca2 Si04 (bredigite) at all temperatures between about 850° and 1450°C. leads to a rational interpretation of the polymorphism of this substance, which is very satisfactory from the crystal-chemical point of view. The so-called β phase, of as yet unknown, complex structure, exists only meta-stably, and not above but below about 675°C, where γ is the stable phase. The monotropic β phase forms on cooling from α'near 675°C. as the result of the inhibition of the α'→γ inversion, at 850°C. The inhibition is caused by the need for a considerable atomic rearrangement and a 12% volume increase which accompanies the change of the coordinations CaO2 and CaOlo, in α', to CaO6 , in γ. Among the solid phase equilibria with, Mg2 SiO4 and Ca3 (PO4 )2 , unlimited solid solubility between γ-Ca2 SiO4 and Mg2 SiO4 is predicted, whereas the solubility of Mg2 SiO4 is a limited one in α'and still more so in a-Ca2 SiO4 , as a result of the substitution, for calcium, of the smaller magnesium. 相似文献
15.
Takahiro Takada Sea Fue Wang Shoko Yoshikawa Sei-Joo Jang Robert E. Newnham 《Journal of the American Ceramic Society》1994,77(7):1909-1916
The effect of glass addition on the properties of BaO–TiO2 -WO3 microwave dielectric material N-35, which has Q = 5900 and K = 35 at 7.2 GHz for samples sintered at 1360°C, was investigated. Several glasses including B2 O3 , SiO2 , 5ZnO–2B2 O3 , and nine other commercial glasses were selected for this study. Among these glasses, one with a 5 wt% addition of B2 O3 to N-35, when sintered at 1200°C, had the best dielectric properties: Q = 8300 and K = 34 at 8.5 GHz. Both Q and K increased with firing temperature as well as with density. The Q of N-35, when sintered with a ZnO–B2 O3 glass system, showed a sudden drop in the sintering temperature to about 1000°C. The results of XRD, thermal analysis, and scanning electron microscopy indicated that the chemical reaction between the dielectric ceramics and glass had a greater effect on Q than on the density. The effects of the glass content and the mixing process on the densification and microwave dielectric properties are also presented. Ball milling improved the densification and dielectric properties of the N-35 sintered with ZnO–B2 O3 . 相似文献
16.
Palaniappan Ravindranathan Sridhar Komarneni Amar S. Bhalla Rustum Roy 《Journal of the American Ceramic Society》1991,74(12):2996-2999
A solution sol-gel method has been developed to prepare 0.9Pb(Mg1/3 Nb2/3 )O3 -0.1PbTiO3 (0.9PMN-0.1PT) ceramics. During the processing the gel first converted to cubic pyrochlore phase at a calcination temperature of 600°C followed by the formation of pure perovskite phase at 775°C. The ceramics sintered at 1250°C for 4 h showed ≈98% of the theoretical density. The room-temperature dielectric constant of the pellets sintered at 1250°C showed a maximum value of 25035 at 1 kHz. Sintering studies at different temperatures revealed that the dielectric constant increased with increasing grain size in these ceramics. 相似文献
17.
Jae Chul Kim Min-Han Kim Jong-Bong Lim Sahn Nahm Jong-Hoo Paik Jong-Hee Kim 《Journal of the American Ceramic Society》2007,90(2):641-644
Re3 Ga5 O12 (Re: Nd, Sm, Eu, Dy, Yb, and Y) garnet ceramics were synthesized and their microwave dielectric properties were investigated for advanced substrate materials in microwave integrated circuits. The Re3 Ga5 O12 ceramics sintered at 1350°–1500°C had a high-quality factor ( Q × f ) ranging from 40 000 to 192 173 GHz and a low-dielectric constant (ɛr ) of between 11.5 and 12.5. They also exhibited a relatively stable temperature coefficient of resonant frequency (τf ) in the range of −33.7 to −12.4 ppm/°C. In particular, the Sm3 Ga5 O12 ceramics sintered at 1450°C exhibited good microwave dielectric properties of ɛr =12.4, Q × f =192 173 GHz, and τf =−19.2 ppm/°C. 相似文献
18.
Jian-Xi Tong Qi-Long Zhang Hui Yang Jia-Li Zou 《Journal of the American Ceramic Society》2007,90(3):845-849
The effects of LiF and ZnO–B2 O3 –SiO2 (ZBS) glass combined additives on phase composition, microstructures, and microwave dielectric properties of Ca[(Li1/3 Nb2/3 )0.84 Ti0.16 ]O3−δ (CLNT) ceramics were investigated. The LiF and ZBS glass combined additives lowered the sintering temperature of CLNT ceramics effectively from 1150° to 880°C. The main diffraction peaks of all the specimens split due to the coexistence of the non-stoichiometric phase (A) and stoichiometric phase (B), which all possess CaTiO3 -type perovskite structures. The transformation from A into B became accelerated with the increase of LiF or ZBS content. ZBS glass restrained the volatilization of lithium salt, which greatly affected the microstructures and microwave dielectric properties. CLNT ceramics with 2 wt% LiF and 3 wt% ZBS sintered at 900°C for 2 h show excellent dielectric properties: ɛr =34.3, Q × f =17 400 GHz, and τf =−4.6 ppm/°C. It is compatible with Ag electrodes, which makes it a promising ceramic for low-temperature cofired ceramics technology application. 相似文献
19.
Qun Zeng Wei Li Jian-lin Shi Jing-kun Guo 《Journal of the American Ceramic Society》2006,89(10):3305-3307
The effects of V2 O5 addition on the sintering behavior, microstructure, and the microwave dielectric properties of 5Li2 O–0.583Nb2 O5 –3.248TiO2 (LNT) ceramics have been investigated. With addition of low-level doping of V2 O5 (≤2 wt%), the sintering temperature of the LNT ceramics could be lowered down to around 920°C due to the liquid phase effect. A secondary phase was observed at the level of 2 wt% V2 O5 addition. The addition of V2 O5 does not induce much degradation in the microwave dielectric properties but lowers the τf value to near zero. Typically, the excellent microwave dielectric properties of ɛr =21.5, Q × f =32 938 GHz, and τf =6.1 ppm/°C could be obtained for the 1 wt% V2 O5 -doped sample sintered at 920°C, which is promising for application of the multilayer microwave devices using Ag as an internal electrode. 相似文献
20.
A new ultra low loss microwave dielectric ceramic, Mg(Sn0.05 Ti0.95 )O3 (MSnT), was found and investigated. The compounds were prepared by the conventional solid-state route, and sintered at 1360°–1480°C for 2–6 h. The investigations show that the MgTi2 O5 secondary phase was observed. Moreover, the dielectric properties were correlated with the formation second phase. The excellent microwave dielectric properties of Q × f =322 000 (GHz), ɛr =17.4, and τf =−54 ppm/°C were obtained from the new MSnT ceramics sintered at 1390°C for 4 h. 相似文献