Effects of Postdensification Annealing on Microwave Dielectric Properties of Ba([Mg 1− x Co x ] 1/3 Nb 2/3 )O 3 Ceramics

Zhai

2018

SSP

Ba(Co1/3(Nb1-xW5x/6)2/3)O3 (0<x≤0.05) (BCWN) microwave dielectric ceramics have been prepared by solid-state reaction method. The microstructure and microwave dielectric properties of BCWN ceramics were investigated systematically in this paper. The results show that the sintering temperature decreases with the substitution of W6+. The Ba(Co1/3(Nb1-xW5x/6)2/3)O3 solid solution is formed with the small substitution of W6+ (x≤0.01). With the increase of x, the impurity phase BaWO4 occurrs and the grains become less homogeneous. Combined with the analysis of X-Ray Diffraction, the cation ordering degree on B-site increases in the sample of x=0.01, which leads to the decrease of the dielectric loss. However, the second phase BaWO4 inhibits the formation of the ordered structure with the reduction of sinterability. Due to the formation of BaWO4, the values of εr and τf of all samples decrease subsequently. The optimized microwave dielectric properties of Ba(Co1/3(Nb1-xW5x/6)2/3)O3 ceramics were obtained in the samples of x=0.01: εr=33.8, Q×f =110761 GHz, τf = -17 ppm/°C.

Section: Introductionmentioning

confidence: 99%

Structural Evolution and Microwave Dielectric Properties of Ba(Co1/3(Nb1-xW5x/6)2/3)O3 Ceramics

Zhai

2018

SSP

“…Furthermore, the price of Ta 2 O 5 has increased nowadays. The cost and limited resources of Ta have spurred the search for alternative materials like Nb‐analog, such as ZnNb 2 O 6 , Ba(Zn 1/3 Nb 2/3 )O 3 (BZN), Ba(Mg 1/3 Nb 2/3 )O 3 (BMN), and etc .…”

Section: Introductionmentioning

confidence: 99%

“…In many complex perovskites, generally, the cation order–disorder transitions have played an important role in phase stability and, of course, dielectric response . Many strategies have been made to improve the degree of B‐site cation ordering of Ba(B′ 1/3 B″ 2/3 )O 3 , such as controlled sintering/annealing, nonstoichoimetry, substitution of appropriate ions, and etc .. For instance, the ordering parameter increases with slight Mg‐deficiency in BMN, and reaches its maximum as x = 0.02, where the Q × f value was improved to 96 000 GHz . However, although the effect of cation ordering on the improvement of Q in Ba(B′ 1/3 B″ 2/3 )O 3 has long been discussed, the addressed viewpoints still remain conflicting, and high Q × f values could also be obtained in disordered BMT‐based ceramics .…”

Section: Introductionmentioning

confidence: 99%

Microwave Dielectric Properties and Thermally Stimulated Depolarization Currents of (1−x)Ba(Mg_1/3Nb_2/3)O₃–xBaSnO₃ Solid Solutions

et al. 2015

Microwave dielectric ceramics of (1−x)Ba(Mg1/3Nb2/3)O3‐xBaSnO3 [(1−x)BMN‐xBS] with high quality factors was synthesized by the solid‐state reaction method. The effects of BaSnO3 additions (x = 0–0.2) on the sinterability, crystal structures, microwave dielectric properties, and microwave dielectric loss mechanisms of BMN were investigated systematically. The degree of 1:2 cation ordering was decreased with increasing Sn content and eventually faded away as x ≥ 0.1, where the low‐temperature relaxations disappeared coincidently through the thermally stimulated depolarization current technique. It was supposed to be the short‐range misplacements of the B‐site cations within the long‐range ordered structure. Meanwhile, the high‐temperature relaxations associated with the in‐grain oxygen vacancies were found in all the title compounds. Though the concentrations of oxygen vacancies of 0.8BMN‐0.2BS were higher than BMN, high Q × f values could also be obtained even in the absence of 1:2 cation ordering. Specifically, the excellent characteristics like εr = 29.02, Q × f = 90 000 GHz and τf = 6.3 ppm/°C were achieved in the specimens of x = 0.2 sintered at 1450°C.

“…However, the postdensification annealing process is always sluggish, and it is usually not desired in the commercial applications . Tamura et al .…”

Section: Introductionmentioning

confidence: 99%

“…6,7,9 However, the postdensification annealing process is always sluggish, and it is usually not desired in the commercial applications. 13,14 Tamura et al showed that this problem could be overcome through minor additions of BaZrO 3 , typically less than 5 mol%, which obviously reduced the annealing time to less than 10 h. 15 Higher Qf values were obtained with the reduced processing time in both Ba(Zn 1/ 3 Ta 2/3 )O 3 and Ba(Mg 1/3 Nb 2/3 )O 3 systems by introducing small amounts of BaZrO 3 . The high Qf values of these ceramics were attributed to the stabilization of the orderinginduced domain boundaries by partial segregation of Zr.…”

Section: Introductionmentioning

confidence: 99%

Microstructures and Microwave Dielectric Properties of Ba((Co_0.55Zn_0.35Mg_0.1)_1/3Nb_2/3)O₃‐BaZrO₃ Ceramics

Pian

et al. 2014

J. Am. Ceram. Soc.

Self Cite

Microstructures and microwave dielectric properties of (1 -x) Ba((Co 0.55 Zn 0.35 Mg 0.1 ) 1/3 Nb 2/3 )O 3 -xBaZrO 3 (x = 0.01, 0.02, 0.03, 0.04, 0.05, and 0.06) ceramics have been investigated. The 1:2 ordered structure remains in the solid solutions when x is less than 0.03, but the ordering is destabilized. While, the local ordering behavior, which generates from compositional inhomogeneous, is observed in the composition with x = 0.04, where the 1:1 ordered phase begins to form. For x = 0.05 and 0.06, the solid solutions are comprised of nanometer-sized 1:1 and 1:2 ordered domains, those are dispersed in a disordered matrix. The lower Qf values of the as-sintered ceramics mainly because of the lower ordering degrees. BaZrO 3 substitution decreases both the annealing time and temperature. The effects of annealing process upon the improvement of Qf values are significant for the lower substitution levels (x = 0.01 and 0.02), while only slight effects are determined for high substitution levels (x = 0.04, 0.05, and 0.06). The highest Qf value of 84,500 GHz is obtained for 1 mol% BaZrO 3 substituted composition, after annealing at 1300°C for 8 h.