ChemInform Abstract: Dielectric Properties of Ceramics in Ba(Co1/3Nb2/3)O3‐Ba(Zn1/3Nb2/3)O3 Solid Solutions

High Q ceramics of Ba3W2O9 (BW)‐substituted Ba(Zn1/3Nb2/3) O3 (BZN) were prepared with a zero τf through the partial substitution of Zn by Ni and Co. The small concentrations of B‐site vacancies introduced by the substitution of BW accelerated the kinetics and stability of the cation ordering and lowered the sintering temperature. Dense, zero τf, ordered solid solutions such as 0.99Ba(Zn0.3Co0.7)1/3Nb2/3O3–0.01BW with ɛr=34.4 and Q×f=82 000 at ∼8 GHz could be obtained after sintering at 1380°C for 5 h and annealing at 1300°C for 24 h. Partially ordered ceramics in the Zn/Co and Zn/Ni solid solutions show a large gradient in the ordering throughout the pellets, which produces a resonant frequency dependence of their Q×f value. The ordering gradient is associated with the increased constraints on the growth of the 1:2 ordered structure within the interior of larger and thicker pellets and can be minimized by extended annealing.

Section: Resultsmentioning

confidence: 72%

“…3). The changes in Q × f reported in Endo et al 7 . for even longer heat treatments of BW‐free BZN–BCoN are also plotted in Fig.…”

Section: Resultsmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Influence of Non‐Stoichiometry on the Structure and Properties of Ba(Zn_1/3Nb_2/3)O₃ Microwave Dielectrics. IV. Tuning τ_f and the Part Size Dependence of Q×f

Davies

2006

Microstructure and Microwave Dielectric Properties of (1−x)Ca(Mg_1/3Ta_2/3)O₃/xCaTiO₃Ceramics

Liu

Chen

et al. 2008

Dense (1−x)Ca(Mg1/3Ta2/3)O3/xCaTiO3 ceramics (0.1≤x≤0.9) were prepared by a solid‐state reaction process. The crystal structures and microstructures were characterized by X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. Single‐phase solid solutions were obtained in the entire composition range. Long‐range 1:2 ordering of B‐site cations and oxygen octahedra tilting lead to the monoclinic symmetry with space group P21/c for x=0.1. For x above 0.1, the long‐range ordering was destroyed and the crystal structure became the orthorhombic with space group Pbnm. The microwave dielectric properties showed a strong dependence on the composition and microstructure. The dielectric constant and temperature coefficient of resonant frequency increased nonlinearly as the CaTiO3 content increased while the Qf values decreased approximately linearly. Good combination of microwave dielectric properties was obtained at x=0.45, where ɛr=45.1, Qf=34 800 GHz, and τf=17.4 ppm/°C.

Microwave Dielectric Properties of A‐Site Modified Ba(Co_0.7Zn_0.3)_1/3Nb_2/3O₃ by La³⁺

Bian

Dong

Song

2008

The sintering behavior, ordering state, and microwave dielectric properties of Ba1−xLa2x/3(Zn0.3Co0.7)1/3Nb2/3O3 Ceramics (0≤x≤0.06) were investigated in this paper. The X‐ray diffraction (XRD) results show that all samples exhibit a single perovskite phase except for the sample with x≥0.03. The sinterability is slightly improved by La doping. The long range order (LRO) degree on B‐site is greatly increased with the increase of x value up to x=0.015 and then slightly decreased with the further increase of x due to the increasing amount of second phases. The dielectric constant at microwave frequency decreases slightly with the increase of x when x<0.015 and increases slightly with further increasing x for the samples sintered at 1375°C/10 h. The Q×f value increases with x up to x=0.015 and then decreases with further increase of x, which is consistent with the variation trend of LRO degree. The τf value decreases slightly with the increase of x up to 0.006, then increases greatly with the further increase of x. An optimized dielectric properties of ɛr=34, Q×f=63 159, GHz and τf=5.21 ppm/°C were obtained for the x=0.01 sample sintered at 1425°C/10 h.