Modification of ZnAl2O4-Based Low-Permittivity Microwave Dielectric Ceramics by Adding 2MO–TiO2 (M=Co, Mg, and Mn)
Abstract:ZnAl2O4-based microwave dielectric ceramics with added 2MO–TiO2 (M=Co, Mg, and Mn) were synthesized using the solid-state reaction. The effects of 2MO–TiO2 additions on the microstructures, phase compositions, and microwave dielectric properties of the 0.79ZnAl2O4–0.21M2TiO4 ceramics has been investigated. It can be observed from X-ray diffraction results that the single-phase solid solution in the 0.79ZnAl2O4–0.21Co2TiO4 ceramics, and second-phase rutile, MgTi2O5, and ZnMn3O7 in the 0.79ZnAl2O4–0.21TiO2, 0.79ZnAl2O4–0.21Mg2TiO4, and 0.79ZnAl2O4–0.21Mn2TiO4 ceramics, respectively, appear. The r and f values of the 0.79ZnAl2O4–0.21M2TiO4 ceramics are weakly dependent on the M element (Co, Mg, and Mn). The r values of the 0.79ZnAl2O4–0.21M2TiO4 ceramics (about 9.7) are lower than that of the 0.79ZnAl2O4–0.21TiO2 ceramics (r=11.6), whereas the f values of the former (about −65 ppm/°C) are higher than those of the latter (f=−0.4 ppm/°C). However, in contrast to the Q×f value of the 0.79ZnAl2O4–0.21TiO2 ceramics (Q×f=74 000 GHz), the magnitude of the 0.79ZnAl2O4–0.21Co2TiO4 ceramics increases to 94 000 GHz and that of the 0.79ZnAl2O4–0.21Mg2TiO4 ceramics improves more than twice, whereas the value of the 0.79ZnAl2O4–0.21Mn2TiO4 ceramics undergoes a sharp decline and reaches a minimum of 23 530 GHz at about 6.5 GHz.
Document Type: Research Article
Affiliations: Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
Publication date: 2008-06-01