JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2016
·Vol. 28
·期 2
·1597-1604
·
IF 1.798
Yang Z. L.,Pan H. L.,Jiang X. S.,Wu H. T.
Low loss microwave dielectric ceramics Zn 0.92 Co 0.08 ZrNb 2 O 8 with wolframite structure were prepared by the solid state method. Sintering characteristics, phase composition and microwave dielectric properties were investigated systematically. X-ray diffraction results showed that all samples exhibited a wolframite structure. Rietveld refinement was used to analyze the crystal structure. Based on the lattice parameters, the bond ionicity, the lattice energy, the bond energy and the coefficient of thermal expansion were calculated to evaluate the structural characteristics. The ε
r
values could be strongly dependent on the bond ionicity of the Nb–O bonds. The Q·j values were main affected by the lattice energy and the bond energy of the Nb–O bonds. As for the τ
f
values, it could be mainly affected by the coefficient of thermal expansion of Zn/Co–O bonds. At the sintering temperature of 1200 °C, Zn 0.92 Co 0.08 ZrNb 2 O 8 ceramics exhibited the excellent microwave properties of ε
r
= 27.10, Q·f = 61,036 GHz (at 8.54 GHz) and τ
f
= −9.81 ppm/°C. These results demonstrated that Zn 0.92 Co 0.08 ZrNb 2 O 8 ceramics could be promising candidate materials for the application of highly selective microwave ceramic resonators and filters.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2017
·
IF 3.133
J.X. Bi,C.F. Xing,Y.H. Zhang,C.H. Yang,H.T. Wu
Wolframite-structured Zn 1−x Ni x ZrNb 2 O 8 (0 ≤ x ≤ 0.1) ceramics were synthesized by the conventional solid-state method. The effects of Ni 2+ substitution on sintering characteristic, crystal structure, and microwave dielectric properties of ZnZrNb 2 O 8 samples were systematically studied. The relationship among bond ionicity, lattice energy, thermal expansion coefficient and microwave dielectric properties was also investigated by the complex chemical bond theory. The dielectric constant of Zn 1−x Ni x ZrNb 2 O 8 ceramics sintered at 1150 °C slightly decreases from 28.06 to 26.35 with the increasing Ni 2+ content, which can be explained by the variation of bond ionicity and polarizability. Raman scattering spectra also reveal that the increase in Ni 2+ content leads to the shift in all the vibration modes and the variation of ionicity in Nb O bond. The Q · f values increases from about 40,000 to 60,000 GHz with the increasing Ni 2+ content, which can be explained by the variation of lattice energy. As for τ f value, it is shifted to positive direction, which can be explained in term of the variation in Nb-site bond energy. In addition, the thermal expansion coefficient plays little effect on the temperature stability of ceramics. Typically, the Zn 0.96 Ni 0.04 ZrNb 2 O 8 samples sintered at 1150 °C exhibit excellent properties with ε r = 27.10, Q · f = 62,700 GHz and τ f = −14.72 ppm/°C.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2018
·Vol. 102
·期 7
·4092-4102
·
IF 2.956
Yunhui Zhang,Haitao Wu
La 2 (Zr 1− x Ti x ) 3 (MoO 4 ) 9 (0 ≤ x ≤ 0.1) ceramics were prepared by the traditional solid-state reaction method. XRD analysis showed that La 2 (Zr 1− x Ti x ) 3 (MoO 4 ) 9 (0 ≤ x ≤ 0.1) ceramics belonged to a trigonal system. Based on the chemical bond theory, the consequences of bond energy, bond ionicity, lattice energy, and thermal expansion coefficient of ceramics on microwave dielectric properties were discussed. As Ti 4+ addition was increased, the reduction in dielectric constant was ascribed to the fact that the polarizability of Ti 4+ is smaller than Zr 4+ , and the downward trend was related to the bond ionicity. Besides, the tendency of Q·f value depended on the packing fraction and the lattice energy. The improvement in τ f value, the increase in bond energy, and the decrease in the coefficient of thermal expansion were all correlated. The far-infrared spectra implied that the absorptions of structural phonon oscillation were the main reason for the maximum polarization contribution. La 2 (Zr 0.92 Ti 0.08 ) 3 (MoO 4 ) 9 ceramics sintered at 750°C for 4 hours exhibited the best dielectric properties ( ε r = 10.33, Q·f = 80 658 GHz, and τ f = 3.48 ppm/°C).
研究领域:
材料科学
·
陶瓷工程
·
电气工程
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Liang Shi,Rui Peng,Huaiwu Zhang,Cheng Liu,Gongwen Gan,Xiaolei Shi,Xueying Wang
CaTi 1-x (Mg 1/2 W 1/2 ) x O 3 (x = 0, 0.02, 0.04, 0.06, 0.08) dielectric ceramics were synthesized via the traditional solid-state reaction method. Crystal structure and microwave dielectric properties of CaTi 1-x (Mg 1/2 W 1/2 ) x O 3 system were systematically investigated based on chemistry bond theory (P–V-L theory) for the first time. The pure perovskite phase was obtained for all doped samples, as confirmed through the XRD and Rietveld refinement results. The lattice characteristics were closely related to the microwave dielectric properties. The bond ionicity, lattice energy, and bond energy affected the dielectric constant, quality factor, and temperature stability of the ceramic material. Through the use of (Mg 1/2 W 1/2 ) 4+ doped on B-site, the CaTi 1-x (Mg 1/2 W 1/2 ) x O 3 system can maintain a high dielectric constant (ε r > 100) while effectively reducing the τ f value from 800 ppm/ ° C to less than 300 ppm/ ° C and improving the Q × f value to 9650 GHz (at 3.76 GHz).
研究领域:
材料科学
·
陶瓷工程
·
微波工程
·
固体化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）