Effect of CeO2 on the sintering behaviour, cation order and properties of Ba3Co0.7Zn0.3Nb2O9 ceramics

Azough, Feridoon; Leach, C.; Freer, Robert

doi:10.1016/j.jeurceramsoc.2005.09.016

Cited by 37 publications

(32 citation statements)

References 13 publications

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“…This improvement of the Q f -value is explained by 1:2 cation ordering in accordance with the XRD data recorded on the surface of the post-sinter annealed ceramics (S1a and S2a), as shown in the small insert figure in Figures 3b and 5b, respectively. A similar result was previously reported which shows the increase of the Q f values as a consequence of cation ordering [9]. This Q f value of 123,700 GHz is higher than those obtained for the undoped and Al 2 O 3 -doped BCZN ceramics (Q f = 115,307 and 61,056 GHz, respectively), published recently [14,15], indicating that the Ba(Co 0.7 Zn 0.3 ) 1/3 Nb 2/3 O 3 materials are promising candidates for microwave device applications.…”

Section: Microwave Dielectric Propertiessupporting

confidence: 90%

“…No significant differences in dielectric properties were observed before and after polishing. This is due to their good microwave dielectric properties [9]. This observation suggests that the secondary phases of Ba 8 (Co,Zn) 1 Nb 6 O 24 and of Ba 5 Nb 4 O 15 seem to have no effect on the dielectric properties.…”

Section: Microwave Dielectric Propertiesmentioning

confidence: 96%

“…However, the dielectric properties of these ceramic materials are dependent on their density [8]. In addition, it is well known that BCZN-based ceramics are difficult to densify below 1450 ¥ C [9]. In order to improve the sinterability of BCZN ceramics, we have successfully used the aqueous mixing technique-assisted solid-state method for the preparation of Ba(Co 0.7 Zn 0.3 ) 1/3 Nb 2/3 O 3 powders, which were sintered at 1350 ¥ C for 30 h in air [10].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Post-Annealing on the Microstructure and Microwave Dielectric Properties of Ba(Co0.7Zn0.3)1/3Nb2/3O3 Ceramics

Itaalit¹,

Mouyane²,

Bernard³

et al. 2015

Applied Sciences

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Abstract:The effects of post-annealing on the crystal structure, microstructure, and microwave dielectric properties for Ba(Co 0.7 Zn 0.3 ) 1/3 Nb 2/3 O 3 ceramics were investigated. The as-prepared materials were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The microwave dielectric properties are measured at 6 GHz using a network analyzer. Ba 5 Nb 4 O 15 and/or Ba 8 (Co,Zn) 1 Nb 6 O 24 secondary phases were found on the surface according to sintering conditions due to volatilization of some Zn and Co elements. The experimental results show that the beneficial effect of the annealing steps to improved the microwave dielectric properties. Excellent microwave dielectric properties were achieved for the coarse-grained microstructures by a higher sintering temperature and with a shorter holding time followed by annealing steps at lower temperatures with a longer holding time. This improvement can be attributed to 1:2 cation ordering within the crystal, which is taking place during annealing process. The Ba(Co 0.7 Zn 0.3 ) 1/3 Nb 2/3 O 3 ceramic could be used successfully for realization of dielectric microwave resonators, since it has a high quality factor Q f value of 123,700 GHz, a high dielectric constant ε r value of 34.5 and a temperature coefficient of the resonant frequency τ f of 0 ppm/ ¥ C.

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Section: Microwave Dielectric Propertiessupporting

confidence: 90%

Section: Microwave Dielectric Propertiesmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Effect of Post-Annealing on the Microstructure and Microwave Dielectric Properties of Ba(Co0.7Zn0.3)1/3Nb2/3O3 Ceramics

Itaalit¹,

Mouyane²,

Bernard³

et al. 2015

Applied Sciences

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“…The s f values in our work also increased with increasing doping content. According to published literature [5,27], we can rational assume that the s f value of BCZN phase is nearly 0 ppm/°C. When the doping amount increased from 0 to 0.06, the SEM (EDS) results above indicated that the increase of s f value can be owing to the relatively increasing amount of secondary phase Ba 8 CoNb 6 O 24 , reportedly having a positive s f value of nearly 14 ppm/°C [32], which can reasonably explain the rising trend of the s f value with increasing Y 2 O 3 doping in the Ba(Co 0.6 Zn 0.38 ) 1/3 Nb 2/3 O 3 solid solution.…”

Section: Resultsmentioning

confidence: 98%

“…Azough et al [27] reported that perfect properties of 0.7BZN-0.3BCN (e r = 34.5, Q 9 f = 97000 GHz, s f * 0) ceramics have been developed under slowly annealing condition of 60°C/h with 0.4 wt% CeO 2 addition. Ba(Ga 1/ 2Ta 1/2 )O 3 -doped BZN ceramics have been prepared by the mixed oxide route, achieving good microwave dielectric characteristics of e r = 37 and Q 9 f = 90,469 GHz [28], but the s f value was not clear.…”

Section: Introductionmentioning

confidence: 99%

Effects of Y2O3 substitution on microwave dielectric properties of Ba(Co0.6Zn0.38)1/3Nb2/3O3 ceramics

Zhou

Zhang

Yang

et al. 2015

J Mater Sci: Mater Electron

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The effects of Y 2 O 3 substitution on the microstructure and microwave dielectric properties of Ba(Co 0.6-x Y x Zn 0.38 ) 1/3 Nb 2/3 O 3 (x = 0-0.06) ceramics prepared by the conventional solid-state route technique were investigated. The X-ray diffraction results presented that all the well sintered samples exhibited the main phase BaZn 0.33 Nb 0.67 O 3 -Ba 3 CoNb 2 O 9 and a certain amount of Ba 8 CoNb 6 O 24 second phase. The 1:2 B-site cation ordering degree was found to influenced by the replacement of Y 3? , especially for x = 0.02. Then the scanning electron microscopy pictures of the optimally well-sintered (1375°C for 20 h) ceramics has shown a dense microstructure. Although the e r almost kept unchanged, appropriate doping content would greatly improve the Q 9 f value. Meanwhile, the s f value increased slightly with increasing x. At last, the excellent microwave dielectric properties of e r = 35.21, Q 9 f = 72,046 GHz, s f = 3.65 ppm/°C were obtained for x = 0.02 sintered in air at 1375°C for 20 h.

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List of Low‐Loss Ceramic Dielectric Materials and Their Properties

2017

Microwave Materials and Applications 2V Set

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AbbreviationsST = sintering temperature ( • C) r = relative permittivity , f = measurement frequency (GHz) f = coefficient of temperature variation of resonant frequency (ppm/ • C) No. = serial number Qf = quality factor frequency product (GHz)The table lists the key property data of microwave dielectric materials available from published materials. These data are the relative permittivity ( r ), the product of the Q-factor and the frequency (Qf ), the frequency of measurement (f), and the temperature coefficient of the resonant frequency ( f ). In tabulating these data, we make no judgment on the measurement method and the reliability of the result. It is known that the ceramic properties such as porosity, grain size, raw materials used, impurities, measurement methods, and equipment used for measurements affect the dielectric properties and readers should be aware that exact comparison of data on materials of identical composition and manufactured in different laboratories using different processing conditions and measured by different methods would be expected to lead to small variations in properties. The data of dielectric measurements carried out using impedance methods at low (MHz) frequency is excluded as the errors in these methods mean that a loss tangent less than 10 −3 is unreliable. The data are arranged in the order of increasing relative permittivity. The quality factor of the microwave dielectric ceramics decrease significantly with increasing relative permittivity, as shown in Figure A.1. The inset in the figure shows the variation of quality factor frequency product with Microwave Materials and Applications, First Edition. Edited by Mailadil T. Sebastian, Rick Ubic and Heli Jantunen.

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Effect of CeO2 on the sintering behaviour, cation order and properties of Ba3Co0.7Zn0.3Nb2O9 ceramics

Cited by 37 publications

References 13 publications

Effect of Post-Annealing on the Microstructure and Microwave Dielectric Properties of Ba(Co0.7Zn0.3)1/3Nb2/3O3 Ceramics

Effect of Post-Annealing on the Microstructure and Microwave Dielectric Properties of Ba(Co0.7Zn0.3)1/3Nb2/3O3 Ceramics

Effects of Y2O3 substitution on microwave dielectric properties of Ba(Co0.6Zn0.38)1/3Nb2/3O3 ceramics

List of Low‐Loss Ceramic Dielectric Materials and Their Properties

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