共查询到20条相似文献,搜索用时 15 毫秒
1.
Yih-Chien Chen Yen-Nien Wang Ruei-Yang Syu 《Journal of Materials Science: Materials in Electronics》2016,27(5):4259-4264
The microwave dielectric properties of Ba2MgWO6 ceramics were investigated with a view to the use of such ceramics in mobile communication. Ba2MgWO6 ceramics were prepared using the conventional solid-state method with various sintering temperatures. Dielectric constants (? r ) of 16.8–18.2 and unloaded quality factor (Q u × f) of 7000–118,200 GHz were obtained at sintering temperatures in the range 1450–1650 °C for 2 h. A maximum apparent density of 6.76 g/cm3 was obtained for Ba2MgWO6 ceramic, sintered at 1650 °C for 2 h. A dielectric constant (? r ) of 18.4, an unloaded quality factor (Q u × f) of 118,200 GHz, and a temperature coefficient of resonant frequency (τ f ) of ?34 ppm/°C were obtained when Ba2MgWO6 ceramics were sintered at 1650 °C for 2 h. 相似文献
2.
Chunchun Li Wangxi Wen Huaicheng Xiang Liang Fang Yihua Sun 《Journal of Materials Science: Materials in Electronics》2018,29(3):1907-1913
Crystal structure and dielectric properties of Zn3Mo2O9 ceramics prepared through a conventional solid-state reaction method were characterized. XRD and Raman analysis revealed that the Zn3Mo2O9 crystallized in a monoclinic crystal structure and reminded stable up to1020 °C. Dense ceramics with high relative density (~ 92.3%) were obtained when sintered at 1000 °C and possessed good microwave dielectric properties with a relative permittivity (ε r ) of 8.7, a quality factor (Q?×?f) of 23,400 GHz, and a negative temperature coefficient of resonance frequency (τ f ) of around ??79 ppm/°C. With 5 wt% B2O3 addition, the sintering temperature of Zn3Mo2O9 ceramic was successfully lowered to 900 °C and microwave dielectric properties with ε r ?=?11.8, Q?×?f?=?20,000 GHz, and τ f = ??79.5 ppm/°C were achieved. 相似文献
3.
The effects of CuO–Bi2O3–V2O5 additions on the sintering temperature and the microwave dielectric properties of MgTiO3 ceramics were investigated systematically. The CuO–Bi2O3–V2O5 (CuBiV) addition significantly lowered the densification temperature of MgTiO3 ceramics from 1400 °C to about 900 °C, which is due to the formation of the liquid-phase of BiVO4 and Cu3(VO4)2 during sintering. The saturated dielectric constant (εr) increased, the maximum quality factor (Qf) values decreased and the temperature coefficient of resonant frequency (τf) shifted to a negative value with the increasing CuBiV content, which is mainly attributed to the increase of the second
phase BiVO4. MgTiO3 ceramics with 6 wt.% CuBiV addition sintered at 900 °C for 2 h have the excellent microwave dielectric properties: ε r= 18.1, Qf = 20300 GHz and τf = −57 ppm/ °C. 相似文献
4.
Hong-Tie Soong Cheng-Hsing Hsu Cheng-Liang Huang Ming-Ta Kuo 《Journal of Materials Science》2007,42(7):2393-2398
The microwave dielectric properties and the microstructures of Sm(Co1/2Ti1/2)O3 ceramics with B2O3 additions (0.25 and 0.5 wt%) prepared by conventional solid-state route have been investigated. The prepared Sm(Co1/2Ti1/2)O3 exhibited a mixture of Co and Ti showing 1:1 order in the B-site. Doping with B2O3 (up to 0.5 wt%) can effectively promote the densification of Sm(Co1/2Ti1/2)O3 ceramics with low sintering temperature. It is found that Sm(Co1/2Ti1/2)O3 ceramics can be sintered at 1,260 °C due to the grain boundary phase effect of B2O3 addition. At 1,290 °C, Sm(Co1/2Ti1/2)O3 ceramics with 0.5 wt% B2O3 addition possess a dielectric constant (ε
r) of 27.7, a Q × f value of 33,600 (at 9 GHz) and a temperature coefficient of resonant frequency (τf) of −11.4 ppm/ °C. The B2O3-doped Sm(Co1/2Ti1/2)O3 ceramics can find applications in microwave devices requiring low sintering temperature. 相似文献
5.
Ping Zhang Lu Liu Yonggui Zhao Mi Xiao 《Journal of Materials Science: Materials in Electronics》2017,28(8):5802-5806
The Li3Mg2NbO6 ceramics doped with ZnO-B2O3-SiO2 (ZBS) additives were synthesized via the conventional solid-state reaction process. The influence of ZBS additives on phase composition, sintering behavior, microstructure and microwave dielectric properties of Li3Mg2NbO6 ceramics were investigated in detail. The XRD patterns showed that the sintered specimen presented a single phase and no secondary phase appeared. We found that proper amount of ZBS additives could significantly reduce the sintering temperature from 1250 to 925?°C and promote the densification of Li3Mg2NbO6 ceramics. The εr and Q?×?f value were strongly affected by bulk density and grain size, respectively. As ZBS content increased, the τf value shifted toward negative direction. In summary, excellent microwave dielectric properties of εr?~?14.84, Q?×?f?~?73,987 GHz, τf?~??16.05 ppm/°C could be obtained in 0.5 wt.% ZBS modified sample when sintered at 925?°C for 4 h. Furthermore, the material was compatible with Ag electrode, demonstrating that it would be a promising candidate material for LTCC application. 相似文献
6.
Wen-Cheng Tzou Chao-Chin Chan Ping-Shou Cheng Cheng-Fu Yang 《Journal of Materials Science》2005,40(17):4711-4714
7.
Wang-Suo Xia Fei Jin Mei Wang Xin Wang Guo-Ying Zhang Li-Wei Shi 《Journal of Materials Science: Materials in Electronics》2016,27(2):1100-1104
ZnTa2O6 ceramics with various amount of Al2O3 additive were synthesized by a conventional mixed-oxide route. The grain growth of ZnTa2O6 ceramics was accelerated with Al2O3 additive. However, excessive addition (>1.0 wt%) of Al2O3 leaded to abnormal grain growth. With Al2O3 addition, the Al2O3 additive did not solubilized into ZnTa2O6 structure but resulted in forming the second phase. The Al2O3 addition resulted in the lower sintering temperature of ZnTa2O6 ceramics and improved microwave dielectric properties. The dielectric constant (εr) of the samples did not change much and ranged from 32.41 to 34.33 with different amount of Al2O3 addition. The optimized quality factor (Q × f) was higher than 70,000 GHz as a result of the denser ceramics. The temperature coefficient of resonant frequency (τ f ) of the doped ZnTa2O6 ceramics could be optimized to near-zero. 相似文献
8.
A. G. Belous O. V. Ovchar A. V. Kramarenko Bostjan Jancar Jana Bezjak Danilo Suvorov 《Inorganic Materials》2010,46(5):529-533
Polycrystalline nonstoichiometric Ba(Co1/3Nb2/3)O3 (BCN) materials have been synthesized and investigated. Deviations from stoichiometry have been shown to lead to the formation
of crystalline Ba6CoNb9O30 (barium deficiency) and Ba8CoNb6O24 (cobalt deficiency). The effect of phase composition on the microwave dielectric properties of BCN has been studied. The
results demonstrate that the dielectric properties of BCN-based materials can be tuned by varying cobalt content. The materials
obtained are high-Q microwave dielectrics with temperature-stable properties. 相似文献
9.
10.
H. L. Pan M. T. Liu M. F. Li F. Ling H. T. Wu 《Journal of Materials Science: Materials in Electronics》2018,29(2):999-1003
Li6Mg7Ti3O16 ceramics were prepared by the conventional solid-state method with 1–5 wt% LiF as the sintering aid. Effects of LiF additions on the phase compositions, sintering characteristics, micro-structures and microwave dielectric properties of Li6Mg7Ti3O16 ceramics were investigated. The LiF addition could effectively lower the sintering temperature of Li6Mg7Ti3O16 ceramics from 1550 to 900 °C. For different LiF-doped compositions, the optimum dielectric permittivity (ε r ) and quality factor (Q·f) values first increased and then decreased with the increase of LiF contents, whereas the temperature coefficient of resonant frequency (τ f ) fluctuated between ??14.39 and ??8.21 ppm/°C. Typically, Li6Mg7Ti3O16 ceramics with 4 wt% LiF sintered at 900 °C exhibited excellent microwave dielectric properties of ε r ?=?16.17, Q·f?=?80,921 GHz and τ f ?=???8.21 ppm/°C, which are promising materials for the low temperature co-fired ceramics applications. 相似文献
11.
Yang Wu Ruzhong Zuo Jinjin Zhang Yuanyuan Zhou Zhenxing Yue 《Journal of Materials Science: Materials in Electronics》2011,22(2):106-110
The effect of CuO and B2O3 co-doping on the sintering behavior, microstructure and microwave dielectric properties of tungsten bronze type Ba4Nd9.3Ti18O54 (BNT) ceramics has been investigated by means of a traditional solid-state mixed oxide route. On the one hand, it was indicated
that the mixture of CuO and B2O3 is an effective sintering aid for BNT matrix compositions owing to the existence of a low-temperature eutectic reaction.
On the other hand, it was found that the addition of CuO and B2O3 has an obvious effect on microwave dielectric properties of BNT ceramics, depending on the amount of sintering aids, the
sample density and microstructure. The liquid phases from sintering aids can promote densification, but simultaneously induce
grain growth which tends to decrease the sintering driving force. BNT ceramics doped with 3 wt% CuO–B2O3 mixture can be well sintered at 950°C for 4 h and still exhibit relatively good microwave dielectric properties. 相似文献
12.
13.
Zixing Wang Changlai Yuan Baohua Zhu Qin Feng Fei Liu Lei Miao Changrong Zhou Guohua Chen 《Journal of Materials Science: Materials in Electronics》2018,29(3):1817-1822
A novel microwave dielectric ceramics Bi(Sc1/3Mo2/3)O4 with low firing temperature were prepared via the solid reaction method. The specimens have been characterized using scanning electron microscopy, X-ray diffraction, Raman spectroscopy and DC conductivity. The Bi(Sc1/3Mo2/3)O4 ceramics showed B-site ordered Scheelite-type structure with space group C2/c. Raman analysis indicated that prominent bands were attributed to the normal modes of vibration of MoO4 2? tetrahedra. The dielectric loss of Bi(Sc1/3Mo2/3)O4 ceramics can be depended strongly the bulk conductivity by DC measurement. The superior microwave dielectric properties are achieved in the Bi(Sc1/3Mo2/3)O4 ceramic sintered at 875 °C/4 h, with dielectric constant?~?25, Q?×?f ~?51,716 GHz at 6.4522 GHz and temperature coefficient of resonance frequency ~???70.4 ppm/°C. It is a promising microwave dielectric material for low-temperature co-fired ceramics technology. 相似文献
14.
Shantala D. Patil S. C. Raghavendra M. Revansiddappa P. Narsimha M. V. N. Ambika Prasad 《Bulletin of Materials Science》2007,30(2):89-92
Conducting polyaniline/cobaltous oxide composites have been synthesized using in situ deposition technique by placing fine graded/cobaltous oxide in polymerization mixture of aniline. The a.c. conductivity and
dielectric properties are studied by sandwiching the pellets of these composites between the silver electrodes. It is observed
that the values of conductivities increase up to 30 wt% of cobaltous oxide in polyaniline and decrease thereafter. Initial
increment in conductivity is due to extended chain length of polyaniline where polarons possess sufficient energy to hop between
favourable sites. Beyond 30 wt% of cobaltous oxide in polyaniline, blocking of charge carriers takes place reducing the conductivity
values. It can be noted that the value of dielectric constant increases up to 10 wt% of cobaltous oxide. Thereafter, it decreases
up to 30 wt% of cobaltous oxide and again increases up to 40 wt% of cobaltous oxide and decreases thereafter. The observed
behaviour is attributed to the variation of a.c. conductivity. And it is observed that the dielectric loss increases up to
10 wt% of cobaltous oxide in polyaniline, decreases to a lower value of 20 wt% of cobaltous oxide and increases to 35 wt%
and thereafter decreases. These values go in accordance with the values of dielectric constant. The results obtained for these
composites are of greater scientific and technological importance. 相似文献
15.
Dong-Xiang Zhou Fei Sun Yun-Xiang Hu Qiu-Yun Fu Gang Dou 《Journal of Materials Science: Materials in Electronics》2012,23(5):981-989
The Mg3B2O6 ceramics with lithium magnesium zinc borosilicate (LMZBS) glass were prepared at a lower sintering temperature. The effects of the glass addition on the densification, phase development, microstructure and microwave dielectric properties of the Mg3B2O6 ceramics were investigated. The addition of LMZBS glass improved the densification and lowered the sintering temperature of Mg3B2O6 ceramics from 1,300 to 950 °C. X-ray diffraction patterns showed that Mg3B2O6 transformed into Mg2B2O5 and a new phase, Li2ZnSiO4, crystallized from the glass phase. Because of the high dielectric performance of these phases, Mg3B2O6 mixed with 55 wt% LMZBS sintered at 950 °C for 3 h had εr = 6.8, Q × f = 50,000 GHz, and τf = ?64 ppm/°C at 7.28 GHz. The chemical compatibility of ceramic-glass composites with Ag was also investigated for LTCC. 相似文献
16.
Wang-Suo Xia Lan-Yang Zhang Ying Wang Jun-Ting Zhang Rong-Rong Feng Li-Wei Shi 《Journal of Materials Science: Materials in Electronics》2017,28(24):18437-18441
Microwave dielectric ceramics CuO–modified MgZrTa2O8 were synthesized by the conventional solid-state reaction method. The effects of CuO additives on the sintering characteristics and microwave dielectric properties have been investigated. With CuO addition, the sintering temperature of MgZrTa2O8 ceramics can be effectively lowered from 1475 to 1375 °C without decreasing its dielectric properties obviously and the temperature coefficient of the resonant frequency of MgZrTa2O8 ceramics have been optimized to near-zero. The crystalline phase exhibited a wolframite crystal structure and no second phase was detected at low addition levels. The grain growth of CuO–modified MgZrTa2O8 ceramics was accelerated due to liquid phase effect. The relative dielectric constants (εr) were correlated with apparent density and were not significantly different for all levels of CuO concentration. The quality factors (Q?×??) and temperature coefficient of resonant frequency (τ?), which were strongly dependent on the CuO concentration, were analyzed by the grain size and the dielectric constant respectively. A best Q?×?? value of 116400 GHz and τ? value of ?6.19 ppm/℃ were obtained for specimen with 0.05 wt% CuO addition at 1375 °C. 相似文献
17.
Xiang Dong Haiqing Wang Zhongqiu Hua Shujie Peng Liang Dong Yu Wang 《Journal of Materials Science: Materials in Electronics》2012,23(6):1210-1214
Tungsten trioxide (WO3) doped with cobalt sesquioxide (Co2O3) was prepared by a conventional mixed oxide processing route and the thermoelectric properties were studied from 300 up to
1,000 K. The addition of Co2O3 to WO3 resulted in an increase in both the grain size and porosity, indicating that Co2O3 promotes the grain grown of WO3. The magnitude of the electrical conductivity (σ) and the absolute value of the Seebeck coefficient (|S|) depended strongly on the Co2O3 content. As for the power factor (σS
2
), the 5.0 mol% sample has the maximum value of the power factor which is 0.12 μWm−1K−2 at 873 K. 相似文献
18.
Jie Su Xiaomei Lu Chao Zhang Junting Zhang Song Peng Xiaobo Wu Kangli Min Fengzhen Huang Jinsong Zhu 《Journal of Materials Science》2011,46(10):3488-3492
Ho3Fe5O12 ceramics were fabricated by the solid-state reaction method. The results revealed an increase of the grain size, dielectric
constant, and dielectric loss, while a decrease of the remnant magnetization and coercive field with increasing sintering
temperature. A dielectric relaxation behavior was observed, which might be associated with the charge carrier hopping between
Fe2+ and Fe3+. A cole–cole fitting to loss peaks revealed a dependence of the activation energy and the broaden factor on the relative density of the
samples. Furthermore, at appropriate frequencies, the 1250 °C-sintered samples showed high dielectric constant, low dispassion,
and good temperature stability around room temperature. 相似文献
19.
Haibo Yang Jingjing Dai Ying Lin Ning Han Xiao Liu Jingjing Wang 《Journal of Materials Science: Materials in Electronics》2017,28(15):10853-10861
Polyaniline (PANI)/CoFe2O4/Ba3Co2Fe24O41 composite was prepared by an in-situ polymerization method. The phase structure, morphology and magnetic properties of the as-prepared PANI/CoFe2O4/Ba3Co2Fe24O41 composite were characterized by XRD, FT-IR, SEM, TEM, and VSM, respectively. The microwave absorption properties of the composite were investigated by using a vector network analyzer in the 2–18 GHz frequency range. The results show that the maximum reflection loss value of the PANI/CoFe2O4/Ba3Co2Fe24O41 composite reaches ?30.5 dB at 10.5 GHz with a thickness of 3 mm and the bandwidth of reflection loss below ?10 dB reaches up to 1.2 GHz. The excellent microwave absorption properties of the as-prepared PANI/CoFe2O4/Ba3Co2Fe24O41 composite due to the enhanced impedance match between dielectric loss and magnetic loss. 相似文献
20.
Xiao Chun Zhou Lu Ping Zhong Qiu Ping Liu Ren Yun Kuang Hong Mei Chen 《Inorganic Materials》2009,45(11):1295-1298
New red emitting phosphors, Ca3(VO4)2:Eu3+,Bi3+, Ca3((P,V)O4)2:Eu3+ were synthesized by low temperature solid-state reaction and characterized by X-ray diffraction, scanning electron microscopy, photoluminescence spectra and Fourier transform infrared spectroscopy. The results show that the red emission located at about 613 nm was ascribed to 5 D 0-7 F 2 transition of Eu3+. The effect of by Bi doping and by P doping was also investigated systematically. 相似文献