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Microwave Dielectric Resonator Ceramics of High-Q Value for the 3G Mobile Communication Base Stations

Author: WangJun
Tutor: LvWenZhong
School: Huazhong University of Science and Technology
Course: Materials Physics and Chemistry
Keywords: The Ba Co, Zn 1/3Nb2/3O3 based ceramics Ion ordering degree Microwave dielectric properties
CLC: TQ174.756
Type: Master's thesis
Year: 2011
Downloads: 29
Quote: 0
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Abstract


Looking at the history and prospects of the development of the cause of China's 3G mobile communication for 3G mobile communication base station high-Q resonator ceramic Research to determine the Ba (Co, Zn) 1/3 Nb < sub> 2/3 O 3 -based ceramic object of this paper, the use of X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and network analyzer instrument system The recipe, sintering process, microstructure and microwave dielectric properties. First study of Ba 1-x Zn 1/3 Nb 2/3 O 3 (x = 0 < sup> 0 .02) the ceramic sintering characteristics, phase composition, ion orderly and microwave dielectric properties. The results showed that the right amount of Ba absence will not change the the Ba 1-x Zn 1/3 Nb 2/3 O 3 < / sub> (x = 0 0 .02) ceramic phase composition, but will significantly improve Ba 1-x Zn 1/3 Nb reduced by about 100 ° C 2/3 O 3 material sintering characteristics BZN ceramic sintering temperature can improve the ceramic cation ordering degree and Q × f value; x = 0.01, the the Ba 1-x Zn 1/3 the Nb 2/3 O 3 (x = 0.01) ceramic having the highest ionic degree of ordering, the samples were sintered at 1450 ℃ has a high Q × f value 66532GHz; on this basis, the system studied the of Ba 1-x Zn 1/3 the Nb 2/3 O 3 (x = 0.01) ceramic calcining temperature and cooling rate, and determined to achieve higher Q × f The values ??of the process parameters, which are 1100 ℃ and 5 ° C / h, the microwave dielectric properties: the ε r = 39.8, Q × f = 77719GHz the τ f = 24.5ppm / ℃. In the study on the basis of the absence of Ba Ba 0.99 (Co 1-x Zn x ) 1/3 the Nb 2/3 O 3 (x = 0 0 .8) sintering properties, phase composition, grain growth, cations sequence of degrees and microwave dielectric properties variation. With the increase of x Ba 0.99 (Co. 1-x ), the Zn x and 1/3 Nb < sub> 2/3 O 3 easier ceramic densely sintered, the dielectric constant is gradually increased, the temperature coefficient of resonant frequency is shifted to the positive direction; two-step sintering can significantly increase the density of the ceramic and Q × f value Ba 0.99 (Co. 1-x the Zn x ) and 1/3 Nb 2/3 O 3 (x = 0.2) ceramics sintered at 1490 ℃ second step can obtain a higher density and cationic degree of order, the ceramic has excellent microwave dielectric Performance: Q × f = 79852GHz the ε r = 33.1 the τ f = 2.6 ppm / ° C. For Ba 0.99 (Co 1-x Zn x ) 1/3 Nb 2/3 < / sub> O 3 the system ceramic, when x = 0.3, Ba 0.99 (Co 0.7 Zn 0.3 ) ceramic 2 can reduce 1/3 the Nb 2/3 O 3 ceramics mixed with the right amount of CeO sintering temperature, promote sintering, the CeO 2 doped gradually increasing the amount of cation ordering degree first and then decrease, when the samples sintered at 1500 ° C for two-step, CeO 2 doped amount 0.25wt.%, Ba , 0.99 (Co. 0.7 A Zn 0.3 ) 1/3 the Nb 2/3 O 3 ion ceramic has the highest degree of order, the ceramic has the most excellent microwave dielectric properties: ε r = 34.3, Q × f = 89966GHz, τ f = 4.7ppm / ℃. Meet the stoichiometric ratio of Ba (Co 0.7 Zn 0.3 ) 1/3 Nb 2/3 O < sub> 3 ceramics doped with an appropriate amount of CeO 2 can also be effective in promoting the sintering to improve the density of the ceramic, and with the doped CeO 2 increase of large ceramic cation ordering degree first and then decrease the when CeO 2 doping amount of 0.4wt.%, Ba (Co 0.7 Zn 0.3 ) 1/3 Nb 2/3 O 3 ceramic cation ordering degree, this time ceramics in 1500 ℃ under two-step sintering best microwave dielectric properties: the ε r = 33.3, Q × f = 100144GHz the τ f = 4.8 ppm / ° C. Ba (Co 1-x Zn x ) 1/3 Nb 2/3 O 3 < / sub> 0.4wt.? O 2 ceramic two-step sintering at 1490 ℃, the grain size as x increases gradually increasing its ion gradually increased degree of order, and then decreased is 0, when x = 0.4, Ba (Co 1-x Zn x ) 1/3 Nb 2/3 < / sub> O 3 0.4wt.? O 2 (x = 0.4) ceramics have the highest cationic degree of order, the ceramic microwave dielectric properties: ε r = 34.3, Q × f = 65330GHz, τ f = 8.9 ppm / ℃.

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