Effect of nonstoichiometry on the structure and microwave dielectric properties of Ba(Co1/3Nb2/3)O3 ceramics

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

doi:10.1016/j.jeurceramsoc.2006.02.004

Cited by 45 publications

(21 citation statements)

References 19 publications

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“…It can be seen that the surface XRD pattern (Figure 4a) phases are only formed on the surface of the BCZN ceramics and that they represent secondary phases. The origin of these phases is probably due to the volatilization of some Zn and Co elements during the sintering steps [12]. For post-sinter annealed ceramics it can be seen from Figure 5a that analyses show some crystal diffraction peaks at 2θ = 17.72 ¥ (marked by an open circle), which reflects the 1:2 cation ordering within the crystal already observed in previous work [7].…”

Section: Structural Characterizationsupporting

confidence: 65%

“…These results clearly show that the Ba8(Co,Zn)1Nb6O24 phase is only formed on the surface of the BCZN ceramics and that it represents a secondary phase. The appearance of this phase is probably due to the volatilization of some Zn and Co elements during the sintering steps [12]. For annealed ceramics (Figure 3), all diffraction peaks in Figure 3a (on the surface) can be attributed to the Ba(Co0.7Zn0.3)1/3Nb2/3O3 and Ba8(Co,Zn)1Nb6O24 phases.…”

Section: Structural Characterizationmentioning

confidence: 98%

“…It can be seen that the surface XRD pattern (Figure 2a) 1 Nb 6 O 24 phase is only formed on the surface of the BCZN ceramics and that it represents a secondary phase. The appearance of this phase is probably due to the volatilization of some Zn and Co elements during the sintering steps [12]. Figure 3b.…”

Section: Structural Characterizationmentioning

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: Structural Characterizationsupporting

confidence: 65%

Section: Structural Characterizationmentioning

confidence: 98%

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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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“…However, the difficulty of their synthesis: high sintering temperatures (Tsint > 1600 0 C), the necessity of long additional annealing (Tann ≈ 1500 0 C, 20-120 h), low reproducibility of properties, as well as the high price of tantalum (in 2000, the price of reagents containing tantalum increased by 500%) calls for search for new promising systems. Therefore, in recent years, attention has been given just to niobium-containing Ba(Nb2/3B 2+ 1/3)O3 compounds (where B 2+ = Mg, Zn, Co), which crystallize in perovskite structure [118,119,120].…”

Section: Ba(m 2+mentioning

confidence: 99%

Microwave Dielectrics Based on Complex Oxide Systems

Белоус¹

2012

Dielectric Material

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“…Among them, Ba(Zn 1/3 Nb 2/3 )O 3 -Ba(Co 1/3 Nb 2/3 )O 3 (BZN-BCN, BCZN) with high quality factor (Q 9 f) value, adjustable temperature coefficient of resonant frequency (s f ), comparatively cheap price of Nb 2 O 5 , and low sintering temperature is highlighted [1,[4][5][6]. The microwave dielectric properties of BZN is e r = 41.0, s f = 30 ppm/°C [7], whereas that of BCN is e r = 32.0, s f = -12 ppm/°C [8], suggesting that the e r and s f can be varied by changing the composition.Then it is well recognized that the high Q 9 f achieved in these complex perovskites is mainly connected with the 1:2 ordered hexagonal structure [3,4,9,10]. The low loss values are obtained when the samples exhibit high ordered degree [3,11].…”

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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Effect of nonstoichiometry on the structure and microwave dielectric properties of Ba(Co1/3Nb2/3)O3 ceramics

Cited by 45 publications

References 19 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

Microwave Dielectrics Based on Complex Oxide Systems

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

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